First Evidence of Novel Organothiophosphate Esters as Prevalent New Pollutants in Dust from Automotive Repair Shops Discovered by High-Resolution Mass Spectrometry

The occurrence of organophosphorus compounds has garnered global concern due to their widespread production and potential environmental risks. Limited structural information has hindered a comprehensive understanding of their composition. By characteristic fragmentation-based nontarget analysis, the occurrence and composition of organothiophosphate esters (OTPEs), which are antiwear additives in lubricant oils that have received little attention previously, were investigated in dust from automotive repair shops and surrounding buildings. Fourteen OTPEs were tentatively identified, including four triarylphosphorothionates, six <i>O</i>,<i>O</i>-dialkyl phosphorothioates, and four <i>O</i>-alkyl <i>O</i>-alkyl sulfone phosphorothioates, among which four OTPEs were further confirmed by authentic standards or an industrial product. Triphenyl phosphorothioate (TPhPt) and tris(2,4-di-<i>tert</i>-butylphenyl) phosphorothioate (AO168=S) were prevalently detected in automotive repair shops with median concentrations of 230 and 246 ng/g, respectively, closely comparable to triphenyl phosphate (TPhP, median concentration: 302 ng/g). <i>O,O</i>-Dihexyl phosphorothioate (DHPt), <i>O,O</i>-dioctyl phosphorothioate (DOPt), <i>O</i>-hexyl <i>O</i>-hexyl sulfone phosphorothioate (DHSPt), and <i>O-</i>octyl <i>O</i>-octyl sulfone phosphorothioate (DOSPt) were the abundant analogues in automotive repair shops with semiquantitative median concentrations in the range of 119-1.05 × 10³ ng/g. Hierarchical cluster analysis showed that OTPEs exhibited similar distribution patterns across automotive repair shops, indicating that these chemicals had similar sources. Moreover, the concentrations of OTPEs were usually higher in automotive repair shops than that in surrounding buildings, suggesting a motor vehicle related emission source. To our knowledge, 12 out of the 14 detected OPTEs were reported in the environment for the first time. The discovery of these OTPEs expanded the scope of known organophosphorus pollutants, highlighting the potential contaminants of OTPEs from lubricant oils for automotive and industrial applications.