Objective: To establish a method for the determination of 11 polyhalogenated carbazoles in drinking water by solid-phase extraction coupled with gas chromatography-mass spectrometry, so as to provide technical reference for monitoring such pollutants in aquatic environments. Methods: The temperature programming conditions of chromatography and the eluent for solid-phase extraction were optimized to improve the separation efficiency of target compounds and reduce matrix interference. A total of 1 L finished water sample from a waterworks was collected, enriched and concentrated using a HC-C18 solid-phase extraction cartridge, eluted with dichloromethane, quantitatively analyzed under the selected ion monitoring mode of gas chromatography-mass spectrometry, and corrected using surrogate standards. Working curves of 11 polyhalogenated carbazoles were established, and the limits of detection, limits of quantification, average spiked recovery rates and relative standard deviation (RSD) were calculated. Results: Under the optimized conditions, the analysis results of 11 polyhalogenated carbazoles and surrogate standards showed that all target compounds exhibited symmetrical peak shapes, low matrix interference and good resolution, meeting the requirements of quantitative and qualitative analysis. The 11 polyhalogenated carbazoles showed good linear relationships in the range of 0.1-5.0 ng/L, with all correlation coefficients ≥0.999 4. The limits of detection ranged from 0.02 to 0.08 ng/L, and the limits of quantification ranged from 0.04 to 0.25 ng/L. At spiked concentrations of 0.1, 0.2 and 1.0 ng/L, the average spiked recovery rates were 89.1%-107.6%, 97.8%-100.5% and 92.6%-100.4%, respectively, with RSD of 2.9%-9.2%, 1.0%-3.4% and 0.8%-3.1%, respectively. Conclusion The method based on solid-phase extraction-gas chromatography-mass spectrometry for the determination of 11 polyhalogenated carbazoles in drinking water demonstrates good accuracy and precision, and can be applied to the detection of polyhalogenated carbazoles in drinking water.

ObjectiveThe monitoring of fluoride in drinking water in Qingpu District was conducted to evaluate the external exposure of residents through drinking water， and to provide data support for the continuous improvement of drinking water quality in the area and the health level of residents. MethodsFrom 2016 to 2021， the pipe network water was collected from 42 monitoring points in Qingpu District， every month， and the fluoride concentration in the pipe network water was detected by ion chromatography. ResultsThe fluctuation range of fluoride concentration in drinking water in Qingpu District from 2016 to 2021 was between 0.10 and 0.96 mg·L^-1. The fluoride in drinking water did not exceed the standard， which was lower than the lower limit of the WHO recommended range. The median fluoride concentration in drinking water in the Qingcaosha water source area was 0.20 mg·L^-1， and the median fluoride concentration in drinking water in the Dianshan lake water source area was 0.44 mg·L^-1， and the difference between the two was statistically significant （Z=20.260， P<0.001）. The fluoride concentration in drinking water had a decreasing trend year by year， especially in the water supply area of Dianshan lake water system. The fluoride concentration in drinking water in Qingcaosha water source water supply area decreased relatively gently， from 0.25 mg·L^-1 in 2017 to 0.20 mg·L^-1 gradually. According to the "Chinese Residents' Dietary Nutrient Reference Intake 2013 Edition"， the requirement of 1.5 mg·d^-1 of suitable fluoride intake （AI） for adults. About 50% of the residents in the water supply area of Dianshan lake would consume less than0.75 mg·d^-1， fluoride through drinking water， which was lower than 1/2 of the AI value. The fluoride content in the water supply area of Qingcaosha water source was relatively low， and 75% of the residents ingested fluoride through drinking water was lower than 0.37 mg·d^-1， which was lower than the 1/4 of the AI value. ConclusionThe concentration of fluoride in drinking water in Qingpu District is lower than the sanitary standard of drinking water in China，and the risk of excessive fluoride exposure is very low. However， the fluoride concentration in drinking water has a decreasing trend year by year， and intervention measures should be used rationally to reduce the health risks caused by insufficient fluoride intake.