Metrohm has developed a direct injection ion chromatography method for the determination of low levels of anions in a nitrate matrix
Trace anions in nitric acid - column temperature improves the separation.
Separation on the high-capacity Metrosep A Supp 16-250 was achieved by optimising both eluent composition and column temperature.
An eluent composition of 3mmol/L Na2CO3 and 25mmol/L NaOH and a column temperature of 25C yielded an excellent chromatographic separation with nitrate eluting as the last anion.
Calibration curves were linear with a coefficient of determination of 0.9994 or better.
Spike recovery percentages for chloride and sulfate in a diluted nitric acid matrix (1:100, w/w) were within 95-102% and 95-106%, respectively.
The direct injection arrangement requires no neutralization of the acid and is highly suitable for accurately determining low levels (ppm) of chloride and sulphate in the presence of high quantities of nitrate (percent range).
