Determination of Nitrite-Nitrogen, Ammonia-Nitrogen and Nitrate-Nitrogen in Soil and Sediment by Gas- Phase Molecular Absorption Spectrometry

A method for the determination of nitrite-nitrogen, ammonia-nitrogen and nitrate-nitrogen in soil and sediment by gas-phase molecular absorption spectrometry was established. Based on the extraction method in HJ 634-2012, 3 nitrogent forms were extracted from soil and sediment samples with potassium chloride solution at (20±2)℃. After centrifugation, the contents of nitrite-nitrogen, ammonia-nitrogen and nitrate-nitrogen in the supernatant were determined by gas-phase molecular absorption spectrometry. The results showed that linear relationships between mass concentrations of nitrite-nitrogen, ammonia-nitrogen and nitrate-nitrogen and their absorbances were kept in the same range of 0.05-2.00 mg·L^-1, and detection limits (3.143s) were 0.02, 0.08, 0.02 mg·kg^-1, respectively, lower than those given by HJ 634-2012. Recoveries from the spiked recovery test were in the range of 81.1%-96.2%, 81.9%-88.1% and 86.0%-105%, respectively, with RSDs (n=6) of the determined values within 15%. Tests for method comparison between the proposed method and HJ 634-2012 were made, results of tests for recovery and precision of the 2 methods were basically the same, and there was no significant difference between the 2 methods by results of two-sideds F test and t test .