Post on 16-Nov-2020
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Elemental Scientific prepFAST: Geo-Chem Fire AssayPrecious Metals by ICPOES
Features:
• Autocalibrate from a single stock standard
• Autodilute sample digests (50% acid)
• Automate hazardous labor intensive steps
• Fluoropolymer sample pathway
• High speed analysis (<1 min/sample)
• Reduce cost per analysis
• Routine walk up and analyze solution for ICP and ICPMS
Brief
The prepFAST inline autodilution system autocalibrates and autodilutes 50% Aqua Regia samples for the precise and accurate determination of precious metals. Seamless integration of prepFAST with ICP software eliminates a hazardous manual dilution step that requires both time and additional reagents/tubes.
Authors: Austin Schultz, Kyle Uhlmeyer and Paul Field (fi eld@icpms.com)
Figure 1. prepFAST automatically generates a 0.2 (25x), 0.5 (10x), 2.5 (2x) and 5.0 (1x) calibration curve from a 5 ppm Au, Ir, Os, Pd, Pt, Rh, and Ru (5% HCl/5% HNO3) stock standard solution. Precise and accurate syringe based inline autodilution is illustrated through excellent linearity of all calibration curves.
Element R2
Ru 0.99998
Rh 0.99998
Pd 0.99998
Os 0.99998
Ir 0.99995
Pt 0.99996
Os Autocalibrati on from 5 - 0.2 ppm
Os 228.226
0.2ppm
Element R2
Ru 0.99998
Rh 0.99998
Pd 0.99998
Os 0.99998
Ir 0.99995
Pt 0.99996
R2 = 0.99998
0.5ppm
2.5ppm
5.0ppm
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Abstract
Fire assay is one of the oldest known techniques for purifying precious metals. Typically Ni (Au, Ir, Os, Pd, Pt, Rh, and Ru) or Pb (Au, Pt and Pd) are used to scavenge precious metals from their matrix during fusion. The resultant sulfide bead and extracted precious metals are then digested in strong mineral acids (50% Aqua Regia). Using prepFAST, sample digests (50% Aqua Regia) can simply be placed on the autosampler rack with a blank and a 5 ppm multi-element (Au, Ir, Os, Pd, Pt, Rh, and Ru) stock standard. The prepFAST system will automatically generate a 0.2 (25x), 0.5 (10x), 2.5 (2x) and 5.0 (1x) calibration curve and analyze samples at a rate of nearly 90/hr.
Vacuum
Diluent
Carrier
InternalStandard
Rinse
To ICPMSP7+ Inject/Dilute
InternalStandard
Diluent
Carrier
Sample
Vacuum
To ICPMSP7+ Load
Figure 2. The prepFAST system schematic illustrating 1) sample loading during spray chamber rinse and 2) sample injection dilution and internal standardization.
Figure 3. Typical 10 mL sample volumes at 20x dilution factor would require 9.5 mL of diluent. prepFAST saves reagent by only diluting the volume of sample being analyzed. In this experiment (20x dilution) prepFAST uses only0.5 mL of diluent per sample. Depending on number of reagents, reagent concentration and purity this 19x reduction in diluent represents a significant savings.
Diluent Use Comparison – Manual vs. Autodilution
20X Manual Dilution3%HNO3
20X Inline Autodilution3%HNO3
123456 123456
DigestedSample
10mLDilutedSample
10mLMixedSample
ManualMixingRequired
NoMixingRequired
9.5mL3%HNO3
Diluent3%HNO3
0.5mLSample
800µL/min 800µL/min
760µL/min
40µL/min
DigestedSample
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Figure 4. A 5ppm Au, Os, Ir, Pt, Pd, Rh, and Ru sample prepared in 50% Aqua Regia simulates a fi re assay digestion. The concentrated mineral acid solution is diluted 20x inline for 700 replicate sample analysis of 0.25 ppm of precious metals. prepFAST inline autodilution illustrates not only a rapid throughput at 88 samples per hour, but also very accurate reproducible results for a 50% Aqua Regia matrix.
Sample Stability
0.00
0.10
0.20
0.30
0.40
0.50
0 60 120 180 240 300 360 420 480
Concen
tra)
on Fou
nd (p
pm)
Time (Minutes)
Rh concentra)on in 700 samples over 8 hours. RSD ≤ 2%
50% Aqua Regia20x Inline autodiluti on
88 sample/hr
Figure 5. Recovery based on the 700 analysis of 0.25 ppm precious metal is both quantitative (101 to 106%) and precise (<3%).
Recovery
102% 105% 101% 104% 104% 102% 106%
0%
50%
100%
150%
200%
Au 267.595 Ir 224.268 Os 228.226 Pd 340.458 Pt 265.945 Rh 343.489 Ru 240.272
Percen
t Recovery
Element
Recovery 101% -‐ 106%
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SC-2 DX prepFAST System
1500 North 24th Street | Omaha, NE 68110 USA
Phone: 1.402.991.7800 | Fax: 1.402.991.7799
Email: prepFAST@icpms.com
Web: www.prepFAST.com | www.icpms.com Elemental Scientific
Benefi ts:
• Reduce cost per analysis through inline sample dilution Cut sample time in half
Reduce the amount of diluent (by 20x)
Reduce the number of vials (by half)
Eliminate hazardous (50% Aqua Regia) manual sample dilution step
Eliminate pump tubing, consumables, and maintenance
• Simply place rack with digested samples on the autosampler and run