LAUSR

Commercially available headspace solid‐phase microextraction (HS‐SPME) fibers have been used for years to extract pesticides and polychlorinated biphenyls from aqueous samples at the expected ultratrace levels (picograms per liter or parts per quadrillion) in alpine lakes. Several variables of the HS‐SPME technique have been adequately evaluated, including water temperature, pH, salt content, fiber type and coating thickness, length of fiber‐sample exposure, and liquid immersion versus headspace exposure; but surprisingly, analyte recovery as a function of analyte concentration and storage time has not been included in previous studies, which can be important for remote sampling sites. Seven hydrophobic chlorinated pollutants were identified in alpine lake water (out of 54 analyzed); but recovery using the common SPME technique was found to be inconsistent as the analyte concentration decreases, and the recovery trend as a function of concentration varies on a compound‐to‐compound basis that could result in a large underestimation of analyte concentrations in field samples. Of the 54 compounds surveyed, o,p′‐dichlorodiphenyltrichloroethane (DDT), p,p′‐DDT, p,p′‐dichlorodiphenyldichloroethylene (DDE), o,p′‐DDE, chlorthal‐dimethyl, endosulfan I, γ‐hexachlorocyclohexane, heptachlor, and trans‐nonachlor were generally measured at concentrations between 1 and 150 pg/L (parts per quadrillion). No study to date has evaluated this commonly used but unstandardized technique for analyte recovery as a function of analyte concentration or storage time of aqueous samples. Environ Toxicol Chem 2023;42:1199–1211. © 2023 SETAC