Determination of skin-insect repellent icaridin and DEET in human urine using solid-phase extraction and liquid chromatography with tandem mass spectrometry and its application to a sample of Japanese adults

• Published in: Environmental Health and Preventive Medicine Vol. 30; p. 18
• Main Authors: Nishihara, Nanami, Isobe, Tomohiko, Takagi, Mai, Tajima, Toshiki, Kitahara, Yugo, Hayashi, Mai, Saito, Isao, Watanabe, Satoru, Iwai-Shimada, Miyuki, Ueyama, Jun
• Format: Journal Article
• Language: English
• Published: Japan The Japanese Society for Hygiene 01.01.2025; 一般社団法人日本衛生学会; Japanese Society for Hygiene; Komiyama Printing Co. Ltd
• Subjects: Adult; Biomarkers - urine; Chromatography, High Pressure Liquid; Chromatography, Liquid; DEET; DEET - urine; East Asian People; Female; Human biomonitoring; Humans; Icaridin; Insect repellent; Insect Repellents - urine; Japan; LC-MS/MS; Male; Solid Phase Extraction - methods; Tandem Mass Spectrometry - methods; Young Adult; Japan; LC-MS/MS; Human biomonitoring; Insect repellent; Icaridin; DEET
• ISSN: 1342-078X; 1347-4715; 1347-4715
• DOI: 10.1265/ehpm.24-00220

Background: Icaridin and DEET are common insect repellents widely used on human skin and clothing (skin-insect repellents [skin-IR]) to repel common pests, such as mosquitoes and biting flies. Novel analytical methods for urinary skin-IR exposure biomarkers that can be effectively applied in epidemiological studies and provide strong evidence related to risk assessment associated with daily exposure are required. In this study, we aimed to develop a method for analyzing the concentrations of icaridin, DEET, and two DEET metabolites N,N-diethyl-3-(hydroxymethyl) benzamide and 3-(diethylcarbamoyl) benzoic acid in human urine.Methods: In this analysis, after formic acid-induced acidification of the urine sample, exposure biomarkers were extracted using solid-phase extraction composed of a modified polystyrenedivinylbenzene polymer for reversed phase (hydrophobic) retention. Subsequently, high-performance liquid chromatography-tandem mass spectrometry was performed within 10 min for a separation analysis. The present method was applied to five Japanese adults (aged 20–43 years) who used icaridin or DEET-containing products within a week.Results: Limits of detection were 0.06–0.11 µg/L. Extraction recoveries were 74%–88%. The intraday and interday variations were 1.5–17.5 and 0.9–15.8% relative standard deviation, respectively. All exposure biomarkers were successfully detected in all five adults. Urinary concentrations of exposure biomarkers reached their maximum values within 15 h after starting to use skin-IR.Conclusions: This method was successful in measuring urinary exposure biomarkers of skin-IR, including icaridin and DEET. Moreover, this study presents the first application of biomonitoring of urinary icaridin concentrations after using a commercial product.