Quantification of dichloroiodomethane and bromochloroiodomethane in human blood by solid-phase microextraction coupled with gas chromatography-high-resolution mass spectrometry

Iodine-containing trihalomethanes (iodo-THMs) are formed as disinfection byproducts when iodide-containing water is disinfected using chloramination process. Subsequent water use may lead to human exposure to iodo-THMs. Because of health concerns surrounding exposure to iodo-THMs, a rapid, reliable, and high-throughput analytical method was developed to quantify trace levels of two iodo-THMs: dichloroiodomethane (IDCM) and bromochloroiodomethane (IBCM) in human blood. These analytes from the headspace above blood samples were extracted using solid-phase microextraction. Analytes were then desorbed and separated by capillary gas chromatography and analyzed by high-resolution mass spectrometry with multiple ion monitoring. This method utilizes stable isotope dilution to quantify parts-per-trillion levels of all analytes, with excellent precision of < 9% coefficient of variation. At three spiked levels, method accuracy of IDCM and IBCM ranged between 6 and 20% difference when comparing spiked and measured amounts. The method limit of detection was 2 ng/L for both IDCM and IBCM. This selective, sensitive, and rapid method will help to assess human exposure to iodo-THMs and to study potential associations between exposure and adverse health outcomes.