Determination of nitrate and nitrite by continuous liquid-liquid extraction with a flow-injection atomic-absorption detection system

Abstract

A flow injection system coupled on-line with a continuous liquid-liquid extractor is used for the indirect determination of nitrate and nitrite with an atomic-absorption detection system. These anions form ion-pairs with the copper(I)-neocuproine chelate which are extracted into methyl-isobutyl-ketone, the atomic-absorption signal of copper from the organic phase being proportional to the nitrate or nitrite concentration. The methods proposed herein are suitable for determining nitrate or nitrite at the βg ml−1 level with a sampling frequency of 35 ± 5 h−1. The methods compare favourably with their batch counterparts with regard to sensitivity, selectivity, sample volume and sampling frequency.