Spectrophotometric Determination of Trace Amount of Sulfide by Formation of Iodide and Its Solvent Extraction with Mehtylene Green

요오드이온 생성 및 Methylene Green과의 용매추출에 의한 미량 황이온의 분광광도법 정량

The iodide formed stoichiometrically for sulfide by its oxidation with iodate was extracted as an ion-pair with methylene green into 1,2-dichloroethane and the extract was measured spectrophotometrically at 656nm for the determination of sulfide. Hydrogen sulfide separated from the sample matrix was introduced into a solution containing pH 3.5 acetate buffer and iodate, in which the hydrogen sulfide was completely converted into iodide. A linear calibration graph was obtained over the range $3{\times}10^{-7}{\sim}1.2{\times}10^{-5}M$ sulfide($0.0096{\sim}0.384{\mu}g$ of $S^{2-}/ml$) and the detection limit was $0.0032{\mu}g/ml$. The apparent molar absorptivity and a correlation coefficient(r) were $6.7{\times}10^4L\;mole^{-1}\;cm^{-1}$ and 0.999, respectively. When applied to the stream water samples, the proposed method gave a relative standard deviation of 1.59% at $5{\times}10^{-6}M$ sulfide level.

요오드산 이온의 황이온의 산화에 의해 화학양론적으로 형성되는 요오드이온과 methylene green과의 이온쌍을 1,2-dichloroethane으로 추출하여 656nm에서 분광광도법에 의해 황이온의 정량법을 확립하였다. 시료기질로부터 분리되어지는 황화수소는 pH 3.5 초산 완충용액과 요오드산 이온이 포함된 용액에 도입되어 완전히 전환되었다. 황이온의 정량범위는 $3{\times}10^{-7}{\sim}1.2{\times}10^{-5}M$ ($0.0096{\sim}0.384{\mu}g/ml$) 였으며, 검출한계는 $0.0032{\mu}g/ml$였고, 몰흡광계수는 $6.7{\times}10^4L\;mole^{-1}\;cm^{-1}$였다. 본 정량법을 하천수 중에 응용하였을 때 $5{\times}10^{-6}M$ 농도에서 상대표준편차는 1.59%로 미량에서 공존이온의 영향을 거의 받지 않고 재현성 있는 결과를 나타내므로 실시료 중에 효과적으로 응용할 수 있으리라 생각된다.