SPECTROPHOTOMETRIC DETERMINATION OF CHLORIDE IN BARIUM-SULFATE PRECIPITATES FOLLOWING ISOLATION OF THE ANALYTE

A spectrophotometric method was developed for the determination of chl oride concentrations between 0.2 and 5 mgL-1 in barium sulphate precip itates, obtained by precipitation of sulphate in concentrations of 50 to 250 mgL-1 or even lower. The proposed method involves prior dissolu tion of the barium sulphate precipitate in hot conc. sulphuric acid an d collection of the released hydrogen chloride by means of gaseous nit rogen. The analytical calibration function was obtained by the least-s quares procedure from 10 determinations at each of three concentration levels of a standard solution of chloride. The lack of fit of experim ental points to the least-squares straight line was found to be neglig ible at a significance level of 5%. Blank measurements were required i n all instances as the blank absorbance varied with time.