为探究次氯酸钠和二氧化氯+次氯酸钠消毒后生活饮用水中4种三卤甲烷[THMs，包括三氯甲烷（TCM）、二氯一溴甲烷（DCBM）、一氯二溴甲烷（DBCM）和三溴甲烷（TBM）]生成量以及生成比例的变化，进行了题示研究。将水样（稳定剂为抗坏血酸）充满40 mL吹扫捕集瓶中，加入10.0 mg·L^-1内标（氟苯）使用液10.0 μL，旋紧瓶盖，振荡1 min后分取5 mL，在吹扫温度30℃、吹扫时间9.0 min、吹扫流量40 mL·min^-1、解吸温度225℃、解吸时间2.0 min等条件下吹扫捕集，所得气体进入气相色谱-质谱仪，在DB-5MS石英毛细管色谱柱（60 m×0.32 mm，1.0 μm）上进行程序升温分离（初始柱温为45℃），所得4种THMs用电子轰击离子（EI）源电离，以选择离子监测（SIM）模式检测，内标法定量。结果显示，4种THMs与内标的质量浓度比值均在一定范围内与其对应的峰面积比值呈线性关系，检出限（3s）为0.027~0.030 μg·L^-1；分别以无本底水和管网水为基质进行3个浓度水平的加标回收试验，回收率为88.1%~105%，测定值的相对标准偏差（n=6）为1.7%~4.7%。方法用于深圳市3家水厂76份生活饮用水样品中4种THMs的分析，各水厂水样中4种THMs的检出量和总量均未超过GB 5749-2022规定的限值；采用单一次氯酸钠消毒的水样中各THMs检出量占各THMs限值比值的加和（THMs^*值）存在超标风险：采用二氧化氯＋次氯酸钠消毒的水样中TCM的检出量和THMs总量均降低了近50%，TCM检出量占THMs总量的比值降低，其余3种溴代THMs的比值增加，并且次氯酸钠的投放量和投放次数显著降低，THMs^*值超标风险降低，建议相关水厂在夏季高温多雨时，及时关注水源水质的变化，必要时采用二氧化氯＋次氯酸钠联合消毒方式。

The title study was conducted to investigate the changes in the generation amount and proportion of 4 trihalomethanes (THMs, including TCM, DCBM, DBCM and TBM) in drinking water after disinfection with sodium hypochlorite and chlorine dioxide+sodium hypochlorite. Water sample (stabilized by ascorbic acid) was taken and filled into a 40 mL-purge-and-trap bottle, and 10.0 μL of 10.0 mg·L^-1 internal standard (fluorobenzene) solution was added. After tightening the bottle cap, the mixture was shaken for 1 min, and an aliquot (5 mL) was taken for purge-and-trap with purge temperature of 30℃, purge time of 9.0 min, purge flow of 40 mL·min^-1, desorption temperature of 225℃, and desorption time of 2.0 min. The resulting gas was introduced into the gas chromatograph-mass spectrometer, and the 4 THMs were separated on DB-5MS quartz capillary column (60 m×0.32 mm, 1.0 μm) by temperature program with initial column temperature of 45℃, ionized by EI source, detected by SIM mode, and quantified by internal standard method. It was shown that linear relationships between values of the mass concentration ratio and the corresponding peak area ratio of the 4 THMs to the internal standard were kept in definite ranges, with detection limits (3s) in the range of 0.027-0.030 μg·L^-1. The spiked recovery test was made at the 3 concentration levels using baseless water and pipeline water as substrates, giving recoveries in the range of 88.1%-105%, and RSDs (n=6) of the determined values in the range of 1.7%-4.7%. The proposed method was used for analyzing the 4 THMs in 76 drinking water samples from 3 water plants in Shenzhen. The detection amounts of 4 THMs and total amount in water samples from each water plant did not exceed the limits specified by GB 5749-2022. The sum (THMs^* value) of the ratios of the detection amount to the limit of each THMs in the water samples disinfected with a single disinfectant of sodium hypochlorite posed a risk of exceeding the limit. The detection amount of TCM and the total amount of THMs in the water samples disinfected by chlorine dioxide+sodium hypochlorite decreased by nearly 50%, the ratio of TCM detection amount to the total amount of THMs decreased, the ratio of the other three bromotrichloromethanes increased, and the amount and frequency of sodium hypochlorite dropped significantly, reducing the risk of THMs^* value exceeding the standard. It was suggested that relevant water plants focused on changes in water quality during hot and rainy summer, and used the combined disinfection method of chlorine dioxide and sodium hypochlorite if necessary.