Spectrofluorimetric determination of indoxyl sulfate in human plasma after salting-out assisted liquid-liquid extraction

A simple analytical method was developed to quantify indoxyl sulfate (InS) in plasma using a salting-out assisted liquid-liquid extraction and spectrofluorimetry. Plasma samples were deproteinized by acetonitrile. Then, sodium chloride solution was added to separate acetonitrile and aqueous phase. The fluorescence intensity of InS which extracted to acetonitrile phase was determined by spectrofluorimetry. The method of presentation has a linear range between 2.5 and 40 mu g/ml with a coefficient of determination (R-2) of 0.995. Accuracy (% error) and precision (relative standard deviation) were 15% at nominal concentration and less than 15% at all levels, respectively. This established analytical method, which is sensitive and reproducible, could be applied for the quantification of InS in real plasma samples.