The Analysis of Phosphate, Arsenate, and Silicate by Reverse Phase Liquid Chromatography

Abstract

Abstract The separation of 12-Molybdoarsenic Acid (12-MAA), 12-molybdosaicic Acid (12-MSA) and 12-molybdophosphoric Acid (12-MPA) by a disposable commercially available SEP-PAK(tm) C18 reverse phase liquid chromatography column is described with UV-visible detection. The mobile phase is an acetonitrile-water solution which is 0.050 F in HCIO4 and 0.016 F in MoO4 −2. In these solutions lowering the acetonitrile concentration to 10.0% (v/v) inhibits the formation of 12-MAA while allowing the formation of 12-MPA and 12-MSA resulting in the retention of 12-MPA and 12-MSA upon infusion through a SEP-PAK C18 column. The arsenate anion remains in the column effluent. 12-MSA is eluted from the column by 3.0 ml of a solution which is 25.0% in acetonitrile, 0.060 F in HClO4 and 0.016 F in MoO4 −2 and the 12-MPA is eluted from the column by 3.0 ml of a solution which is 55.0% (v/v) in acetonitrile, 0.060 F in HCIO4 and 0.016 F in MoO4 −2. The column effluent which contains AsO4 −3 is then brought up to 35.0% acetoni...