STUDIES ON THE PREPARATION OF SAMPLE SOLU TION FOR COLORIMETRIC DETERMINATION OF NITRITE IN FOODS

The preparation of a sample solution for the colorimetric determinatio n oi nitrite in processed foods has been studied in detail focusing on the deproteinizing procedure. A simple and rapid deproteinizing proce dure was obtained by precipitation of colloid zinc hydroxide which was formed by adding constant amounts of zinc acetate and sodium hydroxid e to the alkaline extracts from salted salmon roe, The amounts of nitr ite isolated from the samples of salted roe of salmon, pollack, sausag e and ham fortified at 5, 50 or 70 mu g/g of nitrite were determined u sing this procedure and the recoveries of nitrite were found to be not less than 84.8%. This preparation of sample solution is applied for t he determination of residual nitrite in various foods by diazotaiztion -coupling colorimetry.