IC Determination of Nitrite and Nitrate in Soil with Solid Phase Extraction

Contents of NO2- and NO3- in soil were determined by ion chromatography (IC). The sample was extracted ultrasonically with water and purified by passing through OnGuardⅡP and OnGuardⅡRP solid phase extraction columns. The 2 anions in the extract were separated on AS11-HC column with AG11 as guard column, by elution with 15 mmol·L-1 KOH solution as mobile phase and detected by inhibitory conductivity detection. Linear relationships between values of peak area and mass concentration of NO2- and NO3- were kept in ranges of 0.01-1.00 mg·L-1and 0.10-10.0 mg·L-1 respectively. Values of detection limit (3s/k) found were 0.16 μg·g-1(for NO2-) and 0.24 μg·g-1 (for NO3-). Tests for recovery and precision were made, giving values of recovery and RSD′s (n=7) in the ranges of 85.0%-100% and 2.9%-4.1% for NO2-, 93.5%-106% and 2.2%-3.4% for NO3- respectively.