Determination of azide, iodide, nitrite, nitrate, cyanide and thiocyanate by GC/MS

We devised a sensitive and simple method to determine azide, iodide, nitrite, nitrate, cyanide and thiocyanate, using an extractive alkylation technique and gas chromatography/mass spectrometry (GC/MS). Nitrate was reduced to nitrite by hydrazine sulfate prior to alkylation. Their anions were alkylated with pentafluorobenzylbromide, with tetradecyldimethylbenzyl-ammonium chloride as the counter-ion in an alkaline solution. GC/MS was carried out in the positive ion electron ionization (EI) mode and the negative ion chemical ionization (CI) mode with isobutane as reagent gas. The calibration curves were liner by the CI mode in the concentration range from 0.01 to 1.00 μmol/ml.