Determination of Total Phosphorus in Water Sample by Digital Imaging Colorimetry

In acidic medium, the interaction of potassium dihydrogen phosphate with ammonium molybdate, potassium antimonyl tartrate, and ascorbic acid result in a blue compound complex. With increasing potassium dihydrogen phosphate concentration, the color of the solution and the RGB value of digital imaging are increased. Thus a novel assay of total phosphorus based on digital imaging colorimetry (DIC) has been developed. By comparing the DIC and the ammonium molybdate spectrophotometric method, including factors on digital imaging and optimal conditions of same interacting system were discussed. The present novel assay is very simple and sensitive. Water samples were analyzed with the relative standard deviation (RSD) of 1.8%–3.4% and the recovery of 99.7%–102.5%. The results of determinations for water samples are consistent with those obtained using the spectrophotometric method.