Simultaneous determination of nitrate, nitrite and phosphate in environmental samples by high performance liquid chromatography with UV detection

Abstract

An HPLC method using anUVdetector was developed for the simultaneous determination of nitrites, nitrates and phosphates in environmental samples. Chromatographic separation was achieved isocratically on a Phenomenex Synergi Polar-RP LC column using acetonitrile and acidified water (pH 2.7) at 60:40 v/v as mobile phase. Baseline resolution of all the three analytes was achieved within 3 min. The developed method was applied to water samples obtained from the wastewater treatment plant in Gaborone, Botswana. The use ofHPLC technique in this study demonstrated its ability to carry out a simultaneous determination of NO₂^–, NO₃^– and PO₄^3– in water samples. The treatment plant was found to be functioning within expectations, removing 97.6% NO₂^–, 88.0% NO₃^– and 90.9% PO₄^3– from the received wastewater.Results of the developed method were comparable with those of the traditional ion chromatography method, showing accuracy values between 95.22%and 98.04 %. The precision of the method for the determination of all analytes was determined by RSD values, all of which were lower than 5%. The method is of low cost, fast, has an easy procedure and avoids the use of many reagents – some of which may be hazardous.

Keywords: HPLC-UV, simultaneous determination, nitrate, nitrite, phosphate