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

A method was proposed for the determination of trichloroacetyl chloride (CCl3COCl) in refined titanium tetrachloride (TiCl4) by ion chromatography after acid hydrolysis. Acid hydrolysis reaction was carried out according to the volume ratio (1:4, V/V) of TiCl4 samples to HCl solution (2 mol/L HCl). NaOH and Ag2O were added to hydrolysis solutions in sequence to remove and reduce metal cations (e.g. Ti4+, V5+, Fe3+) and Cl-, and then hydrolysis solutions was purified by H-type cation exchange column. Trichloroacetate (TCAA) was determined in the treated solutions after membrane filtration, and CCl3COCl 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 Cl-, NO3- and SO42- in solutions had no influence on the determination of TCAA after removal of Cl-. Quantitation limit of the method (MQL) for CCl3COCl in refine TiCl4 samples was 2.1 mg/L (1.2 mu g/g), which was lower than the standard limit of refine TiCl4 of Russia (5 mu g/g). The recoveries of CCl3COCl added to high pure TiCl4 were in the range of 84.1%-87.3%, and the analytical results of 5 replicates of refined TiCl4 sample were 45.6, 37.9, 40.8, 38.9 and 43.5 mu g/g with RSD of 7.7%. The method showed better reliability, stability and precision, which satisfied the requirement of quality control for CCl3COCl in refined titanium tetrachloride.