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Atomic Spectrometry

The FIAS-Furnace Technique

User’s Guide

Notice

The information contained in this document is subject to change without notice.

Software programs are protected by copyright. It is unlawful to duplicate these programs in any manner other than for the user’s personal use. Specifically, it is unlawful to use or duplicate these programs other than for use with the purchaser’s original computer.

Release history

Trademarks

Perkin Elmer is a registered trademark of affiliates of Perkin Elmer LLC.AA WinLab, HGA and THGA are trademarks of affiliates of Perkin Elmer LLC.

Registered names, trademarks, etc. used in this document, even when not specifically marked as such, are not to be considered unprotected by law.

Copyright information

This document contains proprietary information that is protected by copyright. All rights are reserved. No part of this document may be reproduced in any form whatsoever or translated into any language without the prior written permission of Perkin Elmer LLC or one of its affiliates.

Copyright ©1993-1999 by affiliates of Perkin Elmer LLC

Printed in the Federal Republic of Germany

Technical DocumentationPerkin Elmer BodenseewerkD-88662 Ueberlingen, Federal Republic of Germany

Certificate No. FM 22178

Perkin Elmer Bodenseewerk is registered for the design andmanufacture of laboratory analytical equipment under the qualityrequirements of BS EN ISO 9001.

Part Number Release Publication Date

0993-5250 12

June 1997August 1999

2-9

Chapter 1 Analyzing Samples using the FIAS-Furnace Technique — SummarySafety precautions for the FIAS-furnace technique . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2

Summary of the setup and analysis procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3

Chapter 2 Setting Up the FIAS-Furnace SystemSummary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2

Switching on the FIAS-furnace system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3

Installing and aligning the quartz pipet tip . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4

Installing the quartz pipet tip and sample transfer tube . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4

Aligning the quartz pipet tip . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5

Pretreating the graphite tube for the FIAS-furnace technique . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6

Setting up the flow-injection system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7

Flow injection technique — for all spectrometers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-7

Continuous flow technique for all spectrometers except the model 4100ZL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-8

Continuous flow technique for the model 4100ZL spectrometer . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Starting and adjusting the FIAS gas and liquid flows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-10

Chapter 3 Creating Methods — All Spectrometers Except Model 4100ZLSummary of creating FIAS-furnace methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2

Information to help you create FIAS-furnace methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3

FIAS program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3

Furnace program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4

Furnace sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5Examples of FIAS and furnace programs for flow-injection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-6Examples of FIAS and furnace programs for continuous flow. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7Examples of FIAS and furnace programs for flow-injection with several injections . . . . . . . . . . . . . 3-8

The FIAS-Furnace TechniqueUser’s Guide Contents

0993-5250 C-1

Contents

. . 5-2

. 5-

. .

Chapter 4 Creating Methods — Model 4100ZLSummary of creating FIAS-furnace methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2

Information to help you create FIAS-furnace methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3

FIAS program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3

Furnace program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4

Furnace sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5Examples of FIAS and furnace programs for flow-injection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-6Examples of FIAS and furnace programs for continuous flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-7Examples of FIAS and furnace programs for flow-injection with several injections . . . . . . . . . . . . . 4-8

Chapter 5 Optimizing the Analytical ConditionsMaking adjustments and measurements — Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Before you start making measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2

Making measurements to check the optimization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2

Adjustments to improve the sensitivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-3

Introduction to the FIAS-furnace technique . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-4

Recommended conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-5

Multi-element conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-6

System components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-7

Sample loops — sample volume . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-7

Reaction coil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-7

Pump tubes, pump speed and pump pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-7

Gas flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-9

Setting up and maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-9

Lamps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-9

Trapping parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-9

Measurement parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-10

Chemical factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-11

Interferences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-11

The importance of testing the samples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-11

Sample solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-11

Oxidation state of the analyte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-11

Foaming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-12

Precipitation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-12

Contamination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-13

Reagents and reference solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-14

Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-15

C-2 0993-5250

Contents

. 6-

Chapter 6 TroubleshootingProblems with the spectrometer, FIAS or other instruments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-2

Problems with the analyses — FIAS-furnace technique . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Chapter 7 Parts ListsParts provided . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-2

Replacement parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-2

Index

Customer Service

0993-5250 C-3

Contents

C-4 0993-5250

Analyzing Samples using the FIAS-Furnace Technique — Summary 1

1Analyzing Samples using the FIAS-Furnace Technique — Summary

Creating Methods4100ZL

Creating Methods

Analyzing SamplesSummary

Setting Up the FIAS-Furnace System

Optimizing Conditions

Troubleshooting

To perform analyses using the FIAS-Furnace technique you need to use a number of instruments. These include the FIAS flow-injection system and a spectrometer that has a graphite furnace atomizer.This chapter gives only a summary of the steps necessary to perform analyses but shows where you will find more detailed descriptions of the necessary procedures.

ContentsSafety precautions for the FIAS-furnace technique . . . . . . . . . . . . . . . 1-2

Summary of the setup and analysis procedure . . . . . . . . . . . . . . . . . . . 1-3

Or

Parts Lists

0993-5250 1-1

Analysing Samples

ation

tion

Safety precautions for the FIAS-furnace technique

Before you start making measurements, and in order to get the best results, you should be familiar with all the instruments in the system and how to operate them. You should also be aware of the safety procedures in force in your laboratory, especially those concerning atomic spectroscopy instruments.

Below is a summary of the main precautions to take in order to perform FIAS-Furnace analyses safely. All the user’s guides contain detailed safety informat the points at which you may require it.

• Read the user’s guides for all the instruments in the system so that you become familiar with the instruments. Especially, read the safety informain the user’s guides for your spectrometer and flow-injection system.

• Make sure that the fume ventilation system for the work area is working correctly.

• The graphite furnace, when it is heated to incandescence, and the source lamps can emit UV radiation which can damage your eyes.Always wear UV absorbing safety glasses when looking at the furnace or lamps.

• If you use Zeeman-effect background correction, observe the warning in the spectrometer user’s guide about the magnetic field around the graphite furnace.

1-2 0993-5250

Analysing Samples

t

Summary of the setup and analysis procedure

1. Read the safety information in the user’s guides for the instruments you will be using.

2. Set up the system.

For more details see Chapter 2, Setting Up the FIAS-Furnace System and the user’s guides for your system. Briefly:

• Switch on the system.

• Install and align the lamps that you require.

• Condition and pretreat the graphite tube.

• Set up the flow injection tubing.

3. Create a method.

For more details see Chapter 3, Creating Methods — All Spectrometers ExcepModel 4100ZL, or Chapter 4, Creating Methods — Model 4100ZL.

4. Prepare the reagents, and the sample, calibration, QC, and check solutions.

5. Create a Sample Information File.

For more details see the online help.

6. Allow the lamps to warm up for at least 10 minutes.

7. Optimize the signal.

For more details see Chapter 5, Optimizing the Analytical Conditions.

8. Load the solutions into the FIAS autosampler tray.

9. Start the analysis.

With AA WinLab you use the Automated Analysis window or the Manual Analysis window to start and control the analyses. For more details see the online help and the user’s guides for your spectrometer.

10. When you have finished the analysis, rinse the flow-injection system thoroughly and shut down the system.

For more details see the user’s guides for the flow-injection system and thefurnace.

0993-5250 1-3

Analysing Samples

1-4 0993-5250

7

-8

9

0

Setting Up the FIAS-Furnace System 22Setting Up the FIAS-Furnace System


Creating Methods




Troubleshooting

ContentsSummary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2

Switching on the FIAS-furnace system . . . . . . . . . . . . . . . . . . . . . . . . 2-3

Installing and aligning the quartz pipet tip . . . . . . . . . . . . . . . . . . . . . 2-4

Installing the quartz pipet tip and sample transfer tube . . . . . . . . . . 2-4

Aligning the quartz pipet tip . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5

Pretreating the graphite tube for the FIAS-furnace technique . . . . . . . 2-6

Setting up the flow-injection system . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7

Flow injection technique — for all spectrometers . . . . . . . . . . . . . 2-

Continuous flow technique for all spectrometers except the model 4100ZL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Continuous flow technique for the model 4100ZL spectrometer . . 2-

Starting and adjusting the FIAS gas and liquid flows . . . . . . . . . . . . .2-1

Or

Parts Lists

0993-5250 2-1

Setting Up

s

as

Summary

1. Read the safety information in your spectrometer and FIAS user’s guidebefore starting FIAS-Furnace analyses.

2. Switch on the system as described on page 2-3.

3. Set up the spectrometer and install and align the lamps that you requiredescribed in the spectrometer user’s guide.

4. Install and align the FIAS-Furnace quartz pipet tip as described on page 2-4.

The quartz pipet tip replaces the normal furnace autosampler pipet tip.

5. Condition and pretreat the graphite tube for FIAS-Furnace analyses as described on page 2-6.

6. Make sure that the FIAS tubing is correctly installed; starting on page 2-7 are examples of configurations for flow injection and continuous flow.

7. Start and adjust the gas and liquid flows as described on page 2-10.

2-2 0993-5250

Setting Up

s

e the

uide

ure sure ion.

guide

ins

Switching on the FIAS-furnace system

1. Read the safety information in your spectrometer and FIAS user’s guidebefore starting FIAS-Furnace analyses.

2. Switch on the fume ventilation system for the work area.

3. Make sure that the spectrometer is correctly installed and connected. Sespectrometer user’s guide for more information.

With some spectrometers, before you switch them on, you must make sure that there is a hollow cathode lamp installed and connected. See the user’s gfor the spectrometer for more information.

4. Turn on the furnace gas supply and adjust the pressure to the value quoted in the spectrometer user’s guide.

5. If you are using the recirculating cooling system for the furnace, make sthat the water level in the cooling system is at the maximum mark. Make that the switch on the rear panel of the cooling system is in the ON posit— or —

Turn on the cooling water supply and set the flow to the value quoted in the spectrometer user’s guide.

6. Make sure that the FIAS pump module and the FIAS autosampler (e.g. AS-90) are correctly connected to the spectrometer. See the FIAS user’s for more information.

For the FIAS-Furnace technique, do not connect the Read-cable between the spectrometer and the FIAS pump module.

You do not require the quartz tube furnace or the FIAS quartz tube.

7. Turn on the FIAS carrier gas supply and adjust the pressure to the valuequoted in the FIAS user’s guide.

8. Switch on the computer.

9. Switch on the FIAS pump module.

10. Switch on the spectrometer.

11. On the computer, start AA WinLab.

12. In AA WinLab, select the FIAS-Furnace technique. The online help contadetailed procedures for using AA WinLab.

0993-5250 2-3

Setting Up

ke pler

m as

Installing and aligning the quartz pipet tip

Installing the quartz pipet tip and sample transfer tube

The sample transfer tube for the FIAS-Furnace technique consists of a quartz pipet tip attached to a metal mount which in turn is attached to a PTFE tube.

1. In the Furnace Control window, click on Align Tip, then click on Unlocked above Rinse or Unlocked. The sampler arm rises out of the rinsing port.

2. Unclip the furnace autosampler sampling tube from the sampler arm and pull the mount of the pipet tip out of the clip on the end of the sampler arm.

3. Secure the furnace autosampler sampling tube and pipet tip to the furnace autosampler so that they cannot be damaged or interfere with the movement of the autosampler arm.

4. Carefully, push the mount of the FIAS-furnace sample transfer tube into the clip on the end of the sampler arm.

5. Clip the sample transfer tube to the sampler arm.

6. Disconnect the rinse-feed tube from the inlet of the rinse pump.

7. With newer autosamplers, click on Unlocked above Rinse, then on Unlocked above Tube to make sure that the sample transfer tube moves freely when the autosampler arm moves.

— or —

With older series autosamplers, rotate the manual control wheel and masure that the FIAS sample transfer tube moves freely when the autosamarm moves.

8. Attach the other end of the sample transfer tube to the FIAS tubing systeshown below.

Sample transfer tube

B050-9612for FIAS-Furnace

Quartz pipet tip

ClipMount

2-4 0993-5250

Setting Up

rm.

ort

mpler

u

tely

r the

Aligning the quartz pipet tip

You must align the arm of the autosampler to ensure that the quartz pipet tip enters the sample injection hole of the graphite tube and dispenses the sample correctly. The pipet tip must not strike the edges of the hole or the L’vov platfo

You must also adjust the arm so that the pipet tip cannot enter the rinsing pwhere it would become contaminated with rinsing fluid.

The procedure is the same as that described for aligning the furnace autosain the spectrometer user’s guide.Since no liquid is dispensed into the graphite tube by the quartz pipet tip, yocannot check the alignment by observing the droplet delivery.

1. Align the autosampler arm horizontally exactly as described in the spectrometer user’s guide.

2. Adjust the depth in the tube so that the quartz pipet tip stops approxima1.5 mm above the L’vov platform. Use the procedure described in the spectrometer user’s guide.

As a guide to distance, the quartz pipet tip has an outer diameter of approximately 1.3mm.

3. Adjust the depth in the rinse port so that the quartz pipet tip cannot enterinse port when the arm moves away from the furnace.

W3.3

Warning: UV Radiation - Risk of Eye DamageThe lamps may emit UV radiation which can damage your eyes. • Always wear UV-absorbing safety glasses when aligning the

autosampler.

0993-5250 2-5

Setting Up

d

ter

.

Pretreating the graphite tube for the FIAS-furnace technique

Before you use a graphite tube for hydride determinations you must treat it with a suitable chemical modifier — iridium chloride. One such pretreatment is usually sufficient for the lifetime of the tube if the clean-out temperature useduring analyses does not exceed 2300°C.

Note: You require the 1000 mg/L (0.1%) solution of iridium chloride (IrCl3) in 10% v/v HCl provided with the FIAS-furnace kit. Further supplies are available from Perkin Elmer.

If the quartz pipet tip is already installed in the furnace autosampler, pipet the modifier solution manually into the graphite tube. You can also set up the furnace autosampler for the normal furnace technique to pipet the modifier automatically, but you must then exchange the furnace sample tube for the FIAS-Furnace sample transfer tube.

1. Install and condition a new graphite tube as described in the spectromeuser’s guide.

2. Set up the furnace program shown below.

3. Manually pipet 40 µL of the iridium chloride solution into the graphite tubeMake sure you do not touch the platform inside the tube.

4. In the Furnace Control window, click on Furnace On/Off to start the furnace program.

5. Repeat steps 3 and 4 two more times.

Step Temp Ramp Hold Flow Gas Read

1 110 1 50 250 N

2 130 30 50 250 N

3 1200 20 30 250 N

4 2000 1 5 0 N R

Use fume extraction unit - No.

2-6 0993-5250

Setting Up

Setting up the flow-injection system

• Both flow injection and continuous flow arrangements are possible.

• Install solvent resistant pump tubes if you are using organic solvents.

Flow injection technique — for all spectrometers

The flow system configuration is very similar to that for the FIAS-MHS technique described in the FIAS user’s guide.

3� 3�

Black-white

Reductant

Waste

CarrierSample loop

Red-red

Manifold blocks

Gas/liquid separator

gas Carrier

Sample transfer tubeto furnace autosampler

Waste

Blue-yellow Samplesolution

Reaction coil

0993-5250 2-7

Setting Up

Continuous flow technique for all spectrometers except the model 4100ZL

A suggested flow system configuration for the continuous flow technique is shown below.

3� 3�

Waste

Samplesolution

Reaction coil

Black-white

Red-red

Carriergas

Sample transfer tube

Blue-yellow

Manifold blocks


Reductant

to furnace autosampler

2-8 0993-5250

Setting Up

Continuous flow technique for the model 4100ZL spectrometer

With AAWinlab, the control and coordination of the FIAS system and the graphite furnace has been completely changed compared to PEAALABS. The configuration of the FIAS tubing system is significantly different to that used with PEAALABS.

3� 3�

Waste

Samplesolution

Reaction coil

Black-white

Red-red

Carriergas

Blue-yellow

Manifold blocks


Reductant

Sample transfer tubeto furnace autosampler

Waste

0993-5250 2-9

Setting Up

AA

low

gas

alues

bles.

e

Starting and adjusting the FIAS gas and liquid flows

Detailed descriptions of the procedures to use to set up the FIAS fluid system are given in the FIAS user’s guides. The Recommended Conditions window in WinLab contains recommended values for flow system settings.

Note: Turn on and adjust the carrier gas flow before starting the pumps to prevent liquid entering the non-return valve. If liquid does get into the non-return valve, you must clean it as described in the FIAS Maintenance guide.

1. Set the carrier gas flow to approximately 120 mL/minute using the gas fcontrol knob and the flow meter on the FIAS pump module.

2. If there is no gas flow, the automatic shutdown may be active. To start theflow, in the FIAS Control window, click on Valve Fill/Inject.

3. Start the carrier and reductant liquid flows. Set the pump speeds to the vrecommended in Recommended Conditions window in AA WinLab.

4. Make sure that there are no leaks and that the flow is smooth without bub

5. Set a carrier flow of approximately 6 mL/minute and a reductant flow of approximately 3 mL/minute.

These flow values are different to those recommended for the normal FIAS-MHS technique.

6. Adjust the waste outflow from the gas/liquid separator. Make sure that thmembrane in the gas/liquid separator is clean and dry.

7. Make measurements and optimize the conditions as described in Chapter 5, Optimizing the Analytical Conditions.

2-10 0993-5250

Creating Methods — All Spectrometers Except Model 4100ZL 3

3Creating Methods — All Spectrometers Except Model 4100ZL


Creating Methods




Troubleshooting

ContentsSummary of creating FIAS-furnace methods . . . . . . . . . . . . . . . . . . . 3-2

Information to help you create FIAS-furnace methods . . . . . . . . . . . . 3-3

FIAS program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3

Furnace program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4

Furnace sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5Examples of FIAS and furnace programs for flow-injection . . . . . . 3-6Examples of FIAS and furnace programs for continuous flow . . . . 3-7Examples of FIAS and furnace programs for flow-injection with several injections . . . . . . . . . . . . . . . . . . . . . . . 3-8

Or

Parts Lists

0993-5250 3-1

Creating Methods - except 4100ZL

Summary of creating FIAS-furnace methods

This chapter gives some examples of the FIAS and Furnace programs for the FIAS-Furnace technique and a summary of the procedure to use to create a method. The procedure for creating methods is described in detail in the online help.

In AAWinLab, methods contain parameters and related information that the spectrometer needs to perform analyses and report the results of the analyses. You must use a method to perform an analysis.

You use the Method Editor in AAWinLab to create a new customized method or modify a stored customized method.

Summary of the procedure

1. Create a new method:In the File menu, click on New > Method and select the elements that you are interested in.The software puts the recommended parameter values for the elements that you have selected into the Method Editor.

or

Open a stored, customized method:In the File menu, click on Open > Method and select the method to open.

2. In the Method Editor, select parameter values that are suitable for the analysis you will be doing.

3. Check, then save the method that you have just produced.

3-2 0993-5250


Information to help you create FIAS-furnace methods

This section contains some suggestions and examples of programs for the FIAS-Furnace technique as used with a THGA furnace.

FIAS program

1. On the FIAS page, click on Default to enter the recommended FIAS program for a 500µL sample volume.

2. For Sample Volume, enter the volume of the sample loop you will use.

3. If necessary, change or select the values so that they are suitable for the selected sample volume and the analysis you will be doing.

Notes

• You must always use a prefill step and at least three main steps so that the FIAS and furnace programs will be correctly coordinated.

• The Read buttons on the FIAS page are not active. You set the read command on the Furnace page.

• The time you select for steps 1 and 3 depends on the volume of the sample loop.

• For sample volumes greater than 2mL we recommended that you use a continuous flow setup rather than flow-injection.

0993-5250 3-3


duce

Furnace program

• Click on Default to enter the recommended furnace program for the selected element and a 500µL sample volume. If necessary, change or select the values so that they are suitable for the analysis you will be doing.

• The Hold Time for furnace step 1 must be at least 10 seconds longer than the combined time of FIAS steps 2 and 3. This allows time for the pipet tip to move into the tube and then out of the tube before step 2 of the furnace program starts.

• Do not use a clean-out temperature greater than 2300°C since this will rethe effectiveness and lifetime of the iridium pretreatment.

3-4 0993-5250


Furnace sequence

You use the furnace sequence to coordinate the FIAS and Furnace programs. One of the most important functions of the sequence is to make sure that the sample is transferred from the flow-injection system to the furnace at the correct time. This ensures that the hydride can be trapped efficiently in the graphite tube.

The examples of furnace sequences given later in this chapter produce an analysis that proceeds as shown below.

0

10

20

30

40

50

60

70

80

90

100

Prefill

Step 1

Step 2

Step 3

AutosamplerFurnace program

FIAS program

Time(s)

Step 1

Step 2

Step 3Step 4

Pipet moves into the tube

Pipet moves out of the tube

Trapping stage

0993-5250 3-5


Examples of FIAS and furnace programs for flow-injection

FIAS program

Sample Volume (µL): 500

StepTime(s)

Pump1Speed

Pump 2Speed

Valve

Pre-fill

15 100 0 Fill FIAS autosampler sampling tube rinsed with sample solution - only done for the first replicate.

1 10(15)

100 0 Fill FIAS sample loop fills.15 s are required for a 1000 µL sample loop.

2 5 100 80 Fill FIAS sample loop fills and carrier flow stabilizes.

3 30(50)

0 80 Inject The contents of the sample loop are injected into the carrier stream. The reaction takes place and the hydrides flow into the graphite tube and are trapped.50 s are required for a 1000 µL sample loop.

Furnace program for THGA furnaces

Step TempRamp Time

Hold Time

FlowGas Type

Read Comments

1 250 1 50

(70)

0 N Trapping. Zero gas flow prevents hydrides escaping from the tube.70 s are required for a 1000 µL sample.

2 250 1 20 250 N Drying. Maximum gas flow removes solvent and hydrogen.

3 2000 0 5 0 N Read Atomization and measurement.

4 2300 1 3 250 N Clean-out.

Furnace sequence - coordinates FIAS and furnace programs

Step Actions and Parameters Comments

A Run FIAS steps 1 to 1

B Run Furnace step 1 with FIAS step 2 The furnace is preheated while the sample loop fills and the carrier flow stabilizes.

C Move AS arm into furnace for FIAS steps 3 to 3

The pipet moves into the graphite tube, then FIAS step 3 starts and the hydrides flow into the graphite tube and are trapped.

D Move AS arm out of furnace

E Stop FIAS pumps Saves reagents.

F Run furnace steps 2 to 4 Drying, atomization, measurement and clean-out.

3-6 0993-5250


Examples of FIAS and furnace programs for continuous flow

FIAS program

Sample Volume (µL):

StepTime(s)

Pump1Speed

Pump 2Speed

Valve

Pre-fill


1 5 80 80 Fill The sample is injected into the carrier stream. The reaction takes place and the hydrides flow into the graphite tube and are trapped.Three steps are needed to correctly coordinate the furnace program with the FIAS program.

2 5 80 80 Fill3 60 80 80 Fill


Step TempRamp Time

Hold Time

FlowGas Type

Read Comments

1 250 1 80 0 N Trapping. Zero gas flow prevents hydrides escaping from the tube



4 2300 1 3 250 N Clean-out.




B Run Furnace step 1 with FIAS step 2 The furnace is preheated.




E Stop FIAS pumps Saves reagents.

F Run furnace steps 2 to 4 Drying, atomization, measurement and clean-out.

0993-5250 3-7


Examples of FIAS and furnace programs for flow-injection with several injections

These are similar to the single injection programs, the only difference being that on the Furnace Sequence page, you use the Customize option to add the highlighted step to the furnace sequence.

FIAS program


StepTime(s)

Pump1Speed

Pump 2Speed

Valve

Pre-fill


1 10 100 0 Fill FIAS sample loop fills.

2 5 100 80 Fill FIAS sample loop fills and carrier flow stabilizes.

3 30 0 80 Inject The contents of the sample loop are injected into the carrier stream. The reaction takes place and the hydrides flow into the graphite tube and are trapped..


Step TempRamp Time

Hold Time

FlowGas Type

Read Comments

1 250 1 50 0 N Trapping. Zero gas flow prevents hydrides escaping from the tube.



4 2300 1 3 250 N Clean-out.




B Run Furnace step 1 with FIAS step 2 The furnace is preheated while the sample loop fills and the carrier flow stabilizes.




E Repeat steps A to D Hydride generation and trapping is repeated.

F Stop FIAS pumps Saves reagents.

G Run furnace steps 2 to 4 Drying, atomization, measurement and clean-out.

3-8 0993-5250

Creating Methods — Model 4100ZL 44Creating Methods — Model 4100ZL


Creating Methods




Troubleshooting

ContentsSummary of creating FIAS-furnace methods . . . . . . . . . . . . . . . . . . . 4-2

Information to help you create FIAS-furnace methods . . . . . . . . . . . . 4-3

FIAS program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3

Furnace program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4

Furnace sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5Examples of FIAS and furnace programs for flow-injection . . . . . . 4-6Examples of FIAS and furnace programs for continuous flow . . . . 4-7Examples of FIAS and furnace programs for flow-injection with several injections . . . . . . . . . . . . . . . . . . . . . . . 4-8

Or

Parts Lists

0993-5250 4-1

Creating Methods - 4100ZL

Summary of creating FIAS-furnace methods

In AA WinLab, methods contain parameters and related information that the spectrometer needs to perform analyses and report the results of the analyses. You must use a method to perform an analysis. You use the Method Editor in AA WinLab to create a new customized method or modify a stored customized method.

Summary of the procedure

This a summary of the procedure to use to create a method. The procedure for creating methods is described in detail in the online help.

1. Create a new method:In the File menu, click on New > Method and select the elements that you intend to determine.The system puts the recommended parameter values for the elements that you have selected into the Method Editor.

— or —

Open a stored, customized method:In the File menu, click on Open > Method and select the method to open.

2. In the Method Editor, select parameter values that are suitable for the analysis you will be doing.

3. Check, then save the method that you have just produced.

4-2 0993-5250


ary in

Information to help you create FIAS-furnace methods

This section contains some suggestions and examples of programs for the FIAS-Furnace technique as used with a THGA furnace.

With AA Winlab for the FIAS-Furnace technique, the control and coordination of the FIAS system and the graphite furnace has been completely changed compared to PEAALABS. The default programs and sequences are different and, depending upon the measurement mode required, the configuration of the FIAS tubing system is also different.

This chapter gives specific examples of the FIAS and Furnace programs for the FIAS-Furnace technique with the model 4100ZL spectrometer with AA WinLab, for both flow-injection and continuous flow.

FIAS program

• There are no Pump-0-0-Steps necessary to initiate the movement of the furnace autosampler arm. The coordination of FIAS and the graphite furnace is controlled by the Furnace Sequence Page in the Method Editor.

• AA WinLab contains default programs for the determination of the most common hydride-forming elements using flow injection, with a 500 µL sample loop. These programs do not need to be modified as was necessPEAALABS. On the FIAS page, click on Default to enter the recommended FIAS program for a 500µL sample volume.

• Make sure you enter the volume of the sample loop you will use (Sample Volume).

• You must always use a prefill step and at least four main steps so that the FIAS and furnace programs will be correctly coordinated.

• The Read buttons on the FIAS page are not active. You set the read command on the Furnace page.

• The times you select for FIAS steps 1 and 4 depend on the volume of the sample loop.

• For sample volumes greater than 2 mL we recommended that you use a continuous flow setup rather than flow-injection with single or multiple injections.

0993-5250 4-3


ary in or

duce

Furnace program

• Click on Default to enter the recommended furnace program for the selected element and a 500µL sample volume. If necessary, change or select the values so that they are suitable for the analysis you will be doing.

• AA WinLab contains default programs for the determination of the most common hydride-forming elements using flow injection, with a 500 µL sample loop. These programs do not need to be modified as was necessPEAALABS. Click on Default to enter the recommended furnace program fa 500µL sample volume.

• The Hold Time for furnace step 1 must be at least as long as the combined time of FIAS steps 3 and 4.

• Do not use a clean-out temperature greater than 2300°C since this will rethe effectiveness and lifetime of the iridium pretreatment.

4-4 0993-5250


Furnace sequence

• You use the furnace sequence to coordinate the FIAS and Furnace programs. Unlike the PEAALABS system, there are no Pump-0-0-Steps in the FIAS program necessary to initiate the movement of the furnace autosampler arm.

• One of the most important functions of the sequence is to make sure that the sample is transferred from the flow-injection system to the furnace at the correct time. This ensures that the hydride can be trapped efficiently in the graphite tube.

• The examples of furnace sequences given later in this chapter produce an analysis that proceeds as shown below.

0

10

20

30

40

50

60

70

80

90

100

Prefill

Step 1

Step 2

Step 4

Step 3

AutosamplerFurnace program

FIAS program

Time(s)

Step 1

Step 2

Step 3Step 4

Pipet moves into tube

Pipet moves out of tube

Trapping stage

0993-5250 4-5


Examples of FIAS and furnace programs for flow-injection

FIAS program


StepTime(s)

Pump1Speed

Pump 2Speed

Valve

Prefill 15 100 0 Fill FIAS autosampler sampling tube rinsed with sample solution - only done for the first replicate.

1 2 100 0 Fill FIAS sample loop fills.2 3 100 0 Fill FIAS sample loop fills while pipet moves into the graphite

tube.3 5 100 80 Fill FIAS sample loop fills. The reagents start flowing.4 30 0 80 Inj The contents of the sample loop are injected into the carrier

stream. The reaction takes place and the hydrides flow into the graphite tube and are trapped.30 s are sufficient for a 500 µL sample loop.


Step TempRamp Time

Hold Time

FlowGas Type

Read Comments

1 250 1 50 0 N Trapping. The graphite tube heats up to the trapping temperature. Zero gas flow prevents the hydrides escaping from the tube.


3 2000 0 5 0 N Read Atomization and measurement.4 2300 1 3 250 N Clean-out.

Furnace sequence - coordinates FIAS and furnace programsStep Actions and Parameters Comments

A Run FIAS steps 1 to 1B Move AS arm into furnace for

FIAS steps 2 to 2The pipet moves into the graphite tube while the sample loop fills.

C Run furnace steps 1 with FIAS step 3

The furnace heats up while the sample loop fills.

D Run FIAS steps 4 to 4 The hydrides flow into the graphite tube and are trapped.E Move AS arm out of furnaceF Stop FIAS pumps Saves reagents.G Run furnace steps 2 to 4 Drying, atomization, measurement and clean-out.

4-6 0993-5250


Examples of FIAS and furnace programs for continuous flow

FIAS program

Sample Volume (µL):

StepTime(s)

Pump1Speed

Pump 2Speed

Valve


1 2 80 80 Fill FIAS tubing flushed with sample. Hydrides formed are flushed to waste.

2 2 80 80 Fill FIAS tubing flushed while pipet moves into the graphite tube.3 2 80 80 Fill FIAS tubing flushed while furnace preheats.4 60 80 80 Inject The hydrides flow into the graphite tube and are trapped.


Step TempRamp Time

Hold Time

FlowGas Type

Read Comments






A Run FIAS steps 1 to 1B Move AS arm into furnace for

FIAS steps 2 to 2The pipet moves into the graphite tube while the FIAS tubing fills.


The furnace heats up while the FIAS tubing fills.

D Run FIAS steps 4 to 4 The hydrides flow into the graphite tube and are trapped.E Move AS arm out of furnaceF Stop FIAS pumps Saves reagents.G Run furnace steps 2 to 4 Drying, atomization, measurement and clean-out.

0993-5250 4-7


Examples of FIAS and furnace programs for flow-injection with several injections

These are similar to the single injection programs, but with an extra step in the furnace sequence. On the Furnace Sequence page, use the Customize option to add the highlighted step to the furnace sequence.

FIAS program

Sample Volume (µL): 500Step Time Pump1 Pump 2 Valve


1 2 100 0 Fill FIAS sample loop fills.2 3 100 0 Fill FIAS sample loop fills while pipet moves into the graphite tube.3 5 100 80 Fill FIAS sample loop fills. The reagents start flowing.4 30 0 80 Inj The contents of the sample loop are injected into the carrier

stream. The reaction takes place and the hydrides flow into the graphite tube and are trapped.


Step TempRamp Time

Hold Time

FlowGas Type

Read Comments




Furnace sequence - coordinates FIAS and furnace programsStep Actions and Parameters Comments

A Run FIAS steps 1 to 1B Move AS arm into furnace

for FIAS steps 2 to 2The pipet moves into the graphite tube while the sample loop fills.


The furnace heats up while the sample loop fills.

D Run FIAS steps 4 to 4 The hydrides flow into the graphite tube and are trapped.E Move AS arm out of furnaceF Repeat steps A to E Hydride generation and trapping is repeated.

G Stop FIAS pumps Saves reagents.H Run furnace steps 2 to 4 Drying, atomization, measurement and clean-out.

4-8 0993-5250

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5

Optimizing the Analytical Conditions 55Optimizing the Analytical Conditions


Creating Methods




Troubleshooting

ContentsMaking adjustments and measurements — Summary . . . . . . . . . . . . . 5

Before you start making measurements . . . . . . . . . . . . . . . . . . . . . 5

Making measurements to check the optimization . . . . . . . . . . . . . . 5

Adjustments to improve the sensitivity . . . . . . . . . . . . . . . . . . . . . . 5-

Introduction to the FIAS-furnace technique . . . . . . . . . . . . . . . . . . . . 5-

Recommended conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Multi-element conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-

System components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Sample loops — sample volume . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Reaction coil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Pump tubes, pump speed and pump pressure . . . . . . . . . . . . . . . . .

Gas flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Setting up and maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Lamps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Trapping parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Measurement parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5

Chemical factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-

Interferences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-

The importance of testing the samples . . . . . . . . . . . . . . . . . . . . . .5-

Sample solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-

Oxidation state of the analyte . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-

Foaming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-

Precipitation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-

Contamination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-

Reagents and reference solutions . . . . . . . . . . . . . . . . . . . . . . . . . .5

Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-1

Or

Parts Lists

0993-5250 5-1

Optimizing

Making adjustments and measurements — Summary

Before you start making measurements

• Use the suggestions given in this chapter and in Chapter 2, Setting Up the FIAS-Furnace System to set up the system.

• Use the suggestions given in this chapter and in AA WinLab, in the .Recommended Conditions window, to prepare the samples and reagents. This chapter gives a brief description of the factors that can affect the sensitivity and precision and offers suggestions to enable you to optimize the analytical conditions.

• Use the recommended FIAS and furnace programs as starting conditions. For more information see Chapter 3, Creating Methods — All Spectrometers Except Model 4100ZL and Chapter 4, Creating Methods — Model 4100ZL.

• Make sure that you use correctly prepared reference solutions and blank solutions.

Making measurements to check the optimization

You can make adjustments to the system and observe the effect by watching the signal as it appears on the screen before you make any measurements.

• Make adjustments as suggested below. Change only one parameter at a time and after making an adjustment, wait until the next signal appears before you make a further adjustment.

• When you think that the conditions are optimized, analyze a reference solution and a blank and calculate the characteristic mass. The procedure is described in the online help or the spectrometer user’s guide.

5-2 0993-5250

Optimizing

Adjustments to improve the sensitivity

This is a very brief list of adjustments that you can make to the instruments to improve the sensitivity. For more information about instrument settings, and information about chemical factors that can influence the sensitivity, refer to the remainder of this chapter.

• Slight adjustments to the carrier and reductant flows may improve the sensitivity.

• Slight adjustments to the gas flow may improve the sensitivity. If the carrier gas flow is too high, the mercury or hydride vapor is dispersed too rapidly. If the flow is too low, not all the mercury or hydride may be transferred and trapped. A flow in the range 100–150mL/minute is suitable for most elements. You may need to set ahigher flow if there is a membrane in the gas/liquid-separator.

• Slightly decreasing the flow of waste from the gas/liquid separator may improve the sensitivity. If the waste flow from the gas/liquid separator is too high, sample vapor may escape through the waste outlet. If the waste flow is too low, the fluid level may rise so high that moisture escapes into the sample transfer tubing leading to the quartz pipet tip. If liquid does get into the sample transfer tube, you must clean and dry the tube.

• The absorbance values for each replicate should be similar.If the absorbance for the first replicate is higher than that for subsequent replicates, lengthen the Fill step in the FIAS program to make sure that the sample loop is correctly filled.If the absorbance of the first replicate is lower, lengthen the Prefill step to make sure that the sampling tube from the autosampler is correctly filled.

0993-5250 5-3

Optimizing

ld-hite

rs of lled

ent the to, ace

into ing

Introduction to the FIAS-furnace technique

The FIAS-furnace technique uses a combination of the flow-injection sample preparation technique and graphite furnace atomization and detection. By coupling flow-injection with graphite furnace detection, mercury and the hydride forming elements can be trapped within the graphite tube prior to atomization, thus providing a combination of the high sensitivity of the graphite furnace with specificity and large sample volumes of the flow-injection technique.

Chemical processes in the hydride-generation technique

The hydride-generation technique involves the reaction of acidified aqueous samples with a reducing agent, such as sodium borohydride. The borohydride/acid reduction generates hydrides according to the following equations:

NaBH4+3H2O+HCl → H3BO3+NaCl+8H•

Em++H• (excess) → EHn+H2 (excess)

where E is the analyte of interest and m may or may not equal n.

The hydrides formed are volatile gases which in the FIAS-Furnace technique are transported into the preheated graphite tube by the argon carrier gas. In the graphite tube the hydride decomposes and the analyte element is trapped on the inner surface of the graphite tube. The analyte is atomized and detected using the conventional graphite furnace technique.

Sensitivity

Although the absolute sensitivity obtained with the flow-injection–mercury-covapor/gaseous hydrides (FI-MHS) technique is much lower than that for grapfurnace technique, the relative sensitivity can be improved by up to two ordemagnitude by combining the two techniques. The relative sensitivity is controby the volume of the sample.

To obtain maximum sensitivity you must ensure that the hydride-forming elem(or mercury) is converted to the hydride (or elemental mercury) efficiently in flow injection system and then that all the hydride or mercury is transferred and trapped in, the graphite tube within the time allowed in the FIAS and furnprograms.

The precision is dependent on the injection of a reproducible sample volumea continuously flowing carrier stream and on the reproducible formation, trappand determination of the analyte element.

5-4 0993-5250

Optimizing

Recommended conditions

AA WinLab contains information about recommended analytical conditions and parameter settings for the hydride-forming elements. To see these, display the Recommended Conditions window. The recommended analytical conditions have been selected to allow all of the common hydride forming elements and mercury to be determined using a single FIAS program. Furnace programs vary for each element with regard to the trapping and atomization temperatures.

Optimization of specific parameters may improve the analytical performance somewhat for individual elements. Such optimization may provide better sensitivity or permit the measurement of different oxidation states. If information on optimized conditions exists for an element, it is shown in the Recommended Conditions window for that element.

0993-5250 5-5

Optimizing

Multi-element conditions

With SIMAA 6000 it is possible to measure several hydride forming elements simultaneously, although the possible element combinations are limited by the chemistry involved for hydride generation. When you select more than one element, the default program for hydride trapping suggests using the lowest trapping temperature of the elements defined. However, higher trapping temperatures may provide better results, depending on the sensitivity needed for the individual elements.

Traditionally, hydride generation has used chemical preparation optimized for each element. The ability to perform simultaneous multi-element hydride trapping requires a different approach. Detailed investigations show that the following groups of elements can be determined simultaneously:

• Group A: As(III), Bi(III) and Sb(III)

• Group B: Bi(III) and Se(IV)

• We recommend the determination of Hg and Te on their own, not in combination with other elements.

• As(V) and Sb(V) can be determined together but with reduced sensitivity.

Conditions for group A

Reducing Solution: Reducing As(V) to As(III) and Sb (VI) to Sb(III) is recommended. Add sufficient L-cysteine solution to produce a final concentration of 1% (m/v) in the calibration and sample solutions. Allow to stand for 30 min at room temperature.

Carrier Solution: 1% (v/v) HCl

Reductant Solution: 0.5% (m/v) NaBH4 in 0.5% (m/v) NaOH

Conditions for group B

Reducing Solution: Reducing Se(VI) to Se(IV) is necessary. Add sufficient concentrated HCl to produce a final concentration of 50% (v/v) in the calibration and sample solutions. Heat at 70°C for 2 hours.

Carrier Solution: 10% (v/v) HCl

Reductant Solution: 0.5% (m/v) NaBH4 in 0.5% (m/v) NaOH

5-6 0993-5250

Optimizing

System components

Sample loops — sample volume

With flow-injection the sensitivity of the analysis depends on the amount of sample used for the determination. The volume of sample used for the analysis is determined by the size of the sample loop, located on the injection valve. A typical analysis uses 500 µL of sample. However, the sensitivity can be altered by decreasing or increasing the size of the sample loop.

Sensitivities listed in the Recommended Conditions window are based on sample volumes of 500 µL. For sample volumes greater than 2 mL we recommended that you use a continuous flow configuration rather than flow-injection.

Reaction coil

The amount of time permitted for the reaction of the sodium borohydride and sample may also affect the sensitivity. The reaction time is determined by the length of the reaction coil. This is the tube that joins the confluence of the reductant and carrier streams to the argon inlet of the manifold. A longer reaction coil results in an increased reaction time. For most elements the recommended 300 mm reaction coil is sufficient.

In some cases it may be advantageous to insert a longer reaction coil. In this way a reduction that requires a longer reaction time can take place within the system. For example, with a long reaction coil, arsenic (V) can often be measured directly, without pre-reduction. However, a reaction coil should not be used indiscriminately. Due to the increased reaction time, interferences may arise. Also, lengthening the tubing increases the analysis time.

Pump tubes, pump speed and pump pressure

The flow of the reagents through the system depends on the size and elasticity of the pump tubes and the speed and pressure of the peristaltic pumps. All of these factors can have an effect on pump performance and sensitivity. Before you start an analysis, always make sure that the pump tubes are in good condition and all the connections are secure.

The flow is governed by the combined effect of the speed of the pump and the pressure of the pump rollers on the tube. Wherever possible use the recommended pump speeds. Very high or very low speeds and very high or very low pressures

0993-5250 5-7

Optimizing

result in erratic flows. High speeds and high pressures will wear out the pump tube quickly. You should apply as little pressure as is necessary to give a smooth flow without bubbles.

Recommended pump tubes

Carrier and reductant pump tubes

The dimensions of the pump tubes for the carrier and reductant are critical for trouble-free operation and to obtain the quoted sensitivities. If you need to replace the tubes, use exactly the same type of tube with the same length, internal and external diameters, and material composition. Also, use the same type and size of connectors.

Sample pump tube

The diameter of the pump tube for the sample need only be large enough to ensure that the sample loop is totally filled with sample solution in the time allowed in the FIAS program.

Waste pump tube

The waste pump tube must be sufficiently large to prevent flooding in the gas/liquid separator. If you use higher reagent flow rates or larger diameter reagent pump tubes, you may need to use two waste pump tubes, for example two violet/violet tubes, to drain the gas/liquid separator sufficiently.

If the waste flow out of the gas/liquid separator is too great, sample vapor may escape through the waste outlet. If the waste flow is too low, the gas/liquid separator will be flooded.

Flooding in the separator may result in moisture collecting in the sample transfer tube. This moisture may interfere with the transport of the hydride to the graphite tube.

ID mm Color code

Pump 1 Sample 1.52 blue-yellow

Pump 2 Carrier 1.52 blue-yellow

Reductant 1.14 red-red

Waste 3.18 black-white

5-8 0993-5250

Optimizing

es for n and

flow-

e tion n 10

ct the ndent

ons

Gas flow

The hydride is transferred to the graphite tube by the argon carrier gas. If the argon flow is too high the hydride vapor is dispersed rapidly and some hydride can be carried out of the graphite tube before it is trapped, resulting in low sensitivity and poor precision.

Low carrier gas flows can also decrease the sensitivity if not all of the hydride is transferred to the graphite tube in the time available. Low carrier gas flows may also decrease the sensitivity for the more unstable elements such as tin which may decompose before they get to the graphite tube. Optimization of the carrier gas flow will ensure maximum sensitivity for each element.

If a membrane is used for the gas/liquid separator, the carrier gas flow may have to be increased to 150–200 mL/min.

Setting up and maintenance

Set up the flow-injection and furnace systems as described in the user’s guidthe system. Make sure that the flow system components are in good conditiothere are no leaks. When you shut down the flow-injection system, rinse it thoroughly with deionized water and then pump the water out. Release the pressure on the pump tubes so that they do not become distorted.

Perform maintenance procedures as described in the user’s guides for the injection system and the spectrometer.

Lamps

You may use both hollow cathode lamps (HCL) and electrodeless discharglamps (EDL) for the FIAS-Furnace technique. EDLs typically provide higherenergy than the corresponding HCLs and can improve sensitivity and deteclimits for some elements, such as As and Se. EDLs typically require betweeand 30 minutes warm-up time for stabilization.

Trapping parameters

When the hydride arrives in the graphite tube, the tube must be at the corretemperature (the trapping temperature) to decompose the hydride and trap analyte element on the surface of the tube. Trapping temperatures are depeon the analyte and must be optimized for each element. Recommended temperatures vary between 100°C and 500°C. The Recommended Conditi

0993-5250 5-9

Optimizing

t a 300 . See

e

l can y e

This he

window in AA WinLab contains the recommended temperatures for each element.

To trap the analyte element efficiently, the graphite tube must be pretreated with a suitable chemical modifier. In this procedure, approximately 100mg of Ir are dispensed into the conditioned graphite tube, dried and heated for 20–30s atemperature of 1200°C to reduce the Ir. This treatment lasts for approximatedeterminations, provided that the tube is never heated to more than 2300°CChapter 2, Setting Up the FIAS-Furnace System, for a detailed description of thepretreatment procedure.

Measurement parameters

All spectrometer settings such as wavelength, slit and data processing for thFIAS-Furnace technique are equivalent to those used for the conventional graphite furnace technique.

Since the flow-injection technique normally requires only 0.5mL or less of sample solution for each determination, the solution in one autosampler viabe used for a number of replicates. However, since the reproducibility is vergood, the number of replicate determinations that are necessary to obtain threquired level of precision is usually small.

FIAS and furnace programs

It is important that the FIAS and furnace programs are correctly coordinated. is especially important for the step in which the hydride is transferred form tflow-injection system to the furnace and trapped in the graphite tube. See Chapter 3, Creating Methods — All Spectrometers Except Model 4100ZL, and Chapter 4, Creating Methods — Model 4100ZL, for a description and examples of FIAS and furnace programs.

5-10 0993-5250

Optimizing

Chemical factors

Interferences

Since the analyte is separated from the sample matrix, analyses using the mercury-cold-vapor/hydride-generation (MHS) techniques are largely free of chemical and matrix effects during the measurement stage. Those interferences which may potentially occur are generally associated with sample preparation or fluid flows through the system.

The importance of testing the samples

Some samples exhibit behavior such as foaming and precipitation that can adversely affect the analytical results. A common problem is excessive foaming or precipitation when samples are mixed with NaBH4. To identify such problems, you should test unknown sample types, before you use them in the flow-injection system, to determine if they produce foams or precipitates when you add the reagents you propose to use. You can perform these preliminary tests working in a laboratory hood using a tall, open beaker.

Sample solutions

In the hydride generation technique, the sample solutions must be acidified. Usually the samples must contain the same type and concentration of acid as you use for the carrier solution in the flow-injection system. The Recommended Conditions contain details about the acids you should use.

Oxidation state of the analyte

The oxidation state of the analyte can affect the sensitivity. In solution, arsenic, selenium, antimony, bismuth and tellurium can all exist in one of two oxidation states. The oxidation state affects the rate at which the metal-hydride is formed and thus the sensitivity. To ensure that all of the analyte exists in the same oxidation state, you should reduce the standards and samples when you determine the elements listed above. The Recommended Conditions in AA WinLab contain details about the correct reduction procedure for each element.

0993-5250 5-11

Optimizing

Foaming

Excessive foam production in the gas/liquid separator can result in liquid entering the sample transfer tube and being transported into the graphite tube. If moisture enters the sample transfer tube, it can interfere with the transport of the hydride to the graphite tube. If moisture enters the sample transfer tube, you must clean and dry the tube. If moisture enters the graphite tube, discard the tube and install a new one.

You can usually prevent excessive foaming by placing 1% of an antifoam agent into the reductant solution. The following antifoaming agents have been successfully used in Perkin Elmer applications laboratories.

Precipitation

All solutions used with the flow-injection system must be free of solid particles since these solutions flow through narrow tubes, connectors and valve ports. In addition, precipitates must not be formed during the course of the reaction. Precipitates may be formed for example, when protein-containing samples come into contact with acids or when samples with a high metal content come into contact with sodium borohydride. If precipitation occurs inside the flow-system, you must disassemble and clean the flow-system. To prevent such occurrences, perform appropriate digestions or separations to remove the offending component from such samples.

Antifoam Emulsion110ADow CorningMidland, MI 48601U.S.A.This is available from Perkin Elmeras part number B050-7226

Silicon antifoaming agentType 7743Fa. E. Merck AG6100 DarmstadtGermany

5-12 0993-5250

Optimizing

Contamination

The detection limits obtainable using the flow-injection-MHS (FI-MHS) technique are very often a function of the degree of contamination in the samples and reagents rather than of instrumental capabilities. Contamination is the main source of error when working at the nanogram levels typical for FI-MHS analyses.

The most important prerequisites for minimizing contamination are:

• Careful operation of the instrument.

• Selection of proper sample preparation techniques.

• Good laboratory cleanliness practices.

• Use only high purity double-distilled or, preferably, deionized water to prepare reagent solutions, standard solutions, sample solutions, and for dilutions.

• Ensure that all materials which come into contact with the water or reagent solutions are made of clean inert plastic. Pure water or solutions can quickly become contaminated by impurities from the container in which they are stored, even if the container is made of PTFE.

• Prepare the reagent solutions from chemicals of the highest purity.

0993-5250 5-13

Optimizing

–

Reagents and reference solutions

The factors which can affect the generation of the hydride and the sensitivity can be as simple as not using freshly prepared reductant. The purity of all reagents used is critical when determining low levels of the hydride forming elements. You must make sure that all reductants, acids and reagents are free from the analyte elements and any elements which may react with the generated hydride.

• Prepare the reductant daily and preserve it with sodium hydroxide.

• You can prepare standard solutions for use with the FI-MHS technique by appropriate dilution of stock solutions. Store all standard solutions in inert plastic containers.

• Stock solutions with a concentration of 100 mg/L or more are usually stable for one year.

• Prepare solutions with a concentration of 1 mg/L or less daily.

• For all solutions with concentrations less than 10 mg/L, check the water used for dilution and any acids or other added reagent for contamination by the analyte element.

• Determine the blank concentration of the analyte element in the reducing agents and all other chemicals required for the analysis before use.

• The stability of Hg standards can be strongly affected by adsorption onto the walls of the storage vessel. Prepare Hg standard solutions in a mixture of 2% (v/v) HNO3 and 2% (v/v) H2SO4, with the addition of 1–2 drops (approx. 3060 mL) of a 5% (w/v) KMnO4 solution to stabilize the standard.

5-14 0993-5250

Optimizing

Bibliography

W.B. Robbins and J.A. Caruso, Anal Chem. 51 889A (1979)

J. Dedina, Progress in Anal Spec. 11, 251 (1988)

B. Welz and M. Melcher, Analyst 108, 213 (1983)

N.E. Parisis and A. Heyndricks, Analyst 111, 281 (1986)

P.N. Vijan and G.R. Wood, At. Absorpt. Newsl. 13. 33 (1974)

P.N. Vijan and G.R. Wood, Talanta 23, 89 (1976)

P.D. Goulden and P. Brooksbank, Anal. Chem. 46, 1431 (1974)

E. Sturgeon, S.N. Willie and S.S. Berman, Anal. Chem. (1985),57, 2311-2314

0993-5250 5-15

Optimizing

5-16 0993-5250

-2

Troubleshooting 66Troubleshooting


Creating Methods




Troubleshooting

ContentsProblems with the spectrometer, FIAS or other instruments . . . . . . . . 6-2

Problems with the analyses — FIAS-furnace technique . . . . . . . . . . . 6

Or

Parts Lists

0993-5250 6-1

Troubleshooting

ser’s

em

Problems with the spectrometer, FIAS or other instruments

If you have problems with the instrumentation, spectrometer, FIAS or autosampler, see the troubleshooting and maintenance information in the uguides supplied with these instruments.

Detailed instructions for adjusting flows and cleaning and replacing fluid systcomponents are given in the FIAS user’s guides.

Problems with the analyses — FIAS-furnace technique

Note: For problems directly related to the furnace technique, see the troubleshooting guide provided with the spectrometer and furnace systems.

Problem Possible causes Check or remedy

Characteristic mass too high.Poor sensitivity

Reagents

Reductant is not fresh. Prepare fresh reductant.Reference or blank solutions are not fresh.

Prepare fresh solutions.

Wrong oxidation state of element

See the recommended conditions in the software and Chapter 5, Optimizing the Analytical Conditions

Graphite tube

The tube is not correctly conditioned or pretreated, or the pretreatment has deteriorated.

Condition and pretreat tube as described in Chapter 2, Setting Up the FIAS-Furnace System.


The waste flow from the gas/liquid separator is too high — sample vapor is escaping with the waste.

Adjust the flow.

6-2 0993-5250

Troubleshooting

d

ve

r-

n

... + poor peaks, fast background

The waste flow from the gas/liquid separator is too low — liquid is entering the sample transfer tube.

Adjust the flow, then clean and dry the sample transfer tube.

Membrane is wet Install a new, dry membrane.Gas/liquid separator is contaminated

Clean the gas/liquid separator with hydrochloric acid.

Fluid flows, leaks, blockages, contamination

Carrier gas flow is not adjusted properly.

Optimize the carrier gas flow. See the recommendeconditions in the software and Chapter 2, Setting Up the FIAS-Furnace System.

Ratio of carrier-to-reductant flows is not 2:1.

Check that the carrier and reductant pump tubes hanot been interchanged.

Adjust the carrier and reductant flows.

Replace any worn pump tubing.Leaks in fluid system. Make sure that all the tube connections are finge

tight. If necessary fit new connections and tubes.The fluid system has been used with a different reductant, for example, tin chloride.

Install new tubes, connectors, manifold and gas/liquid separator.

Use the Alternate Reductant Kit — see the spare parts and accessories brochure.

Contaminated fluid system.

Clean the fluid system or install new components ithe fluid system.

Manifold blocked. Clean the manifold with deionized water in an ultrasonic bath. Rinse the manifold with hydrochloric acid followed by deionized water.

Problem Possible causes Check or remedy

0993-5250 6-3

Troubleshooting

6-4 0993-5250

Parts Lists 77Parts Lists


Creating Methods




Troubleshooting

ContentsEquipment provided . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-2

Replacement parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-2

Or

Parts Lists

0993- 7-1

Parts Lists

96

Parts provided

Replacement parts

Qty Description Part No.

1 The FIAS-Furnace Kitwhich contains the following parts: B314-0255

1 Quartz pipet tip 20 mm B051-0032

1 Sample transfer tube with quartz pipet tip B050-9612

1 This User’s Guide 0993-5250

1 50 mL iridium chloride solution B314-0391

Description Part No.

Quartz pipet tip 20 mm B051-0032

Silicone tube, 1m 10 mm required to attach the quartz pipet tip to the mount. B002-97

50 mL iridium chloride solution B314-0391

7-2 0993-

0993-5250 In-1

Index

In-2 0993-5250

Index

Aanalyses

problems 6-2safety precautions 1-2summary of procedure 1-3

analyte 5-14oxidation state 5-11

autosampleraligning 2-5

Ccarrier gas 5-9

adjusting flow 2-10, 5-3

carrier solutionadjusting flow 2-10pump tube 5-8tube position 2-7, 2-8, 2-9

characteristic mass 5-2problems 6-2

chemical factorsoptimization 5-11

clean-out 3-4, 4-4

conditioning the graphite tube 2-6

contamination 5-13

creating methods 3-2, 4-2

FFIAS

flow systemcontinuous flow 2-8, 2-9flow-injection 2-7

setting up 2-3

FIAS program 5-3, 5-10example

continuous flow 3-7, 4-7flow-injection 3-6, 3-8, 4-

6, 4-8information 3-3, 4-3

FIAS-Furnaceintroduction 5-4

methods 3-2, 4-2

foaming 5-12

furnace program 5-10example



furnace sequenceexample



Ggas flow 5-9

adjusting 2-10

gas/liquid separator 5-9position 2-7, 2-8, 2-9

graphite tubemaximum temperature 2-6pretreating 2-6

Hhydride

reactions 5-4trapping 3-5, 4-5

Iiridium pretreatment 2-6

Llamps 5-9

Mmaintenance 5-9

measurement parameters 5-10

mercurystandards 5-14

methodscreating 3-2, 4-2

modifiertube pretreatment 2-6

multi-element conditions 5-6

Ooptimization

chemical factors 5-11summary of procedure 5-2system components 5-7

oxidation state 5-11

Pparts provided 7-2

pipet tipaligning 2-5installing 2-4

precipitates 5-12

precision 5-4

pretreating the graphite tube 2-6

pump tubes 5-7

Qquartz pipet tip

aligning 2-5installing 2-4

Rreaction coil

optimization 5-7position 2-7, 2-8, 2-9

reagentcontainers 5-13contamination 5-13purity 5-14

recommended conditions 5-2, 5-5

reductant 5-14adjusting flow 2-10pump tube 5-8tube position 2-7, 2-8, 2-9

reference solutions 5-14

0993-5250 In-3

Index

replacement parts 7-2

replicates 5-10

Ssafety information 1-2

sampleacidity 5-11analyte oxidation state 5-11containers 5-13contamination 5-13pump tube 5-8testing 5-11volume 5-7

sample loopoptimization 5-7position 2-7, 2-8, 2-9

sample transfer tubeinstalling 2-4position 2-7, 2-8, 2-9

sensitivityadjustments 5-3magnitude 5-4problems 6-2

sequenceexample


6, 4-8

setting upFIAS 2-3

shipping list 7-2

solution containers 5-13

standard solutions 5-14

switching on 2-3

Ttemperature

clean-out 3-4, 4-4furnace program 3-6, 3-7, 3-

8, 4-6, 4-7, 4-8maximum 2-6preatreatment 5-10

pretreatment 2-6trapping 5-9

trapping 3-5, 4-5, 5-4parameters 5-9temperature 5-9

troubleshooting 6-1

tubescarrier solution 5-8flow system configuration 2-7,

2-8, 2-9pump 5-7reaction coil 5-7reductant 5-8sample 5-8sample loop 5-7waste 5-8

UUV radiation 1-2

Wwaste flow

adjusting 2-10, 5-3

waste pump tube 5-8

ZZeeman furnace 1-2

In-4 0993-5250

.

talog,

.

Company Name and Addresses

Supplies, replacement parts, and accessories

Supplies, replacement parts, and accessories can be ordered directly from Perkin Elmer, using the part numbers quoted in the guides provided with the instrument.

Perkin Elmer’s catalog service offers a full selection of high-quality supplies

To place an order for supplies and many replacement parts, request a free caor ask for information:

– If you are located within the U.S., call toll free 1-800-762-4002, 8 a.m. to 8 p.m. EST. Your order will be shipped promptly, usually within 24 hours

– If you are located outside of the U.S., call your local Perkin Elmer sales or service office.

Customer Service

U.S.A.:Perkin Elmer LLC761 Main AvenueNorwalk, Connecticut 06859-0010U.S.A.Phone: 800-762-4000 or (+1) 203-762-4000Fax: (+1) 203-762-4228

Germany:Perkin ElmerVerkauf und ServiceRengoldshauser Strasse 11D-88662 UeberlingenGermanyPhone: (49-7551) 919-0Fax: (49-7551) 919-149

United Kingdom:Perkin Elmer Ltd.Post Office LaneBeaconsfield, Bucks, HP9 1QAEnglandPhone: (44-1494) 676161Fax: (44-1494) 67-9331 & -9333

Perkin Elmer on the Internet:http://www.perkin-elmer.com/ai

ALL ANALYTICAL INSTRUMENTS AND SYSTEMS MANUFACTURED BY PERKIN ELMER ARE DEVELOPED AND PRODUCED UNDER THE QUALITY REQUIREMENTS OF ISO 9001

Perkin Elmer LLC, 761 Main Ave., Norwalk, CT 06859-0010, U.S.A., Tel.: (203) 762-4000

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