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

Mohau N Moshoeshoe,Veronica Obuseng

doi:10.17159/0379-4350/2018/v71a10

Mohau N Moshoeshoe, Veronica Obuseng

Open Access

https://doi.org/10.17159/0379-4350/2018/v71a10

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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 NO 2 – , NO 3 – and PO 4 3– in water samples. The treatment plant was found to be functioning within expectations, removing 97.6% NO 2 – , 88.0% NO 3 – and 90.9% PO 4 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

Highlights

Nitrogen is a vital nutrient for both plants and animals[1]. It exists as nitric oxide (NO), nitrite (NO2–) and nitrate (NO3–)
A Dionex, seven-anion standard mixture, which contains a mixture of F– (20 ppm), Cl– (100 ppm), NO2– (100 ppm), Br– (100 ppm), NO3– (100 ppm), PO43– (200 ppm) and SO42– (100 ppm) was used to prepare calibration mixtures for nitrate, nitrite and phosphate within a working range of 1 to 100 ppm in DDW
The use of high-performance liquid chromatography (HPLC) technique in this study demonstrated its benefit of being able to carry out a simultaneous determination of NO2, NO3– and PO43– in water samples

Summary

Introduction

Nitrogen is a vital nutrient for both plants and animals[1]. In the environment, it exists as nitric oxide (NO), nitrite (NO2–) and nitrate (NO3–). It exists as nitric oxide (NO), nitrite (NO2–) and nitrate (NO3–) These are ever-present in everyday samples such as environmental, food and biological samples.[2] In water, NO3– occurs both naturally and through external inputs which may include run-off from agricultural soils, soil organic matter as well as livestock and human faecal material.[3] Contamination of groundwater resources by nitrate is mainly a consequence of anthropogenic activities and uncontrolled discharges from industries, agricultural activities, sewage treatment plants and pit latrines.[4]. Excess nitrates and nitrites lead to algal blooms, resulting in lowered levels of oxygen in the water, leading to eutrophication.[7]

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