ポリテトラフルオロエチレン製メンブランフィルター捕集-チオシアン酸鉄錯イオン発色による非イオン界面活性剤の定量(<特集>若手研究者の初論文特集)

概要

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We reported on a spectrophotometric method for the determination of polyoxyethylene nonionic surfactants(NS) using a polytetrafluoroethylene(PTFE) membrane filter in a previous paper. The method is based on the collection of NS on the filter, and the formation of an NS-iron(III)-thiocyanate complex. Although it is a simple and rapid method, it is not good regarding the precision of repeated blank tests, because of the instability of a mixed solution of potassium thiocyanate and iron(III) chloride. In the present work, the concentration of the potassium thiocyanate and iron(III) chloride solution was studied in detail to improve the precision of repeated blank tests. The improved procedure was as follows. After a 100 ml sample solution (0〜120μg heptaoxyethylenedodecylether) was filtered through a PTFE filter (pore size: 0.1μm, Φ: 25mm), 2 ml of a potassium thiocyanate solution(6 M) and 2 ml of an iron(III) chloride solution (8 mM) were added on the filter, respectively. NS associated with iron(III)-thiocyanate was eluted with 5 ml of methanol, and the absorbance of the solution was measured at 510 nm. The precision of repeated tests (n=3) was ca.2% on both the blank and the sample.
2004-09-05