酸水解-离子色谱法测定精四氯化钛中三氯乙酰氯

Determination of Trichloroacetyl Chloride in Refine Titanium Tetrachloride by Acid Hydrolysis and Ion Chromatography

建立了酸水解-离子色谱法测定精四氯化钛中痕量三氯乙酰氯（CCl3COCl）的方法。四氯化钛样品与2 mol/L HCl按体积比1∶4水解平衡后,采用氢氧化物共沉淀法去除溶液中Ti4＋,V5＋和Fe3＋等金属离子,用Ag2O沉淀法降低水解溶液中Cl-浓度,水解溶液通过H型阳离子交换柱和水系滤膜,离子色谱法测定溶液中三氯乙酸（TCAA）,据TCAA与CCl3COCl摩尔量守恒计算样品中CCl3COCl含量。结果表明,共沉淀溶液p H值在9.0~10.0范围内,可将目标金属离子基本去除完全;加入Ag2O降低溶液Cl-浓度后,溶液中Cl-,NO-3和SO2-4的浓度对水解溶液中TCAA的色谱法峰无影响。本方法对精四氯化钛样品中CCl3COCl的定量限为1.20μg/g,低于俄罗斯精四氯化钛中CCl3COCl允许限值（5μg/g）;方法加标回收率在84.1%~87.3%之间,共沉淀时溶液p H值的轻微变化对回收率无明显影响,分析结果稳定可靠;方法用于5个平行样品中CCl3COCl含量测定（45.6,37.9,40.8,38.9和43.5μg/g）,相对标准偏差7.7%,方法精密度较好。方法满足精四氯化钛中CCl3COCl质量控制要求。

A method was proposed for the determination of trichloroacetyl chloride （CC13COC1） in refined titanium tetrachloride （TiC14 ） by ion chromatography after acid hydrolysis. Acid hydrolysis reaction was carried out according to the volume ratio （1：4, V/V） of TiC14 samples to HCI solution （2 mol/L HC1）. NaOH and Ag20 were added to hydrolysis solutions in sequence to remove and reduce metal cations （ e. g. Ti4＋, V5＋, Fe3＋） and CI-, and then hydrolysis solutions was purified by H-type cation exchange column. Trichloroacetate （TCAA） was determined in the treated solutions after membrane filtration, and CCI3 COC1 concentration was calculated according to molar amount conservation. Results showed that almost all of the target metal cations were removed in range of pH 9. 0 - 10. 0 of hydroxide co-precipitation solutions, and the residual concentrations of CI-, N03 and SO42- in solutions had no influence on the determination of TCAA after removal of C1-. Quantitation limit of the method （MQL） for CCI3COC1 in refine TiCl4 samples was 2. 1 mg/L （1.2 μg/g）, which was lower than the standard limit of refine TiC14 of Russia （5 μg/g）. The recoveries of CC13COC1 added to high pure TIC14 were in the range of 84. 1% -87.3%, and the analytical results of 5 replicates of refined TIC14, sample were 45.6, 37.9, 40.8, 38.9 and 43.5 μg/g with RSD of 7.7%. The method showed better reliability, stability and precision, which satisfied the requirement of quality control for CC13COC1 in refined titanium tetrachloride.