University of North Florida
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Stuart Chalk, Ph.D.
Department of Chemistry
University of North Florida
Phone: 1-904-620-1938
Fax: 1-904-620-3535
Email: schalk@unf.edu
Website: @unf

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NIES 9

Classification: Reference Material -> NIES -> 9 -> Sargasso

Citations 1

"Online Microwave Digestion Of Slurry Samples With Direct Flame Atomic Absorption Spectrometric Elemental Detection"
Analyst 1992 Volume 117, Issue 2 Pages 117-120
Stephen J. Haswell and David Barclay

Abstract: A flow injection system is described (with diagram) for online microwave digestion of slurried samples and AAS detection. Sample slurries were prepared in 5% HNO3 and portions (1 ml) were injected into the system and passed through a PTFE coil (20 m x 0.8 mm i.d.) in a microwave oven operated at 90% power (525 W). The digest was passed through a 5-m cooling loop in an antifreeze bath and then through a back-pressure regulator to the nebulizer of an AAS instrument. Recoveries of Mg, Ca, Zn and Fe from reference materials were 93.6 to 107%. Precision was 4 to 5%. A flow injection (FI) system for online microwave digestion of slurried samples with direct elemental determinations by flame atomic absorption spectrometry is described. Organic based elemental reference samples were prepared as slurries in 5% (by volume) HNO3 and the system was optimized for slurry mass, acid strength and tube and microwave cavity geometry. Bubble formation during digestion was controlled by post-digestion cooling and pressure regulation. Comparison of direct and FI calibrations indicated no apparent loss in sensitivity. Various samples (e.g. chlorella, mussel, sargasso, pepperbush, bovine liver reference materials) were examined and elemental recoveries for Ca, Fe, Mg, and Zn were typically found to be in the range 94-107% with precisions of less than 4.5% relative standard deviation. The major source of error was found to be in the dispersion of solids (<180 µm) as slurries in dilute HNO3. The throughput of samples in the system developed was 1-2 min per sample.
Magnesium Calcium Zinc Iron Sample preparation Spectrophotometry Microwave Online digestion Slurry Reference material