Determination of trace amounts of nitrate in potassium chloride-extracts by HPLC with ultra-violet-detection

A method is presented that allows the determination of trace amounts of nitrate in I M potassium chloride extracts of environmental soil samples from Northern Europe. To avoid the interference of bromine ions on the evaluation of the nitrate peak, 50 muL of a 50mg/L nitrate standard solution are added to a 5mL soil extract. This makes sure that the overall nitrate concentration in the spike is >500 mug/L which allows an exact and reliable determination of the nitrate concentration. Analyses of the soil extracts are carried out by anion-exchange HPLC with ultra-violet detection at lambda = 210nm using 0.1 M KCl as eluent. Concentrations down to 25 mug/L of nitrate can be analyzed