The alternative use of layered double hydroxides as extraction medium coupled with microcomplexation for determination of phosphate in water samples.

A simple, rapid, in situ, and green extraction combined with a microcomplexation has been developed for the spectrophotometric determination of phosphate in water samples. Through their formation, layered double hydroxides (LDHs) were employed as the extraction medium, instantly commenced by a rapid addition of a mixed solution of Mg2+ and Al3+ ions into alkaline phosphate solution. After the extraction, LDH precipitate containing phosphate was dissolved by sulfuric acid and the released phosphate was subsequently detected via its complexation with molybdate in the presence of antimonyl and ascorbic acid. Under optimum conditions, the linearity in the range of 5-200μgL-1, with the correlation coefficient (r2) of 0.9969, and the enrichment factor (EF) of 14 were obtained. The limit of detection (LOD) of 5μgL-1 and good precision, with the relative standard deviations (RSDs) less than 8.16%, were achieved. The proposed method was successfully applied to determine phosphate in water samples and the relative recoveries of 72.97-115.32% were obtained.