SEPARATION OF OXYANIONS OF PHOSPHORUS BY SINGLE COLUMN ION CHROMATOGRAPHY

Separation of mixtures containing hypophosphite, phosphite, orthophosp hate, chloride, nitrate and sulphate ions has been achieved using a Vy dac 300 IC 405 column, refractive index detection and eluents which we re 2mM in p-hydroxy benzoic acid or 4mM in p-amino benzoic acid (adjus ted to pH 5.5). Calibration curves were linear over the concentration range 3 to 30 mg P/l.; and the precision (RSD for peak heights in mixt ures) was < +/-10%. Using p-hydroxy benzoic acid, detection of eluted peaks by indirect UV absorption was equally satisfactory. In an initia l survey, the elution behaviour of nine oxyanions of phosphorus (simpl e ions and condensed species) was examined, using eluents containing d ifferent organic carboxylic acids (six aliphatic and nine aromatic), p resent at levels of 1 to 5mM; with the pH adjusted to values between 3 and 8.6. No suitable conditions for separating mixtures containing co ndensed phosphates were identified.