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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High purity

Citations 3

"Electrothermal Atomic Absorption Spectrometric Determination Of Molybdenum In Water, Human Hair And High-purity Reagents With Flow Injection Online Coprecipitation Preconcentration"
J. Anal. At. Spectrom. 1995 Volume 10, Issue 8 Pages 533-537
Hengwu Chen, Shukun Xu and Zhaolun Fang

Abstract: Hair (0.1 g) was digested with 5 mL 70% HNO3 and 1 mL 70% HClO4 on a sand-bath at 120-150°C to near-dryness. After cooling, the residue was dissolved in 5 mL 4 M HCl and 5 mL Fe(II) solution (500 mg/l) containing 2% ascorbic acid (sufficient to reduce any trivalent Fe present) was added. The solution was diluted to 50 mL with water and portions were injected into a stream of 0.4 M HCl (1.7 ml/min) of a flow injection system (schematic shown) and mixed with a stream of 0.25% ammonium pyrrolidinedithiocarbamate solution (0.3 ml/min). The precipitate formed [Mo-Fe(II) pyrrolidinedithiocarbamate] was collected on the walls of a knitted reactor and dissolved in 50 µL MIBK. The MIBK concentrate zone was directly introduced into the GF (program details given) with Ar carrier gas (300 ml/min) and the absorbance was measured at 313.3 nm for Mo by AAS. The detection limits were 0.04 and 0.02 µg/l of Mo, respectively, for a 30 and 60 s loading times. RSD was 3.1% at 1.3 µg/l of Mo and recoveries of spiked Mo in tap water, seawater and sodium chloride reagent were 94-104%. Results obtained from the analysis of Mo in a human hair certified reference material agreed well with the certified value.
Molybdenum Spectrophotometry Coprecipitation MIBK Preconcentration Reference material Knotted reactor

"Iodide Selective Electrode In Flow Injection System"
Analusis 1988 Volume 16, Issue 9-10 Pages 101-104
Ilcheva, L.K.;Cammann, K.;Georgieva, T.

Abstract: Baseline drift that occurred during use of the I--selective electrode [Seibold 57-17 (Radelkis)] in presence of a high Cl- concentration. could be avoided by use of a flow injection system with the addition of ascorbic acid to the carrier stream. Thus, 50 ppm of I- in high-purity NaCl could be determined by flow injection analysis in a carrier stream (1.7 mL min-1) of 0.1 M NaNO3 containing 0.1 mg L-1 of ascorbic acid with use of the cited electrode. No interference from Cl- memory effects could be detected.
Iodide Electrode Drift Interferences

"Microscale Ion-exchange Separation And Flow Injection Catalytic Determination Of Manganese In High-purity Sodium Chloride"
Nippon Kaisui Gakkaishi 1989 Volume 43, Issue 1 Pages 48-53

Abstract: A technique for microscale ion-exchange separation of manganese at 0.1 ng levels was developed and combined with flow-injection spectrophotometry based on manganese-catalyzed oxidation of malachite green with periodate. A sample (0.2 to 1.5g) was dissolved in less than 4.5 ml of a 0.04 M ammonia - 0.16 M ammonium chloride buffer solution (pH 9). The solution was then passed through a chelate resin µcolumn of 20 µl capacity (Dowex A-1, 50 to 100 mesh) to adsorb manganese and to remove the interfering matrix salt. The adsorbed manganese was eluted with 0.3 ml of 2 M nitric acid. A column of 10 µL capacity could be used for less than 1 ml of the sample solution. After evaporation of the effluent, the residue was dissolved with 0.1 M acetate buffer solution (pH 4.4), and a 100 µL aliquot was injected into a flowinjection system. The reduction of absorbance of malachite green was measured at 615 nm after reaction for 6.5 min at 50°C. Manganese of ppb levels in high purity salt is determined within a standard deviation of about 0.1 ppb.
Manganese Ion exchange Spectrophotometry Catalysis Preconcentration Interferences