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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Phosphate

Classification: Geological -> ore -> phosphate

Citations 2

"Simultaneous Determination Of A Binary Mixture: Kinetic Method For Determination Of Uranium And Vanadium"
Analusis 1993 Volume 21, Issue 10 Pages 421-424
Jianhua, W.; Ronghuan, H.

Abstract: The flow injection method was based on the kinetic differences of the catalytic effects of U(IV) and V(IV) on the oxidation of I- by Cr(VI). All solution were adjusted to pH 2 with HCl. Sample solution in 0.1% starch (20 µL) were injected into the carrier solution of 0.1% starch (3.2 ml/min), which was mixed in a PTFE coil (30 cm x 0.5 mm i.d.) with 18 mM KI solution (3 ml/min). This solution was further mixed with 1.6 mM Cr(VI) solution (3 ml/min) in a second coil (15 cm x 0.5 mm i.d.) and transferred to the stop-flow cell. Absorbances were measured at 590 nm at 15 s and 30 s after stopping the flow. Equations are given for calculating the U(IV) and V(IV) concentrations. Calibration graphs were linear for 0~3.6 µg/ml of U(IV) and 0~2.5 µg/ml of V(IV), with detection limits of 0.024 and 0.01 µg/ml, respectively. Of 20 cations tested, only Fe(II) and Sb(III) interfered seriously, with an error of 5% at 1 µg each of the analytes and 1 µg of the interferents. The method was tested on synthetic samples and a phosphate ore; the results were comparable with those obtained by AAS. RSD were 1.7-4.8%.
Uranium Vanadium Kinetic Interferences Stopped-flow

"Kinetic Spectrophotometric Method For Simultaneous Determination Of Uranium, Iron And Vanadium With A Stopped-flow Technique"
Chem. Anal. 1993 Volume 38, Issue 4 Pages 497-504
Jianhua, W.;Ronghuan, H.

Abstract: Sample solution was injected into a carrier stream of aqueous 0.1% starch solution of pH 2 (3.2 ml/min) and the stream was merged with a stream (3 ml/min) of 18 mM KI before passing through a reaction coil (30 cm x 0.5 mm). The resulting stream was merged with a stream of 1.6 mM potassium dichromate of pH 2 and after passing through a second coil (15 cm x 0.5 mm) the stream was driven into the flow cell and stopped. The presence of the analytes induced a reaction between Cr(VI) and iodide, which was indicated by the formation of the colored I3-starch complex. The absorbance of this complex was monitored at 590 nm at 10, 20 and 30 s from the stop of the flow. The calibration graphs were rectilinear up to 3.6, 2.8 and 2.5 µg/ml for U, Fe and V, respectively, with corresponding recoveries of 95.1%, 104.8% and 96.7% and detection limits of 0.024, 0.08 and 0.01 µg/ml. Only Sb(III) and Ti(III) interfered. The method was applied to the simultaneous determination of U, Fe and V in phosphate ore and a synthetic sample (details given), with RSD from 3.9-5.1% and 3.6-5.6%, respectively.
Uranium Iron Vanadium Spectrophotometry Kinetic Stopped-flow Interferences