Determination of Chloride in Polyvinyl Chloride by FAAS and Turbidimetry

The polyvinyl chloride sample was carbonized by heating in porcelain crucible using anhydrous sodium carbonate as fixative,and finally ignited at 700℃for 2 h in muffle furnace.The residue was taken up with water.An aliquot of the sample solution was taken for the determination of chloride either by FAAS or by turbidimetry.In FAAS determination,a definite and excess amount of Ag~+-standard solution was added to precipitate Cl~- as AgC1,and the Cl~- content was determined indirectly by determining the excess amount of Ag~+- ion.In turbidimetry,AgC1 was suspended by adding silver nitrate solution to the sample solution in dilute HNO_3 medium and its apparent absorbance was measured with an absorption cell of 1 cm at the wavelength of 360 nm. Linearity ranges were found in 0 to 140μmol·L~(-1)of solution for FAAS,and in 0.4—4.8 mg·L~(-1)for turbidimetry.Values of RSD's(n=6)found for both methods were≤1.9%.Values of recovery found were in the range 95.0%—102.5%.Relative deviation of the results between the two methods was less than±1.1%.