Rapid quantification of highly polar trimethyl phosphate in wastewater via direct analysis in real-time mass spectrometry

Trimethyl phosphate (TMP) is used extensively in industrial chemical processes. Due to the high polarity and volatility, methods for its quantification in environmental samples have not been well developed. Currently, the pollution status of TMP in the environment still has not been quantitatively analyzed. This study quantifies the TMP levels in environmental water via direct analysis real-time ionization source interfaced with a triple quadrupole mass spectrometer (DART-MS/MS) with multiple reaction monitoring (MRM). The DART parameters were optimized to achieve the most TMP-sensitive MRM responses. The water samples were analyzed directly, and an isotope-labeled internal standard (ISTD) method was applied for quantification. The method exhibits significant linearity (R > 0.998) in the range of 0.05–100 ng/mL, with a limit of quantification (LOQ) of 50 pg/mL. TMP has been accurately detected in the influent and effluent water of two municipal wastewater treatment plants and a river located in Beijing. Recovery of TMP ranged 88.0–107.6% for the spiked real water samples. The results demonstrated that TMP has been existed in environmental water, and DART-MS/MS can be used for the monitoring of the pollution status and the environmental process of TMP in environmental water.