Shiro Matsuoka

Flow analysis of micro amounts of chromium(III) and (VI) in natural water by solid phase spectrophotometry using diphenylcarbazide

Specific determination of chromium(III) and chromium(VI) in natural water samples was performed without mutual separation. The chromium in sample solution was concentrated on cation-exchange resin packed in a flow-through cell as a reaction product of chromium(VI) with diphenylcarbazide. The absorbance increase caused by the accumulation of the complex on cation-exchange resin was continuously measured. By using peroxodisulfate as an oxidizing agent, the chromium(III) in sample solution was completely oxidized to chromium(VI). The chromium(III) concentration was calculated by the difference between the values of the total chromium and chromium(VI). The detection limit for chromium(VI) and total chromium was 70 pg and 120 pg, respectively. This method was applied to the specific determination of chromium in several natural water samples. The results of the total chromium obtained by the proposed method show moderate agreement with that obtained with ICP-MS. Unlike the previous results reported in chromium speciation studies, the predominant chromium species in natural water was chromium(VI).

Cavernous hemangioma in the pineal region

A cavernous hemangioma in the pineal region of a 22-year-old man is reported. Because the patient had diabetes insipidus and a contrast-medium-enhanced mass in his pineal region on computed tomography, a germinoma was suspected. A ventricular shunt was made and the tumor was irradiated, but without a response. After irradiation the tumor was entirely removed, and postoperatively the diabetes insipidus improved.

Simultaneous determination of traces of heavy metals by solid-phase spectrophotometry

A coupling sensitive solid phase spectrophotometric (SPS) procedure for determination of traces of heavy metals (Me-SPS) and multicomponent analysis by multiple linear regressions (MA), a simple methodology for simultaneous determination of metals in mixtures was inaugurated. The Me-SPS procedure is based on sorption of heavy metals on PAN-resin and direct absorbance measurements of colour product Me-PAN sorbed on a solid carrier in a 1-mm cell. This methodology (Me-SPS-MA) was checked by simultaneous determination of metals in synthetic mixtures with different compositions and contents of metals important in pharmaceutical practice: Zn, Pb, Cd, Cu, Co, and Ni. Good agreement between experimental and theoretical amounts of heavy metals is obtained from the recovery test (78.3-110.0%). The proposed method enables determination of particular metal ion at the ng mL(-1) level and it was successfully applied to the determination impurities from heavy metal traces in pharmaceutical substances (Cu in ascorbic acid, Pb in glucose, and Zn in insulin). The proposed procedure could be possible contribution to the development of pharmacopoeial methodology for a heavy metals test.

Anion exchanger as a reaction/separation medium-absorptiometric determination of trace amounts of boron in waters by on-line complexation with chromotropic acid presorbed on the anion-exchange column.

A novel method of on-line absorptiometric determination for trace amounts of boron was developed based on the complexation with chromotropic acid presorbed on an anion-exchange column. On-line reaction and separation were achieved by controlling pH conditions in solutions to accelerate the 1:2 complex formation in the concentration process at pH 3 and to stabilize the complex in the separation process at pH 8. About 75% of the boron introduced into the stream was kinetically collected as the 1:2 complex on the column under the experimental conditions. The 1:2 complex was satisfactorily separated from excess reagent and matrix components by changing the concentration of NaClO4 in the eluent and its peak height on the chromatogram monitored at 350 nm was used for calibration. The sensitivity could be enhanced by increasing the sample amount introduced and the detection limits (3sigma) were 162 ng dm(-3) and 45 ng dm(-3) of boron, when 5.0 cm3 and 13.4 cm3 of the samples were used, respectively. The method has been successfully applied to the determination of boron in samples of river water, tap water and ion-exchanged water.

Application of ion-exchanger phase spectrofluorimetry to the determination of micro-amounts of some rare earth elements by flow analysis

The fluorescence bands originating from d→f electron transitions, which can be used to determine europium, terbium, dysprosium or samarium selectively, were enhanced only if these elements were sorbed in a weak-acid cation-exchange gel, i.e., CM-Sephadex. After a sample solution had been introduced into a fused-silica tube (1.5 mm i.d.) packed with 1 mg of CM-Sephadex, the fluorescence intensity increase, resulting from the rare earth elements sorbed in the ion-exchange gel, could be measured directly with good precision. For europium, the detection limit was 22 ng with an 8.3 cm3 sample solution. The sensitivity of the proposed method depended on the sample volume introduced. The cell could be used repeatedly after desorbing the target element with a solution of nitric acid.

Determination of molybdenum(VI) in natural water and rock by ion-exchange absorptiometry combined with flow analysis

Abstract Ion-exchange absorptiometry combined with flow analysis has been applied to the determination of trace amounts of molybdenum(VI) in natural water and rock. By using a pretreatment column packed with Sephadex G-25 gel, molybdenum(VI) in a sample solution can be sorbed selectively on the gel at pH 3.5. The molybdenum(VI) in the column was desorbed with EDTA as the molybdenum(VI)-EDTA complex, and the solution was introduced into a Tiron solution stream. The yellow complex formed between molybdenum(VI) and Tiron in the flow system was then concentrated on a QAE-Sephadex A-25 anion exchanger packed in a flow-through silica micro-cell. The attenuation of incident light by the molybdenum(VI)-Tiron complex on the anion exchanger in the cell was continuously recorded with a spectrophotometer at 410 nm. The complex on the anion exchanger was easily desorbed with sodium nitrate, so the flow-through cell could be used repeatedly. The minimum amount that could be detected corresponded to 15 ng of molybdenum(VI). Molybdenum(VI) in three or four sample solutions could be determined within 1 h.

Application of ion-exchanger phase visible light absorption to flow analysis. Determination of vanadium in natural water and rock

Abstract Ion-exchanger phase visible light absorptiometry combined with flow analysis has been developed and applied for the determination of vanadium in natural water and rock. The vanadium(IV) and vanadium(V) in the sample solution reacted with xylenol orange (XO) which was immobilized on the AG 1-X2 anion-exchanger packed in flow-through cell, and the increase in light absorption caused by the formation of the vanadium-XO complex in the resin was directly measured with a spectrophotometer at 532 nm. The interference by most of the co-existing ions can be effectively eliminated using trans -1,2-cyclohexanediamine- N , N , N ′, N ′-tetraacetic acid (CyDTA) and ammonium tartrate. The detection limit was 80 ng dm −3 with 5.0 cm 3 of sample solution. Vanadium contents in three sample solutions could be determined within 1 hour.

Flow Analysis Method for Trace Elements by Ion-Exchanger Phase Absorptiometry

The increase in attenuance of a colored species, which has been concentrated on-line onto ion exchanger packed in a flow-through cell, could be measured continuously with a spectrophotometer. The sensitivity of the present method depends both on the sample volume introduced into the flow system and the cross sectional area of the flow-through cell. It was possible to determine sample element concentration in mg/m3 or lower levels with a few cm3 of sample solution. The fundamental background and applicability to flow analysis of some trace elements are reviewed.

Application of solid-phase absorptiometry to microscopic spectroscopy.

試料溶液中の微量着色成分をイオン交換体等の固相に吸着濃縮させ,その固相減光度を直接測定する固相濃縮吸光光度法では,溶液相と固相との体積比を大きくすることが高感度化には特に有効である.この両相の体積比を大きく維持したまま,なおかつ測定に供する試料量を少なくするために,試料溶液中のイオン性着色成分を吸着濃縮させた直径約0.8mmのイオン交換樹脂粒1粒に,細い光束を入射し,透過光を高倍率の対物レンズを使用して集光,検出する顕微分光法を用いた新しい分析法の開発を行った.Fe(II)-フェナントロリン錯生成系,Cr(VI)-ジフェニルカルバジド錯生成系に適用した結果,1粒の樹脂粒に対してもベール則が成立することが確認された.又,対物レンズの焦点を樹脂粒の中心に合わせることで再現性も向上した.1cm3程度の試料溶液を用いても濃縮効率は数百倍であり,サブμgdm-3レベルの微量成分の定量が精度良く可能であった.