Dual flow-injection analysis system for determining bromide and reactive phosphorus in natural waters

Abstract

An inexpensive, dual flow-injection instrument for simultaneously determining low concentrations of both bromide and dissolved reactive phosphorus in natural waters is reported. An in-line C 18 resin column was needed to remove interference in the bromide determination from dissolved organic matter present in most natural waters. The bromide method had a detection limit of 4 υg Br 1 −1 and was linear over the range 0–2 mg Br 1 −1 with good precision [C.V. 5.3% at 0.1 mg Br 1 −1 ( n = 10) and 0.5% at 2.0 mg Br 1 −1 ( n = 10)]. The dissolved reactive phosphorus method had a detection limit of 0.6 υg P 1 −1 and was linear over the range 0–50 υg P 1 −1 with good precision [C.V. 2.9% at 2.0 υg P −1 ( n = 3) and 0.5% at 50 υg P 1 −1 ( n = 3)]. The dual method can analyse 30 samples per hour when analysing P and Br sequentially (35 samples per hour in simultaneous analysis mode) and has been used in field experiments to determine the spiralling of phosphorus in Myrtle Creek, Australia.