Water‐in‐oil microemulsion as mobile phase in thin‐layer chromatographic retention studies of anions

A water‐in‐oil (W/O) microemulsion, consisting of sodium dodecyl sulphate (SDS)/1‐pentanol/water/heptane, has been used as mobile phase for the separation of inorganic anions from their binary mixtures, for example, IO 4 − ‐NO 2 − , IO 4 − ‐BrO 3 − , IO 4 − ‐I − , MnO 4 − ‐BrO 3 − , MnO 4 − ‐NO 2 − , and MnO 4 − ‐Br − . The weight ratio, SDS/ n ‐pentanol was kept constant at 1/2.46 for all compositions. The retention efficiency of anions on layers of silica gel G, alumina, microcrystalline cellulose, kieselguhr G, and mixtures of kieselguhr and cellulose in 4:1 and 3:2 ratios has been examined with the W/O microemulsion system as a mobile phase. Thin layers of kieselguhr were most useful for differential migration of anions. Quantitative separation of IO 4 − from accompanying ions, limits of identification, and dilution of few anions are reported. The effects of amines, phenols, and heavy metals on the separation efficacy of IO 4 − also have been investigated.