Determination of anions in atmospheric precipitation by ion chromatography

Abstract

The semi-automated ion-chromatographic system studied permitted analyses of 60 samples per day for the three major anions found in atmospheric precipitation, viz., sulphate (0.06–10.0 mg l^–1), nitrate (0.022–2.00 mg l^–1 as nitrogen) and chloride (0.028–1.50 mg l^–1). The sensitivity was too low to determine nitrite, orthophosphate, bromide and sulphite under the selected operating conditions; however, the expected concentrations of these species were less than 0.1 mg l^–1. Fixed point calibrations were invalid as calibrations were non-linear. When the subject system was compared with alternative procedures, the resultant data for sulphate, nitrate and chloride agreed to within 2%. Ion-chromatographic data for fluoride were unacceptable, as shown by the inter-comparison with two reference procedures.