色素法による2-(1-ピペリジノ)エチルベンチレートエチルブロミドの比色定量法

概要

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A colorimetric method for the determination of 2-(1-piperidino)ethylbenzilate ethylbromide (I) based on its association with an organic dye has been established. Dyes which have optimum pH in the weakly acidic range are used in the phosphate-buffered solution. The procedure is as follows. Twently milliliters of ethylenedichloride is put into a 40 ml glass-stoppered centrifuge tube. Four milliters of M/15 phosphate buffer solution of pH 6.4 (or of 5.0 in case of Iodophenol Blue), 2 ml of 0.1% Bromocresol Purple solution (or 0.1% Iodophenol Blue solution) and 2 ml of the sample solution containing 20140 μg of (I) are added. After the mechanical shaking for 10 min. and separation of layers by centrifuge, the water layer is discarded. A 10 ml aliquot of ethylenedichloride layer is transfered into another 40 ml centrifuge tube, and 10 ml of 0.1M sodium carbonate solution is added. After shaking for 2 min. and separation by centrifuge, the absorbance of the water layer is measured at 591 mμ (598 mμ in case of Iodophenol Blue solution) against a blank.