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
Website: @unf

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Classification: Waste -> sludge

Citations 2

"Determination Of Selenium In Solid Samples By Continuous Subcritical Water Extraction, Flow Injection Derivatization And Atomic Fluorescence Detection"
J. Anal. At. Spectrom. 1998 Volume 13, Issue 8 Pages 787-791
C. M. Rico Varadé and M. D. Luque de Castro

Abstract: A method for the determination of selenium in solid samples is proposed. The method involves two main steps: (a) continuous leaching of the analyte by subcritical water (250°C, 200 bar, 0.7 mL min-1), which is complete in 15 min and (b) continuous derivatization (hydride formation) and detection by atomic fluorescence. The design of the derivatization manifold, based on flow injection, enables speciation anal. of inorganic selenium (as Se(IV)/Se(VI)) and organo-selenium compounds by appropriate selection of the reagent streams. Both conversions of organic into inorganic Se by oxidation and reduction of the Se(VI) formed as well as that of Se(VI) initially present in the samples to Se(IV) is accelerated by irradiation with focused microwaves using 1 m reactors and a flow-rate of 4.4 mL min-1. The linear range of the calibration curves is between 10^-50,000 ng mL-1 with relative standard deviation values <4.5%. The method was applied successfully to sludge samples from an interlaboratory study. The drastic conditions of extraction convert organic Se into inorganic, so the method does not enable inorganic-Se/organic-Se speciation in solid samples.
Selenium Fluorescence Sample preparation Volatile generation Speciation Microwave Heated reaction

"Automatic Determination Of Mercury At The Lower Ng/l Levels"
LaborPraxis 1995 Volume 19, Issue 8 Pages 32-34
Baasner, J.

Abstract: An AS 90 or 91 sample dispenser and a flow injection AAS system (FIMS 100 or 400) with a high-intensity radiation source, a long-path cuvette and a wavelength-specific detector were used in the method. The working range is 20 ng-40 µg/l of Hg and the detection limit 5 ng/l. The method was used for the analysis of Hg in rain water, urine, blood, lemon leaves and sludges. Results agreed well with certified values. When the sample is pre-concentrated by amalgamation and blank values are determined and taken into account the working range and detection limits are 1-200 and 0.3 ng/l, respectively. With the use of amalgamation recoveries of 10 ng/l of Hg added to drinking water were 98-102%. The procedure is applicable to the hydride-generation AAS determination of other elements, e.g., As, Se or Sb.
Mercury Arsenic Selenium Antimony Spectrophotometry Spectrophotometry Amalgamation FIMS Reference material Volatile generation Volatile generation