Gas chromatographic determination of nitrite in foods as trimethylsilyl derivative of 1 H-benzotriazole

Abstract

1,2-Diaminobenzene reacts with nitrite in acidic solution to form 1 H-benzotriazole, which can be extracted into ethyl acetate. After evaporation of the ethyl acetate, 1 H-benzotriazole is determined as its trimethylsilyl derivative by gas-liquid chromatography on a column of 15% SE-30 on Chromosorb G HP at 200°C with flame-ionization detection. The nitrite concentration is calculated from the peak height. Amounts of 0.5–10 μg of nitrite-nitrogen can be determined. For the determination of nitrite in foods, clean-up of the crude extracts by ion-exchange column chromatography allows the satisfactory elimination of interferents and permits concentrations down to 0.41 ppm to be determined. The recovery of nitrite added to foods at the 4.1 ppm level ranges from 94.6 to 98.7% and at the 8.2 ppm level it ranges from 95.2 to 98.8%. The trimethylsilyl derivative of 1 H-benzotriazole was identified as 1-trimethylsilylbenzotriazole by combined gas chromatographic-mass spectrometric examination and nuclear magnetic resonance spectrometry.