Abstract:

In order to inspect the process of L-threonine chloride to TCAce and its influencing factors, a novel method using methyl tertiary butyl ether (MTBE) as extractant and 1,2-dibromopropane as internal standard for the determination of the disinfection by-products trichloroacetone (TCAce) by gas chromatography mass spectrometry(GC-MS) was described．The formation process of TCAce and its influencing factors were discussed with L- threonine as the precursor during the chloramination process．It was indicated from the formation process that the TCAce amount produced increased with the increase of pH value from 5.5 to 8.5. Under the experimental conditions, it was also shown that when the chlorine dosage increased from 5.46 to 21.84 ml, the TCAce formation amount increased. It was also shown that when the L-threonine dosage increased from 59.6 to 476.4 mg·L^-1, the TCAce formation amount decreased. Temperature affected the TCAce formation from L-threonine a lot, especially in the range of 10—30℃. The TCAce formation amount increased with the increase of temperature. The formation process of TCAce chlorided by L-threonine contained substitution, oxidation reaction, amino diazotation, reduction and a series of complicated reaction.

Key words: chromatography, solvent extraction, TCAce, precursor, process control, formation mechanism

摘要：

为了考察饮用水中消毒副产物三氯丙酮（TCAce）的形成过程和影响因素，采用气相色谱-质谱法，以甲基叔丁基醚为萃取剂，1,2-二溴丙烷为内标物，建立了消毒副产物三氯丙酮（TCAce）的测定方法。以L-苏氨酸为前体，考察在不同反应条件下三氯丙酮的生成效果，并探讨了TCAce的形成途径。结果表明：TCAce的生成量在碱性条件下高于中性和酸性条件，在5.5~8.5的pH范围内，随着pH的增大而逐渐提高。在试验条件下，当氯投加量由5.46 ml增加到21.84 ml时，TCAce的生成量随投氯量的增加而增加。当前体物L-苏氨酸投加量由59.6 mg·L^-1增加到476.4 mg·L^-1时，TCAce的生成量随投加量的增大而减小，当反应温度由10℃增加到30℃时，TCAce的生成量随之增加。HClO氯化L-苏氨酸形成TCAce的过程包含7个步骤，包括取代、氧化、氨基重氮化和还原等复杂的过程。

关键词: 色谱, 溶剂萃取, 三氯丙酮, 前体, 过程控制, 形成机制