Measurement of Sulfide in Real Samples by Vortex-Assisted Liquid-Liquid Microextraction Method with Detection of UV-Vis Spectrophotometry

In this study, a vortex-liquid liquid micro-extraction method for concentrating low amounts of sulfide before measuring it with an ultraviolet-visible spectrophotometer is introduced. This method is based on the formation of methylene blue complex for selective and sensitive detection of sulfide ions. The procedure was to form a sulfide with N, N-dimethyl-p-phenylenediamine (DMPPDA) ligand in the presence of ferric chloride to produce methylene blue, a dye that was extracted into 1,2 dichloroethane organic solvent and measured at a maximum wavelength of 658 nm by an ultraviolet-visible spectrophotometer. The effect of effective parameters on the extraction of methylene blue complex including the type of extraction solvent, organic solvent volume, concentration of dimethyl-p-phenylenediamine (as a ligand), vortex time and speed of vortex agitator were investigated and optimized. Under optimal conditions, the proposed method was able to successfully detect sulfide ions in the range of 0.05 to 0.5 ng / ml. The detection limit obtained for sulfide in 3 sample measurements of the control sample was 0.018 ng / ml. In addition, the relative standard deviation for 5 measurements of the 0.05 ng / ml sulfide sample was 2.8%. The effect of several potentially disturbing ions was also investigated. This method was successfully used to determine the amount of sulfide in 3 water samples (tap water, groundwater and waste water).