Determination of nitrite by gas-chromatography

Abstract

ο-Phenylenediamine reacts with nitrite to form 1H-benzotriazole which can be extracted into MIBK.By means of injection of this MIBK layer into gas-chromatograph equipped with a thermal conductivity detector, the nitrite is determined from the peak height. Though the sensitivity is low compared with the colorimetric method, the gas-chromatographic method is superior in the specificity.
Put 20 ml of the sample solution and 3 ml of 1 N hydrochloric acid into a 100-ml separatory funnel, and then, add 2 ml of 0.0187 M ο-phenylenediamine solution. After standing for 20 min, 5 ml of 1 M sodium acetate is added and 11 g of sodium chloride is added. Then, the 1H-benzotriazole formed is extracted into 1 ml of MIBK by shaking for 10 min andthe MIBK extract is dried with 0.5 g of molecular sieves 3 A. Five micro liters of the MIBK extract isinjected into the gas-chromatograph and the peak height is measured. The nitrite content is calculated by using a calibration curve which has been drawnpreviously by experiments with known amounts of nitrite.