ABSTRACT
Objective To explore the residual level of FPMs in indoor dust samples in Shenzhen from 2020 and 2021, and to analyze its temporal distribution characteristics. Methods In the present study, indoor dust samples (n=193) from residential buildings in Shenzhen. were collected to analyze the temporal variation characteristics of FPMs. Ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was applied to determine the concentrations of FP and its four major metabolites (fipronil-sulfone, fipronil-sulfide, fipronil-desulfinyl, and fipronil-amide; abbreviated as FP-SFO, FP-SFI, FP-DES, and FP-AM) in the samples. The sum of the concentrations of FP and its four metabolites was represented as additive mass concentration (ΣFPMs). Additionaly, Wilcoxon test was performed to determine the temporal distribution differences of FPMs’ concentrations. Results From 2020 to 2021, the concentration of ΣFPMs for the in door dust samples in Shenzhen ranged from 0.51 to 4 415 ng/g (median: 18.8ng/g). FP, FP-SFO AND FP-SFI were the major target analytes in the sample with detection rates of 90.60%，86.20% and 75.40%, respectively. The detection rates of other metabolites were low (≤ 44.3%). Analysis of the temporal variation trend of FPMs’ concentrations showed that there was no significant difference in the levels of ΣFPMs between warm season（spring and summer）and cold season（autumn and winter）in the indoor dust samples from 2020 to 2021(2.38 vs 2.84ng/g , P > 0.05). However , the concentrations of FP-SFI and ΣFPMs in the indoor dust samples collected from 2021 showed an significantly increasing trend compared with 2020（1.02 vs 1.89 , 17.80vs. 20.10 ng/g , P < 0.05). Conclusion From 2020 to 2021 , the detection level of FPMs in indoor dust in Shenzhen is relatively high and shows an upward trend , with no obvious seasonal difference. However, whether the residual level of FPMs in indoor dust poses a risk to human health needs further study.