analytical considerations for high performance (fertilizer
TRANSCRIPT
www.spectro.com
Analytical considerations for
High Performance (fertilizer) analysis
using ICP-OES
www.spectro.com
• Lowest detection limits
• OPI: up to 20% TDS
• Higher flexibility
• Larger linear range
• Less matrix effects
• Easier handling
• Best stability
Radial and Axial Plasma Orientation
www.spectro.com
Tools affecting the Quality of your Analysis
• Spectrometer Design
– Optic (Resolution + Stability + Sensitivity)
– Generator (Stability)
– Plasma Orientation (radial or axial)
– Detector (Stability + Sensitivity)
• Software
– Use of Internal Standard
– Bracketing
– DMC (Dynamic Measurement Correction)
– Typestandardization
www.spectro.com
Considerations – Optical System
Better line separation in line rich spectra
Minimization of spectral Interferences
Simplified method with line rich matrices
Improved accuracy
Analyze halogens and use a multiplicity of un-interfered lines
Full sensitivity for all elements
www.spectro.com
Example resolution
6
Higher accuracy in line
rich matrices
Al 168 nm
Cd 214 nm
8 pm Resolution 23 pm Resolution
www.spectro.com
Best transparency in the spectral range < 180 nm
8
Element Interfered line above 180 nm (nm) Interferer* Interference free line in the VUV (nm) Application
Al 394.401; 396.152 Ca 167.080, 172.498 Water, mineral w ater, sludge
396,152 Ce, Mo 167,080 Rare earths, Mo alloys
Au 267,595 Cr 174,047 Geological samples
Bi 190.241; 222.885; 306.772 Ce 153,317 Rare earths
B 182.590; 208.892; 249.677; 249.773 U 136,246 nuclear materials
Ga 287.424; 294.364; 403.299; 417.204 Fe, U 141,444 Soil, Fe and Fe alloys, uranium oxide
Ge 265,911 Cr, Pt, Zr 164,919 Metals
I 183,038 Fe, Al, Ca 142,549 Water, w aste w ater
In 230.606; Co, Pt, Pd, Ca, Rh 158,583 Precious metals
230.606; 303.936; 325.609 Fe 158,583 Geological samples
P 213.618; 253.565 Cu 178.287; 138.147 Brass, Cu alloys
Pb 220,351 Pd; Ni, Al 168,215 Precious metals, steel, Ni alloys
220.351; 261.418; 283.307; 405.785 Th 168.215; 143.389 nuclear materials
Pt 265.949, 212.861 Ni, Co, Ca 177,709 Precious metals
S 180.731; 182.034 W 142.503; 143.328 W alloys
Si 212.412; 251.612; 288.158 W 152.672; 126.473 W w ires
Sn 189,991 Pt, Zr, Pd 147.515; 140.052 Precious metals , electronic w aste materials
189,991 Al 140,052 Soil, Al alloys
189.991; 242.949;187.115; 181.134 Rh, U 147.515; 140.052 Nuclear materials, precious metals
Te 214.281; 214.725 Cu, Zn, Al 170,000 Brass, Cu alloys
Tl 190.864; 276.787 W 132,171 W alloys
190,864 Ti, U 132,171 Pigments, soil, nuclear materials
www.spectro.com
Generator consideration
9
• Short stabilization time
• Long term accuracy/precision
• Added power range compared
to the tube generator
www.spectro.com
98.000
98.500
99.000
99.500
100.000
100.500
101.000
101.500
102.000
102.500
103.000
QC- 0
QC- 1
QC- 2
QC- 3
QC- 4
QC- 5
QC- 6
QC- 7
QC- 8
QC- 9
QC- 10
QC- 11
QC- 12
QC- 13
QC- 14
QC- 15
QC- 16
QC- 17
QC- 18
QC- 19
QC- 20
QC- 21
QC- 22
QC- 23
QC- 24
Reco
very
[%
]
8 hour recovery test for Au, Pt, Pd, Rh ARCOS SOP with Seaspray nebulizer
Au 267.595 (Sc) 0.175 % RSD
Pt 265.945 (Sc) 0.157 % RSD
Pd 340.458 (Sc) 0.182 % RSD
Rh 343.489 (Sc) 0.192 %RSD
www.spectro.com
Software I - Using Internal Standard
• Compensation of non-spectral interferences
- Viscosity
- Pump tubing
- Difference in Salt content
- Vapor pressure
to Improve the precision of your measurements
www.spectro.com
Au Sc Au/Sc
Time
Rela
tive I
nte
nsit
y
Internal Standard Au 267 – Sc 361
Software - I
Using Internal Standard
www.spectro.com
Software - II
Bracketing
• Highest precission
• Sample get “Bracked”
by calibration Std
• Analysis time approx.
20 min per sample
Measure Sequence: Low – Unkn (1) – High – Unkn (2) -Low – Unkn (3) – High – Unkn (4) -Low – Unkn (5) – High
0
50000
100000
150000
200000
250000
300000
350000
400000
450000
0 10 20 30 40 50
www.spectro.com
Bracketing analysis
High precision and
accuracy:
Result:
82,37 mg/L Pt 0,055 mg/L SD
0,067 % RSD
Bracketing
79.7 [mg/L]
100.03 [mg/L]
5
Medium values n 5
Y Pt
Std 3 72205 0.8002
Sample 5 66577 0.8273
Std 5 72196 1.0018
Sample 5 66696 0.8280
Std 3 72394 0.8018
Sample 5 66849 0.8288
Std 5 71937 1.0036
Sample 5 66457 0.8285
Std 3 72042 0.8028
Sample 5 66021 0.8289
Std 5 70650 1.0038
Sample 5 82.43 [mg/L]
Sample 5 82.36 [mg/L]
Sample 5 82.42 [mg/L]
Sample 5 82.30 [mg/L]
Sample 5 82.34 [mg/L]
Average 82.37 [mg/L]
SD 0.055 [mg/L]
RSD 0.066 [%]
Std 3 = Low concentration
Std 5 = High concentration
Bracketing cycles
Software - II
Bracketing
www.spectro.com
Software - II
Bracketing
• Select method to work with
• Select global instrument
parameter
• Select “Leading Element” for
Bracketing
• Select number of Cycles (typically
5)
www.spectro.com
Software - III
Dynamic Measurement Correction (DMC)
• DMC can be used to correct drift over time
• Use a “Point to Point” regression or
• Use a “Linear over all Points” regression
• Any line can be paired with any Control-Standard
• Calculation is based on Concentration
30
40
50
60
70
80
90
0 5 10 15 20 25 30 35 40 45
www.spectro.com
Software - III
Dynamic Measurement Correction (DMC)
• Select method and
calculation model
• Pair line and Ctrl
• Make sure that a Ctrl is
analyzed at Begin and
End of the run
www.spectro.com
Software - IV
Type Standardization
• To correct species-specific effects
• Can be combined with DMC
• The initial Ctrl is used to build a correction-factor
• Each result will be multiplied (corrected) with this factor
