1 Brief The FAST Flame is a fully automated sample introduction system for the Flame AA (Atomic Absorption). Preparation and analysis time are greatly reduced when working with both the aliiix pump (for rapid and consistent dispensing of Mehlich 3 extraction solution) and the prepFAST offline system (automatically dilutes the extractant, bringing samples within the instrument’s analytical range). Authors: Andrew Kavan ([email protected]), Kyle Uhlmeyer and Kevin Hahn. Elemental Scientific Rapid Preparation and Analysis of Soil Samples by FAA Elemental Scientific Features: • aliiix: ü Dispensed volume is adjustable from <1 mL/cycle to >40 mL/cycle ü Metal-free flow path ü Dual fluoropolymer check valves ü Handheld triple sample dispenser (aliiix 50x3) • prepFAST Offline: ü Fully automated ü Syringe-driven sample handling—sample never enters syringes ü Syringe delivery of diluent ü Probe rinse between every sample • FAST Flame: ü Fully automated sample introduction system ü Up to 560 samples/hour ü Fluoropolymer pathways ü No sample contact with peripump tubing aliiix 50x3 triple reciprocating pump with handheld sample dispenser Figure 1. After soil is added to bottles, 20 mL of Mehlich 3 extracting solution is rapidly added by the aliiix pump.
Transcript
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BriefThe FAST Flame is a fully automated sample introduction system for the Flame AA (Atomic Absorption). Preparation and analysis time are greatly reduced when working with both the aliiix pump (for rapid and consistent dispensing of Mehlich 3 extraction solution) and the prepFAST offline system (automatically dilutes the extractant, bringing samples within the instrument’s analytical range).
Authors: Andrew Kavan ([email protected]), Kyle Uhlmeyer and Kevin Hahn.
Elemental Scientific Rapid Preparation and Analysis of Soil Samples by FAA
Elemental Scientific
Features:
• aliiix:
ü Dispensed volume is adjustable from <1 mL/cycle to >40 mL/cycle ü Metal-free flow path ü Dual fluoropolymer check valves ü Handheld triple sample dispenser (aliiix 50x3)
• prepFAST Offline: ü Fully automated ü Syringe-driven sample handling—sample never enters syringes ü Syringe delivery of diluent ü Probe rinse between every sample
• FAST Flame: ü Fully automated sample introduction system ü Up to 560 samples/hour ü Fluoropolymer pathways ü No sample contact with peripump tubing
aliiix 50x3 triple reciprocating pump with handheld sample dispenser
Figure 1. After soil is added to bottles, 20 mL of Mehlich 3 extracting solution is rapidly added by the aliiix pump.
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Abstract
A new automated procedure for multi-element soil analysis by flame atomic absorption (FAA) is described. Two grams of soil are weighed and placed in a 125 mL plastic bottle for Mehlich 3 extraction. The sample preparation procedure involves, 1) addition of 20 mL of Mehlich 3 extractant, 2) 5 minutes of mixing, and 3) filtration of extractant (Whatman grade 2 filter paper). 1 mL of sample filtrate is aliquoted into a vial for offline (20x) autodilution. The undiluted sample is measured for low concentration metals (Cu, Mn, Na and Zn) by FAA while the 1 mL fraction is autodiluted for the determination of higher concentration metals (Ca, Fe, K and Mg). After the first group of metals is analyzed, the second set of autodiluted samples is ready. Samples are introduced using a high throughput introduction system that utilizes an injection valve to rapidly load (vacuum) and inject (peripump) the samples into the flame. Using this fast sample introduction system, throughput is approximately 8 seconds per sample for each analyte. Combining offline autodilution and inline fast analysis provides accurate and precise data for 8 analytes in roughly 1 min per sample. This procedure offers a low-cost, simple FAA alternative for soil analysis to ICP.
Table 1. Compares the time needed to fill every vessel with Mehlich 3 extractant for each aliiix model for 60 samples and 120 samples
aliiix Model 60 samples 120 samples
50x1 86 sec 171 sec
50x3 29 sec 57 sec
Figure 2. 20 mL Dispensed at various speeds.
aliiix Reproducibility
0.23% 0.22%
0.33%
0.63%
0.00%
0.10%
0.20%
0.30%
0.40%
0.50%
0.60%
0.70%
6 20 35 42
Rela%v
e stan
dard devia%o
n (%
)
Cycles per minute
Reproducibility of Volume Dispensed per Cycle
After mixing the samples for 5 minutes, the samples are filtered using Whatman grade 2 filter paper.
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Dilution of Samples with High Accuracy and Precision
3.0
3.5
4.0
4.5
5.0
5.5
6.0
Cu Mn
Concen
tra)
on (p
pm)
5.04 ±0.9% n=55
5.03 ±1.2% n=55
55 Samples Diluted in 1 hour (20x dilution)
Figure 3. 100 ppm samples were autodiluted (20x) 55 times using the prepFAST Offline system and analyzed by ICP.
prepFAST Offline System
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Figure 5. Inject sample aliquot into a peristaltic pump-driven carrier liquid at 5 mL/min (2s) and read absorbance (2s).
Inject Sample
Figure 4. Vacuum load sample into valve loop located near the AA spray chamber (1s).
Figure 6. Quick stabilization and washout: After the loop is loaded, the valve switches to inject. The sample is pushed by the carrier solution into the spray chamber and analyzed by the instrument. Once analysis is completed, the valve switches back to the load position, rinsing the nebulizer and spray chamber.
Absorbance Time Profile for 5 Replicate Injections of 100 ppm Cu
45 s
Table 2. Flame AA Analysis of 10 Solutions (Calibration, 3 Blanks and 3 Samples) in 75 seconds with > 600x* washout between samples.
Concentra)on Time Cu 324.75 (ppm)
Cal Blank 1:37:43 PM 0.00
1 ppm 1:37:51 PM 1.00
2 ppm 1:37:59 PM 2.00
6 ppm 1:38:07 PM 6.00
Blank 1:38:15 PM 0.01 *
Blank 1:38:24 PM -‐0.00
Blank 1:38:33 PM -‐0.01
2 ppm 1:38:41 PM 2.04
2 ppm 1:38:50 PM 2.03
2 ppm 1:38:58 PM 2.06
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20-Hour Stability
Average Concentration: 2.00 ± 1.84%
Average Analysis Time: 8.2 Seconds
0 20 40 60 80 100 120 140
0.00
0.50
1.00
1.50
2.00
2.50
0 200 400 600 800 1000
Time (min)
Conc. C
u (ppm
)
Replicate #
2-Hour Stability
Stability for Valve Injection
Figure 7. 1000 samples of 2 ppm Cu performed in 2 hours and 17 minutes (8.2 s/sample). Mean: 2.00 ± 1.84%.
Figure 8. n = 8931, Average = 2.01 ppm, RSD = 2.1% over 20 hours
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% Recovery in Soil Samples by Mehlich 3 Extraction
Figure 9. Compares the spiked recoveries for each analyte. Average recovery is 97%. The set of samples is analyzed multiple times, once for each element. CRM is NAPT Program 2012-110.
100 97 103 94 91 97 96 99
0
20
40
60
80
100
120
140
Cu Mn Zn Na K Fe Ca Mg
% Recovery
60 Samples Run in 80 Minutes
Average Recovery > 97%
Undiluted Diluted 20x in ̴60 minutes
FAST Flame system on PinAAcle 900F
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7277 World Communications Drive | Omaha, NE 68122 USA
