COMPARISON OF DIFFERENT METHODS FOR DETERMINATION OF SODIUM CHLORIDE IN CHEESE

The content of NaCl (weight fraction of Cl– ions, in %) wasanalysed in different cheeses, which were bought in supermarkets, and made bydomestic manufacturers. Sodium chloride in cheese samples was analysed after theextraction of chloride by nitric acid solution. Concentration of chloride ions waspotentiometricly determined, with the chloride selective electrode and titrimetriclyby Volhard method. According to the results in the analysis of the content of NaClin %, by different methods it was determined that the share of NaCl in % rangedfrom 0.66 to 4.43% (determined by potentiometric route) that is from 0.97 to4.72% (determined by titrimetric route by Volhard method). The difference inreceived results in different methods is less if the share of NaCl, in % is higher than3%. If the share is less than 3%, the difference in results rapidly increases, and thebiggest difference is when the share is less than 1%. This analysis was doneaccording to the results received by Volhard method, which is accepted as astandard method. As Volhard method is in connection with cheese resolving byintense oxidation means, azotic acid and potassium permanganate, obligatory infume board (hood), it is not a practical method. On the other hand, thepotentiometric method with usage of the chloride-selective electrode is very simpleand gives reliable and reproductive results. In case of a small content of NaCl, in %, higher precision and accuracy of determination by chloride-selectiveelectrode can be obtained by indirect measurement of chloride-ions (by standardaddition method).