火焰原子吸收光谱法及比浊法测定聚氯乙烯中氯
Determination of Chloride in Polyvinyl Chloride by FAAS and Turbidimetry
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摘要: 以无水碳酸钠为灰化固定剂,于瓷坩埚中加热将试样灰化,于高温炉中在700 ℃燃烧2 h,用水溶出残渣,分取部分试液用火焰原子吸收光谱法(FAAS)或浊度法测定其中氯离子.加入过量银以沉淀样品溶液中的氯离子,用FAAS法测定银以间接测定氯,或通过测定氯化银悬浮体的表观吸光度而测定氯,建立了FAAS法及比浊法测定聚氯乙烯中氯含量的方法.线性范围:FAAS法为0~140 μmol·L-1,比浊法为0.4~4.8 mg·L-1.测定结果的相对标准偏差≤1.9%,加标回收率95.0%~102.5%.两种方法测定结果的相对误差小于±1.1%.Abstract: 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 AgCl,and the Cl- content was determined indirectly by determining the excess amount of Ag+-ion.In turbidimetry,AgCl was suspended by adding silver nitrate solution to the sample solution in dilute HNO3 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 140 μmol·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%.