Simultaneous determination of nitrate and nitrite by GC/MS

We devised a sensitive and simple method to determine nitrate and nitrite simultaneously by an extractive alkylation technique and gas chromatography/mass spectrometry. Nitrate and nitrite were alkylated with pentafluorobenzylbromide, with tetradecyldimethylbenzylammonium chloride as the counter-ion in an alkaline solution. The alkylated nitrate and nitrite were analyzed by gas chromatography/mass spectrometry using the negative-ion CI mode. The lower limits of detection of nitrate and nitrite were 0.005 μmol/ml. The calibration curves of nitrate and nitrite were linear in the concentration range from 0.01 to 1.00 μmol/ml. This method should be useful to determine these compounds in criminal cases.