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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Leaves

Classification: Plant -> peach -> leaves

Citations 3

"Speciation Analysis Of Chromium(III) And Chromium(VI) Using Flow Injection Analysis With Fluorometric Detection"
Analyst 1998 Volume 123, Issue 5 Pages 1005-1009
Evangelos K. Paleologos, Spyros I. Lafis, Stella M. Tzouwara-Karayanni and Miltiades I. Karayannis

Abstract: A relatively simple, sensitive, selective, automatic fluorometric method for the simultaneous determination of Cr(III) and Cr(VI) by flow injection analysis (FIA) was developed. The method is based on the selective oxidation of the nonfluorescing reagent 2-(α-pyridyl)thioquinaldinamide (PTQA), which with Cr(VI) yields an intensely fluorescent product (λex = 360 nm; λem = 500 nm). Cr(III) is oxidized online to Cr(VI) with sodium metaperiodate and the Cr(VI) is subsequently treated with PTQA. Fluorescence due to the sum of Cr(III) and Cr(VI) is measured and Cr(III) is determined from the difference in fluorescence values. The effects of various anal. parameters, such as acidity, flow rate, sample volume, temperature, reagent concentration and interfering species, were studied. Kinetic studies using both the stopped-flow technique and the FIA procedure were used to study and optimize the oxidation conditions for Cr(III) from its oxidation efficiency. The calibration graphs were rectilinear in the ranges 0.1-10 µg mL-1 for Cr(VI) and 0.1-1.0 µg mL-1 for Cr(III). The method was successfully verified by performing recovery experiments of Cr in several standard reference materials (peach leaves, sediments and tea), and it was applied to the speciation analysis of Cr(III)-Cr(VI) in environmental waters (mineral, tap and distilled water), a food sample (tomato juice) and synthetic mixtures. Up to 30 samples per h can be analyzed with a relative standard deviation of ~0.1-2%.
Chromium(III) Chromium(VI) Fluorescence Speciation Stopped-flow Kinetic Reference material Indirect Interferences Optimization

"Determination Of Trace Mercury In Environmental And Biological Samples By Flow Injection Hydride-generation Graphite-furnace AAS"
Guangpuxue Yu Guangpu Fenxi 1993 Volume 13, Issue 5 Pages 107-110
Ma, Y.P.;Gulikezi;Fang, X.H.

Abstract: Pre-treated sample (500 µL) was injected and carried by a stream of water (6 ml/min) to react with streams of 5 M HCl and 0.3% KBH4 (both at 1 ml/min). After passing through a gas-liquid separator, the generated Hg was carried by Ar at 50-80 ml/min to a self-made Au-coated graphite-furnace for AAS, with pre-concentration and atomization temperature of 45-160°C and 500°C and 600°C, respectively. By standard-additions method, recovery was 98-101%; RSD were 5-10%. The calibration graph was linear with a detection limit of 20 pg of Hg. The method was applied to assay of human hair, urine, soil and peach leaf. No interference was observed from co-existing ions. Sampling rate was 50 runs per h.
Mercury Spectrophotometry Interferences Preconcentration Standard additions calibration

"Flow Injection Analysis - Kinetic Method For The Determination Of Traces Of Zinc With Meso-tetra-(4-sulfophenyl)porphyrin"
Lihua Jianyan, Huaxue Fence 1992 Volume 28, Issue 3 Pages 170-172
Peng, X.J.;Mao, Q.K.;Cheng, J.K.

Abstract: The cited method was based on the measurement of the absorbance due to the formation of Zn - meso-tetra-(4-sulfophenyl)porphyrin (I) complex using imidazole (II) as catalyst. The reagent solution was prepared by mixing 0.5 mL of 10.2 mM I, 2 mL of Na acetate - acetic acid buffer solution (pH 4.8) and 2 mL of 0.55% II. Portions (25 µL each) of the reagent solution and the sample solution containing 1 µg mL-1 of Zn were subjected to flow injection analysis (at 85°C) with redistilled water as carrier solution (2 mL min-1) and absorbance measured at 424.4 nm after stopping the flow for 60 s. Calibration graph was rectilinear for up to 2.5 µg mL-1 of Zn. The coefficient of variation (n = 16) was 0.8% for 1 µg mL-1 of Zn. Tolerance levels of 17 foreign ions were tabulated. The method was used to determine trace Zn in hair, tap water and peach leaves. Results agreed with those obtained by ICP-AES.
Zinc Spectrophotometry Kinetic Complexation Method comparison Catalysis Interferences Stopped-flow