Sequential flow injection voltammetric determination of phosphate and nitrite by injection of reagents into a sample stream

Abstract

For the intermittent analysis of large-volume water samples, such as a hydroponic fluid, a modified use of flow injection analysis is proposed. In this modification the water sample is made the eluent in the flow injection system and reagents for the determination of individual components are injected into the sample stream sequentially. As an illustration of this principle a sample solution containing phosphate and nitrite has been analysed in this way using acidic molybdate and acidic bromide reagents to determine phosphate and nitrite voltammetrically at a glassy carbon electrode. Phosphate was determined at the 0.5–50 × 10^–5M level and nitrite at the 0.5–5 × 10^–4M level without mutual interference and with good precision.