Sequential potentiometric determination of chloride and nitrate in meat products

The analytical control of chloride and nitrate in meat products is important. For this reason in this work a sequential method for their determination by using chloride- and nitrate-selective electrodes has been developed. The extraction of both ions was carried out by stirring the samples for 30 min in a hot 50 x 10(-2) mol litre(-1) sulphuric acid solution. Direct potentiometry for chloride and multiple standard additions for nitrate were used as analytical techniques of measurement. The mean coefficient of variation and the average percentage of spike recoveries calculated for the chloride determination in five different meat products were 0.68% and 101%, respectively. For the nitrate determination these data were 0.84% and 101%, respectively. The limits of detection were 71.0 mg kg(-1) and 23.2 mg kg(-1) for chloride and nitrate, respectively. The mean chloride and nitrate concentrations determined by application of the developed method to 50 samples of meat products were found to be 21.1 g kg(-1) and 133.5 mg kg(-1), respectively. Throughout the study, the Volhard titration for determination of chloride and the brucine spectrophotometric method for determination of nitrate, adopted as reference methods, were used simultaneously. Comparison of variances and linear regression analysis of the results obtained were carried out to validate the proposed sequential potentiometric method. (C) 1997 Elsevier Science Ltd.