total p, po4,n

Watersheds Laboratory Total P – Total N - Hach DR/4000 Spectrophotometer VU Stormwater Partnership SOP – VUSP -B Rev. No.. 3 Villanova University Rev Date March: 2011 of 24

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Villanova University Villanova Urban Stormwater Partnership

Watersheds Laboratory

Standard Operating Procedure – VUSP – B

Total P-Total Orthophosphate – Total N Hach DR/4000 Spectrophotometer Procedures

Author: _____________________________________________________ Water Resources Laboratory Technician – Sonali Joshi Approved: __________________________________________________ VUSP Director Robert G. Traver


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Distribution Mary Ellen Dukart – Quality Assurance Officer Laboratory Copy, maintained by Quality Assurance Officer Revision Date Responsible Person Description of Change 0 30 May 2007 Mary Ellen Dukart Initial 1 31 Oct. 2007 Mary Ellen Dukart 2 01 Sep 2008 Mary Ellen Dukart Typo 3 28 Mar 2011 Sonali Joshi Change Personnel The following laboratory staff have read and been trained on this Manual. A copy of this page will be maintained in the Laboratory. Training is good for one year. Signature Name / Position Date Trainer

Robert G. Traver Director

Bridget Wadzuk PI

Sonali Joshi Quality Assurance Officer


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TABLE OF CONTENTS

1.0 SCOPE AND APPLICATION ......................................................................... 5

2.0. METHOD SUMMARY .................................................................................... 5

3.0. DEFINITIONS ................................................................................................ 6

4.0 HEALTH AND SAFETY WARNINGS ............................................................. 6

5.0. INTERFERENCES ......................................................................................... 7

5.1 Total Phosphorus Interferences ............................................................................................................ 7

5.2 Total Orthophosphate Interferences ..................................................................................................... 7

5.3 Total Nitrogen Interferences ................................................................................................................ 8

6.0. HANDLING AND PRESERVATION .............................................................. 8

7.0. EQUIPMENT AND SUPPLIES ...................................................................... 9

8.0. QUALITY CONTROL .................................................................................. 10

9.0. PROCEDURES ............................................................................................ 11

9.1 Total Phosphorous Procedures .............................................................................................................11

9.2 Total Orthophosphate Procedures .......................................................................................................14

9.3 Total Nitrogen Procedures ....................................................................................................................15

10.0. DATA ANALYSIS AND CALCULATIONS ................................................ 18

10.1 – TOT P HACH DR/4000 Calibration Check Sheet .........................................................................18

10.2 – TOT ORTHO-P HACH DR/4000 Calibration Check Sheet .........................................................20

10.3 – TOT N HACH DR/4000 Calibration Check Sheet ........................................................................22

11.0. WASTE MANAGEMENT ........................................................................... 24

12.0. REFERENCES .......................................................................................... 24


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1.0 Scope and Application

1.1 The purpose of this standard operating procedure (SOP) is to show the proper set up, procedures, and operation steps for determining Total Nitrogen (N), Total Phosphorus (P), and Totoal Reactive Phosphorus (orthophosphate) in rainwater samples using the HACH DR/4000 Spectrophotometer. This document serves as the basis for maintaining accurate and reproducible results, and defines pertinent validation criteria for accepting/rejecting final data.

1.2 The Total N method generally yields 95-100% recovery on organic nitrogen standards. An alkaline persulfate digestion converts all forms of nitrogen to nitrate. Sodium metabisulfite is added after the digestion to eliminate halogen oxide interferences. Nitrate then reacts with chromotropic acid under strongly acidic conditions to form a yellow complex with an absorbance maximum at 410 nm.

1.3 In the Total P method, orthophosphate reacts with molybdate in an acid medium to produce a Phosphomolybdenum complex. Ascorbic Acid then reduces the complex, giving an intense molybdenum blue color.

1.4 In the Total Reactive Phosphorus method, orthophosphate reacts with molybdate in an acid medium to produce a Phophomolybdate complex, giving an intense molybdenum blue color.

1.5 Spiked and duplicate samples will be employed as a means of validating data within range of the instrument’s detection limits, shown below.

Total N and Total P for water samples

Parameter

Nutrients Test Method Hach Method

Number Detection Limit

(mg/L) ASCE/EPA

Database (mg/L) Phosphorus -

Total PhosVer3 with Acid Persulfate Digestion 8190

0.06 mg/L PO4

3-

0.06 mg/L PO43-

Orthosphosphate-Total PhosVer3 Reaction 8048 0.045 mg/L PO4

3- 0.045 mg/L PO43-

Nitrogen - Total Persulfate Digestion 10071 1.7 mg/L N 2.0 mg/L N

2.0. Method Summary 2.1 Both the Total Nitrogen and Total Phosphorus tests are conducted using the Hach DR/4000 Spectrophotometer. The spectrophotometer is designed to measure the concentration of a sample based on the amount of light absorbed at a specific wavelength. This absorbance can be related to various chemical parameters through the use of experimental procedures. The spectrophotometer’s light source can be set to a wide


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range of wavelengths from the visible to the ultraviolet scale. The machine is programmed to perform over 120 procedures. 2.2 Accurate sample volume measurements are crucial to determine the correct concentration of the sample. TenSette Pipets are used to accurately measure sample volumes. Both models 19700-01 (1 ml max) and 19700-10 (10 ml max) pipets are used according to the volume of sample required in the procedure. For quality assurance purposes the tip is replaced between samples to prevent cross-contamination. 2.3 The DR/4000 uses square glass 1-inch Sample Cells for many of the procedures. The recommended cleaning and handling procedures are strictly followed to prevent interference from the glassware. Contact should be avoided with the clear sides of the cells with fingers. The cells are oriented in the 1-inch Square Cell Adapter inside the Sample Module such that the fill marks are facing the user and the clear sides are facing the lamp. The cells are wiped with a soft cloth to remove any smudges or fingerprints. 2.4 The Total Nitrogen and Total Phosphorus spectrophotometric analyses are performed in manufacturer prepared digestion vials. Care is taken not to touch the glass vials. They are held by the plastic caps. The glass vials are also wiped with a soft cloth prior to analysis in the spectrophotometer. Vials are emptied immediately following the analysis into specified hazardous waste containers. The vials are not reusable and are disposed of as per the product’s Material Safety Data Sheet (MSDS). 2.5 The Total Nitrogen and Total Phosphorous tests require the samples to undergo a digestion period at specific temperatures. The Hach COD Reactor Model 45600 is used to incubate the samples for the required times. The COD Reactor holds up to 25 16x100 mm vials and is capable of sustaining temperatures up to 150 degrees Celsius with an accuracy of ± two degrees Celsius. It also has a space for a thermometer to verify the temperature. The COD Reactor features an adjustable temperature and a timer. The reactor has two modes, 150 degrees Celsius mode and an adjustable temperature mode.

3.0. Definitions NA

4.0 Health and Safety Warnings See Lab Safety Plan. Consult the Material Data Safety Sheets (MSDS) for information specific to the reagents used.


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5.0. Interferences Reference HACH 4000 Manual

5.1 Total Phosphorus Interferences

5.2 Total Orthophosphate Interferences


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5.3 Total Nitrogen Interferences

6.0. Handling and Preservation 6.1 All glassware and plastic ware used for collection, transportation, and laboratory analysis of the samples are acid-washed using the following procedure specified by the Hach DR/4000 Spectrophotometer Handbook. The glassware and plastic ware is first cleaned with a laboratory detergent and rinsed with tap water. Next, the container is rinsed in 1:1 Hydrochloric Acid Solution. The container is then rinsed with deionized water three times and allowed to air dry. 6.2 The samples are analyzed immediately upon collection. However, in the event that the samples cannot be analyzed promptly, a preservation plan is in place, as specified by Standard Methods.

Parameter Container Type Preservation Holding Time

Total Nitrogen Total Phosphorus Plastic or glass

H2SO4 to pH <2, store at 4oC. Warm and neutralize with 5 N

NaOH before analysis 28 days Total Reactive Phosphorus

(Orthophosphate) Plastic or glass Store at or below 4oC 24 hours


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7.0. Equipment and Supplies 7.1 Hach DR/4000 Spectrophotometer 7.2 Hach COD Reactor Model 45600 7.3 TenSette Pipets 7.4 Phosphorus, Total

7.5 Orthophosphate, Total

7.6 Nitrogen, Total


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8.0. Quality Control 8.1 A system of standard solutions, blanks, duplicates, and spikes, or “standard

additions,” is used to check the laboratory techniques for the Hach DR/4000 Spectrophotometer. A blank and a spike are incorporated into each set of samples for each parameter being measured.

8.2 The blanks are samples of demineralized water that are treated in the same manner as the samples to be tested. Spikes are “…used to determine the accuracy and precision of the analysis methods in the sample matrix.” (EPA, 2002) The spikes are created by mixing the sample water with a small known volume of a solution of a known concentration. The spike is also treated in the same manner as the other samples. The resulting concentration should represent a mass balance of the known addition and the sample concentration.

8.3 If 100% recovery is not found, a problem exists. The standard additions should be repeated using demineralized water as the sample to check the reagents, instrument, and technique. If approximately 100% recovery is achieved for each addition, there is likely interference in the sample. If a mass balance is not achieved with the demineralized water, the procedure should be checked to verify that it is being followed properly. The first step in checking the procedure involves performance checks on all of the instruments following the Troubleshooting/Service Checks section in the operating manual. Next, the reagents should be checked. The standard additions should be repeated using new reagents. If the problem still cannot be identified it is likely that the standards are not accurate.

8.4 At least one set of duplicate samples are run for every batch analyzed. In this test, one sampling site is chosen at random in which two separate samples are taken and treated/analyzed separately. Both samples should render readings within 20% of each other to be considered valid. If they do not fall within this range, procedures are examined to be sure that all samples were treated in the same manner.


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9.0. Procedures

9.1 Total Phosphorous Procedures Method 8190 (0.06 to 3.50 mg/L PO4

3-)

1. Turn on the COD Reactor and set to 150° C. 2. On the Spectrophotometer press the soft key under HACH PROGRAM, type in 3036

and hit ENTER. 3. In addition to the samples being tested, prepare the following samples for a calibration

check: a. Blank: Use deionized water from the containers in the cabinet b. Standard: Use a prepared standard of 1 ppm (1 mg/L) c. Spike: Choose one sample at random (Csample) and create a spike by adding 5 mL of

the standard and 20 mL of the sample to a small beaker and stirring it (Cspike). Once the sample (Csample) is analyzed the approximate concentration of the spike can be calculated from the equation (Cstd)(Vstd)+(Csample)(Vsample)=(Cspike)(Vspike) and compared to the value that is read on the spectrophotometer.

d. Duplicate: Choose 1 sample (CDUP) to run twice to see if the values come out to be approximately the same.

4. Label each test tube with the sample name. 5. Using a TenSette Pipet, add 5.0 mL of each sample to the Phosphate Acid Reagent test

tube.

6. Add one Potassium Persulfate Powder Pillow to each test tube.

7. Tightly cap each test tube and vortex until it is mixed.

8. Place the test tubes in the COD Reactor and set the timer for 30 minutes. (Either set the timer on the COD Reactor or press the soft key under START TIMER on the spectrophotometer.)

9. When the timer goes off, immediately remove the test tubes from the reactor and set aside

to cool to room temperature. (They’re hot, use the glove!)

10. When the tubes are cooled, use a Tensette Pipet to add 2 mL of 1.54 N Sodium Hydroxide Standard Solution (found in the Total Phosphorus testing box) to each test tube. As long as the tip doesn’t touch the inside of the test tubes you can use the same tip for all samples. Cap and invert the tube 10 times to mix.

11. With the blank only - Clean the outside of the test tube with a Kim wipe, place in the

spectrophotometer and close the lid.


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a. Press the soft key under ZERO so it displays 0.00 mg/L. Remove the blank from the spectrophotometer.

b. Add one PhosVer 3 powder pillow. Cap and vortex for 10-15 seconds. Note: The powder will not completely dissolve.

c. Press the soft key under START TIMER and a 2 minute waiting period will begin. d. When the timer goes off wipe the test tube down again and place in the

spectrophotometer. e. Press the soft key under OPTIONS, (MORE), BLANK: OFF. The reagent blank

number will appear and press ENTER. f. Press EXIT to return to the main screen. The blank will not be used again.

12. Calibration Check. Wipe the outside of the test tube of the Csample, and place it in the

spectrophotometer. a. Press the soft key under ZERO so it displays the blank correction value. b. Add a PhosVer 3 powder pillow. Cap and vortex for 10-15 seconds. Note: The

powder will not completely dissolve. c. Press the soft key under START TIMER and a 2 minute waiting period will begin. d. When the timer goes off wipe the test tube down again and place in the

spectrophotometer and read the total phosphorus value. e. Record this reading. f. Repeat Step 12a-12e to determine the actual concentration of Cstd. Using the

following concentration, calculate Cspike :

(Cstd)(Vstd)+(Csample)(Vsample)=(Cspike)(Vspike) Where: Cstd = approximately 1 mg/L (Use the concentration of the standard as determined by the HACH spectrophotometer) Vstd = 5 mL Csample = The concentration of the sample chosen to create the spike, in mg/L Vsample = 20 mL Vspike = 25 mL Note: Volumes of the standard/sample may be altered at any given time based on conservation of sample requirements. These changes will be included in the results. 13. Repeat Step 12a-12d to determine the actual Cspike. Record this number as the actual

Cspike. Now, calculate the percent difference using the following equation: % Difference = Cspike (calculated) – Cspike (actual) * 100% Cspike (calculated) 14. In order to proceed, the % difference must fall within the range of ±20%. 15. Repeat 12a-12e for the Duplicate samples. Likewise, these reading should agree by 20%.

16. With the remaining samples (Group according to like blank off values) - Wipe the

test tubes and place each in the spectrophotometer to read the value. a. Press the soft key under ZERO so it displays the blank correction value.


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b. Add a PhosVer 3 powder pillow. Cap and vortex for 10-15 seconds. Note: The powder will not completely dissolve.

c. Press the soft key under START TIMER and a 2 minute waiting period will begin. After each group, you can press NEXT TIMER to restart the 2 minute reaction period.

d. When the timer goes off wipe the test tube down again, place in the spectrophotometer, and record the total phosphorus value.

NOTE: You can read each sample before adding the PhosVer 3 powder pillow and group them by their reading so that you can add the powder pillow and zero them in groups rather than individually.


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9.2 Total Orthophosphate Procedures Method 8048 (.045 to 2.500 mg/L PO4

3-) 1. On the Spectrophotometer press the soft key under HACH PROGRAM, type in

3025 and hit ENTER. 2. In addition to the samples being tested, prepare the following samples:

a. Blank: Use HACH provided Deionized (Demineralized) Water b. Standard: Use a prepared standard of approximately 1 ppm Phosphorus (1

mg/L) c. Duplicate: Choose one sample to run twice to verify that the values come

out to be approximately the same. d. Spike: Spike: Choose one sample (Csample) and create a spike by adding 5mL of

the standard and 20 mL of the sample to a small beaker and stirring it (Cspike). Once the sample (Csample) is analyzed the approximate concentration of the spike can be calculated from the equation (Cstd)(Vstd)+(Csample)(Vsample)=(Cspike)(Vspike) and compared to the value that is read on the spectrophotometer.

3. Use a pipet to add 10 mL of sample to a 20 mL square sample cell. Be sure to

mark each cell by placing a strip of masking tape in front of the cells with the sample IDs on it.

4. Add one PhosVer 3 phosphate Powder Pillow to each sample cell. (Powder

pillows are located in the drawer under the spectrophotometer, if there are no additional PhosVer 3 packets, take them from the Total Phosphorus test box and note on the board that they need to be ordered.)

5. Vortex vigorously. Press the soft key under START TIMER and a 2-minute

reaction time will begin. 6. When the timer beeps, place the sample cell containing the blank into the

spectrophotometer and close the lid. Press the soft key under ZERO and it will display 0.000 mg/L.

7. Place each sample cell in the spectrophotometer and read the resulting

concentration in mg/L. 8. Verify the calibration checks.


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9.3 Total Nitrogen Procedures Method 10071 (1.7 to 25.0 mg/L N)

1. Turn on the COD Reactor and set to ADJ. (approx. 105° C) 2. On the Spectrophotometer press the soft key under HACH PROGRAM, type in 2558

and hit ENTER. 3. In addition to the samples being tested, prepare the following samples for a calibration

check: a. Blank: Use HACH provided Deionized (Demineralized) Water b. Standard: Use HACH provided Nitrate Nitrogen Standard Solution, 10 mg/L as

N. c. Spike: Choose one sample (Csample) and create a spike by adding 5mL of the

standard and 20 mL of the sample to a small beaker and stirring it (Cspike). Once the sample (Csample) is analyzed the approximate concentration of the spike can be calculated from the equation (Cstd)(Vstd)+(Csample)(Vsample)=(Cspike)(Vspike) and compared to the value that is read on the spectrophotometer.

d. Duplicate: Choose one sample (CDUP) to run twice to see if the values come out to be approximately the same.

4. Start with the Total Nitrogen Hydroxide Reagent vials. Label each test tube with the

sample name. Note: Please be sure the vials contain the HYDROXIDE reagent. The Acid reagent will explode in the COD reactor.

5. Add one Total Nitrogen Persulfate Reagent Powder Pillow to each test tube.

6. Using a pipet, add 2.0 mL of each sample to the corresponding test tube. Be sure to

change tips for each new sample.

7. Tightly cap each test tube and vortex vigorously to mix for more than 30 seconds. Note: The persulfate reagent may not dissolve completely. This will not affect accuracy.

8. Place the test tubes in the COD Reactor and set the timer for 30 minutes. (Either set the

timer on the COD Reactor or press the soft key under START TIMER on the spectrophotometer.) Be sure the tubes are tightly capped.

9. When the timer goes off remove the test tubes from the reactor and set aside to cool to

room temperature. (They’re hot, use the glove!) Note: It is important to remove the vials from the COD Reactor after exactly 30 minutes.

10. When the tubes are cooled, add one TN Reagent A powder pillow to each vial. Cap and

vortex vigorously for 15 seconds, or until dissolved. (Reagent A powder pillows are found in the Total Nitrogen Acid Reagent test box.) Press the soft key under START TIMER and a 3-minute reaction time will start.


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11. When the timer beeps, add one TN Reagent B powder pillow to each vial. Cap and vortex for 15 seconds. (Reagent B powder pillows found in the Total Nitrogen Acid Reagent test box.) Note: The reagent will not completely dissolve. The solution should turn yellow. Press the soft key under START TIMER and a 2-minute reaction time will start.

12. Label a set of Total Nitrogen Acid Reagent test tubes and when the timer beeps, use a

pipet to add 2mL from the digested, treated reagent hydroxide test tubes to the acid test tubes. Change tips between each sample.

13. Cap the test tubes and invert slowly ten times so they mix completely. Hold by the caps

as the test tubes will be warm. Note: Hold the tube vertical with the cap up. Invert the vial and wait for all of the solution to flow to the vial bottom. This is one inversion. Repeat 10 times. Press the soft key under START TIMER and a 5-minute reaction time will start.

14. When the timer beeps, wipe the outside of the blank test tube with a Kim wipe, place the

test tube in the spectrophotometer and close the lid. Press the soft key under ZERO and it will display 0.0 mg/L N. Repeat this zeroing intermittently between samples to ensure proper readings.

15. Calibration Check. Wipe the outside of the test tube of the Csample, and place it in the

spectrophotometer. Record this reading. Using the following equation, calculate Cspike :

(Cstd)(Vstd)+(Csample)(Vsample)=(Cspike)(Vspike) Where: Cstd = approximately 10 mg/L (Use the concentration of the standard as determined by the HACH spectrophotometer) Vstd = 5 mL Csample = The concentration of the sample chosen to create the spike, in mg/L Vsample = 20 mL Vspike = 25 mL Note: Volumes of the standard/sample may be altered at any given time based on conservation of sample requirements. These changes will be included in the results. 16. Wipe the outside of the test tube of the Cspike mixture, and place it in the

spectrophotometer. Record this number as the actual Cspike. Now, calculate the percent difference using the following equation:

% Difference = Cspike (calculated) – Cspike (actual) * 100% Cspike (calculated) 17. In order to proceed, the % difference must fall within the range of ±20%. 18. The duplicate samples must also fall within 20% of each other to be considered valid.


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19. Wipe the outside of each sample test tube, place in the spectrophotometer, close the lid and record the concentration of Total Nitrogen for each. Remember to zero between samples for the most accurate results.


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10.0. Data Analysis and Calculations

10.1 – TOT P HACH DR/4000 Calibration Check Sheet HACH DR/4000 Spectrophotometer Calibration Check Sheet Date:______________ Calibration Check Performed by:________________ Total Phosphorus Method 8190 (0.0 to 3.50 mg/L PO4

3-) Spikes Spike Sample ID Concentration(Csample) (mg/L PO4

3- ) Equation (Solve for Cspike) (Cstd)(Vstd)+(Csample)(Vsample)=(Cspike)(Vspike)

Where: Cstd = Approximately 1.00 mg/L PO4

3- (Use the concentration of the standard determined by the HACH) Vstd = 5 mL Csample = the concentration of the sample chosen to create the spike, in mg/L Vsample = 20 mL Vspike = 25 mL

Calculated Concentration Cspike (mg/L PO4

3-) Actual Concentration Cspike (mg/L PO43-)

% Difference = Cspike (calculated) – Cspike (actual) * 100% Cspike (calculated)

% Differenence: % % Difference is within 20 % [ ]. If % Difference is not within 20 %, the calibration will be repeated [ ].


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Duplicates Duplicate Sample ID Concentration 1st Run (CDUP1) (mg/L PO4

3-) Concentration 2nd Run (CDUP2)(mg/L PO43-)

The duplicate sample readings are within 0.10 mg/L of one another [ ]. If duplicate sample readings do not fall within 0.10 mg/L of one another, the calibration will be repeated [ ]. HACH DR/4000 Spectrophotometer Data Entry Sheet Date:_______________ Recorded By:________________ Storm Event:_____________ Total Phosphorus (1) Method 8190 (0.0 to 3.50 mg/L PO4

3-)

Sample ID Phosphorus Concentration (mg/L PO43-)

Standard (Approximately 1.00 mg/L PO43-

)

Spike (Standard + ____________ ) Duplicate Sample Reading #1 ( ________) Duplicate Sample Reading #2 ( ________) (1) The determined Method Detection Limit (MDL) for Total Phosphorus is 0.06 mg/L. All samples that display a concentration below the MDL will be entered into the database as ND (not detected). Any spikes that contain a sample that reads below the MDL will be considered valid if the standard reads within 20% of its known value (1.00 mg/L PO4

3-).


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10.2 – TOT ORTHO-P HACH DR/4000 Calibration Check Sheet HACH DR/4000 Spectrophotometer Calibration Check Sheet Date:______________ Calibration Check Performed by:________________ Total Orthophosphate Method 8048 (1.0 to 2.500 mg/L PO4

3-) Spikes Spike Sample ID Concentration(Csample) (mg/L PO4

3- ) Equation (Solve for Cspike) (Cstd)(Vstd)+(Csample)(Vsample)=(Cspike)(Vspike)

Where: Cstd = Approximately 1.000 mg/L PO4

3- (Use the concentration of the standard determined by the HACH) Vstd = 5 mL Csample = the concentration of the sample chosen to create the spike, in mg/L Vsample = 20 mL Vspike = 25 mL

Calculated Concentration Cspike (mg/L PO4

3-) Actual Concentration Cspike (mg/L PO43-)


% Differenence: % % Difference is within 20 % [ ]. If % Difference is not within 20 %, the calibration will be repeated [ ]. Duplicates


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Duplicate Sample ID Concentration 1st Run (CDUP1) (mg/L PO4

3-) Concentration 2nd Run (CDUP2)(mg/L PO43-)

The duplicate sample readings are within 0.020 mg/L of one another [ ]. If duplicate sample readings do not fall within 0.020 mg/L of one another, the calibration will be repeated [ ]. HACH DR/4000 Spectrophotometer Data Entry Sheet Date:_______________ Recorded By:________________ Storm Event:_____________ Total Orthophosphate (1) Method 8048 (1.0 to 2.500 mg/L PO4

3-)

Sample ID Orthophosphate Concentration (mg/L PO43-)

Standard (Approximately 1.000 mg/L PO43-)

Spike (Standard + ____________ ) Duplicate Sample Reading #1 ( ________ ) Duplicate Sample Reading #2 ( ________ ) (1) The determined Method Detection Limit (MDL) for Total Orthophosphate is 0.045 mg/L. All samples that display a concentration below the MDL will be entered into the


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database as ND (not detected). Any spikes that contain a sample that reads below the MDL will be considered valid if the standard reads within 20% of its known value (1.000 mg/L PO4

3-).

10.3 – TOT N HACH DR/4000 Calibration Check Sheet HACH DR/4000 Spectrophotometer Calibration Check Sheet Date:______________ Calibration Check Performed by:________________ Total Nitrogen Method10071 (2.0 to 25.0 mg/L N) Spikes Spike Sample ID Concentration(Csample) (mg/L N) Equation (Solve for Cspike) (Cstd)(Vstd)+(Csample)(Vsample)=(Cspike)(Vspike)

Where: Cstd = Approximately 10 mg/L N (Use the concentration of the standard determined by the HACH) Vstd = 5 mL Csample = The concentration of the sample chosen to create the spike, in mg/L Vsample = 20 mL Vspike = 25 mL

Calculated Concentration Cspike (mg/L N) Actual Concentration Cspike (mg/L N)


% Differenence: % % Difference is within 20 % [ ]. If % Difference is not within 20 %, the calibration will be repeated [ ].


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Duplicates Duplicate Sample ID Concentration 1st Run (CDUP1) (mg/L N) Concentration 2nd Run (CDUP2)(mg/L

N) The duplicate sample readings are within 0.1 mg/L of one another [ ]. If duplicate sample readings do not fall within 0.1 mg/L of one another, the calibration will be repeated [ ]. HACH DR/4000 Spectrophotometer Data Entry Sheet Date:_______________ Recorded By:________________ Total Nitrogen (1) Method10071 (2.0 to 25.0 mg/L N)

Sample ID Nitrogen Concentration (mg/L N) Standard (Approximately 10 mg/L N) Spike (Standard + ____________ ) Duplicate Sample Reading #1 ( ________ ) Duplicate Sample Reading #2 ( ________ )


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(1) The determined Method Detection Limit (MDL) for Total Nitrogen is 1.7 mg/L. All samples that display a concentration below the MDL will be entered into the database as ND (not detected). Any spikes that contain a sample that reads below the MDL will be considered valid if the standard reads within 20% of its known value (10 mg/L N).

11.0. Waste Management Note: Vials are not reusable and are disposed of as per the product’s Material Safety Data Sheet (MSDS).

12.0. References Hach Company (1998) “TenSette Pipet Model 19700-01 Instruction Manual”, Loveland,

CO. Hach Company (2000) “COD Reactor Model 45600 Instrument Manual” Fourth Edition,

Loveland, CO. Hach Company (2002) “DR/4000 Spectrophotometer Handbook” Loveland, CO. Standard Methods (1999). “Standard Methods for the Examination for Water and

Wastewater” 20th Edtion, American Public Health Association (APHA), American Water Works Association (AWWA), Water Environment Federation (WEF).

U.S. Environmental Protection Agency (USEPA). “Urban Stormwater BMP Performance

Monitoring” U.S. Environmental Protection Agency, 2002a.

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