Yutaka Hayashibe

Simultaneous determination of uranium and thorium with Arsenazo III by second-derivative spectrophotometry.

A derivative spectrophotometric method has been developed for the simultaneous determination of microgram quantities of uranium and thorium with Arsenazo III in hydrochloric acid medium. The second-derivative absorbances of the uranium and thorium Arsenazo III complexes at 679.5 and 684.4 nm are used for their quantification. Uranium and thorium, both in the range 0.1-0.7 mug/ml have been determined simultaneously with good precision. The procedure does not require separation of uranium and thorium, and allows the determination of both metals in the presence of alkaline-earth metals and zirconium, but lanthanides interfere.

Determination of palladium, platinum and gold by first derivative spectrophotometry

SummaryThe application of first-derivative spectrometry to the simultaneous determination of palladium(II), platinum(IV) and gold(III) is described. Light absorption of stable chlorocomplexes formed in 1 mol/l hydrochloric acid provides the basis of their determinations. A difference in the derivative amplitudes between two first-derivative zero crossing points of one metal A is read, corrected for the contribution of metal B and used for quantitation of metal C. Palladium (0.48–20 μg ml−1), platinum (0.16–24 μg ml−1) and gold (0.32–24 μg ml−1) have been determined with good precision and accuracy without any separations. Results are also presented for the simultaneous determination of the three precious metals in the presence of several major constituents.

Determination of traces of gallium and indium in ores by electrothermal-atomization atomic absorption spectrometry with matrix modifications

Methods were developed for the determination of gallium and indium in complex ores by electrothermal-atomization atomic absorption Spectrometry using matrix modifications. Nickel and nickel-ammonium sulfate as matrix modifier has enhanced the absorption signals for gallium and indium, respectively, eliminating the matrix interferences to allow their solutions in nitric acid to be used as calibration standards. No matrix separations are necessary. Results are quoted for a variety of black ore samples (Kuroko). The RSDs are 7.0% for gallium and 5.3% for indium at their 10 μg/g levels, and the inverse sensitivities are 20 pg of gallium and 38 pg of indium for respective 1% absorption.

Determination of cadmium and bismuth in high-purity zinc metal by inductively coupled plasma mass spectrometry with on-line matrix separation

Traces of cadmium and bismuth in high-purity zinc metal were determined by inductively coupled plasma mass spectrometry (ICP-MS) in combination with flow injection (FI) on-line matrix separation (FI-ICP-MS). The anion-exchange separation method of the potassium iodide (KI) system was applied to the separation of the analytes from the matrix zinc. The analytes, cadmium and bismuth, were adsorbed on the anion-exchange (BIO·RAD AG1-X8) mini-column (1.0 mm i.d.×100 mm bed length), while the matrix zinc can be completely removed from the anion-exchange resin. The analytes were eluted by 2 mol/l HNO3 and directly introduced into the ICP-MS. The detection limits (D.L.) obtained by using a single injection (350 μl) were 0.81 and 0.075 ng g−1 for cadmium and bismuth, respectively. In the case of multi-injection concentration onto the anionexchange mini-column (five injections 350 μl each), the detection limits could be improved to 0.16 and 0.014 ng g−1 for cadmium and bismuth, respectively. The reproducibilities of the single injection and the multi-injection method were satisfactory with a relative standard deviation of less than 5% (at the 10 and 1 ng ml−1 level for the single injection and the multi-injection method, respectively). The method was successfully applied to the determination of trace impurities in four samples of high-purity zinc metal (7 nines grade) and three standard reference materials of high-purity unalloyed zinc samples (from NIST).

Determination of trace amounts of cadmium in a hydrometallurgical zinc refining process stream by a flow-injection method with on-line preconcentration and spectrophotometric detection

A flow-injection (FI) method was developed for the spectrophotometric determination of cadmium in a hydrometallurgical zinc refining process stream using 1-(4-nitrophenyl)-3-(4-phenylazophenyl)triazene (Cadion) as the chromogenic reagent. The sample solution was injected into a carrier containing potassium iodide. The sample was then passed through an anion-exchange mini-column on which the analyte was concentrated as a cadmium–iodo complex. In order to extend the detectable range of cadmium, a multiple sample injection method, in which the sample solution was repeatedly injected into the carrier at regular intervals of 30 s, was applied. Cadmium on the column was eluted with 1 mol l–1 nitric acid and merged with a stream of a mixture of masking agent (trisodium citrate–potassium sodium tartrate–potassium hydroxide) and Cadion. Finally, the absorbance of the cadmium–Cadion complex was measured at 480 nm. The proposed FI was fully controlled by a personal computer. The proposed system permitted throughputs of 6 samples h–1 for single injection, and 2 samples h–1 for single injection, and 2 samples h–1 for multiple sample injection (50 injections). The reproducibility was satisfactory with a relative standard deviation of less than 5.0%(0.14 µg ml–1 Cd level, n= 5) for the single injection method and 10%(2.0 ng ml–1 Cd level, n= 5) for the multiple sample injection method (50 injections). The detection limits were 0.028 µg ml–1 of cadmium for the single injection method and 0.83 ng ml–1 of cadmium for the multiple sample injection method (50 injections). The absolute amount of cadmium detectable, defined as the analytical signal equal to twice the uncertainty in the background, was 10 ng.

Spectrophotometric determination of cobalt in high-salt concentration solutions by flow injection method.

フローインジェクション法により,高塩濃度溶液中(亜鉛電解用硫酸亜鉛溶液)の0.1μg ml-1レベルのコバルトを定量した.試料をキャリヤー(0.25M硫酸)に注入し,緩衝液(酢酸アンモニウム-クエン酸二アンモニウム)の流れと合流させた後,発色試薬{1.0%(w/v)ニトロソR塩}を注入して,コバルト-ニトロソR錯体を形成させる.最終的に干渉除去剤{2M硫酸-1%(v/v)H2O2}の流れと合流させた後,分光光度計に導入して吸光度(480nm)を測定し,コバルトを定量する.ポンプ流量の変動,及び分光光度計の変動を補正するために試料測定前に発色試薬のみを系内に注入して,試薬から試験値吸光度を測定してシステムの補正を行う.本システムの分析速度は6試料/時であり,測定精度RSDは8.0%(0.5μg ml-1レベル,n=3)である.