Pesticides, phenols (e.g. chlorophenols), phthalates, and organotins are heavily used, and polycyclic aromatic hydrocarbons (PAHs) are emitted ubiquitously from transportation and combustion sources. The above chemicals may run off or via wet or dry deposition to the river, ground water, sediment, and soil. Since most conditions in soil and sediment are anaerobic, the above compounds may exist in the environment persistently; consequently, the residue level in soil or sediment may represent a long term trend of pollution.
This study developed a method for detecting 79 important environmental pollutants, including 11 organophosphates, 5 carbamates, 7 pyrethroids, 16 phenols, 8 phthalates, 24 PAHs (containing the 16 EPA priority PAHs), and 8 organotins, in soil and sediment, using ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). Soils and sediments samples were treated with QuEChERS and the extracts were analyzed using UPLC-MS/MS with electrospray ionization (ESI) or atmospheric pressure photoionization (APPI). Pesticides and phthalates were separated with a Phenomenex Kinetex PFP column (2.6 μm, 50 × 2.1 mm) at ESI positive mode; phenols were separated with a Waters Cortecs UPLC C18 column (1.6 μm, 30 × 2.1 mm) at ESI negative mode, and PAHs were separated with a Restek Pinnacle DB PAH UHPLC column (1.9 μm，50 × 2.1mm) at APPI positive mode. The organotins could be detected at ESI and APPI positive modes, while the linearity of calibration cureves of organotins were not so good except for fenbutatin oxide and triphenyltin. Furthermore, the organotins tend to accumulate on the cone of the MS ionization probe, resulting in a need of fragment clean up on the cone; this may damage the instrument. Other detection methods, such as the use of GC-MS with chemical derivatization, were suggested for the analysis of organotins.
This study compared the extraction efficiency of QuEChERS and sonication extraction in soil and sediment, and the former was better than the latter. The limits of detection of soil and sediment ranged from 20 to 120 ng/g (wet weight) and 30 to 180 ng/g (wet weight),respectively. The square of regression coefficients (r2) of calibration curves were higher than 0.990. The matrix effect factors of analytes were between 45-88%, and the use of isotope-labeled internal standards can cancel out the effects on quantitation resulting from matrix effects or variations of extraction efficiency, then reached good recoveries. Spiked samples and certified reference materials were used for method validation; 22 real samples, including 11 sediments, two sludge from a water treatment plant, and 9 soils, were also analyzed for method validation. Phthaltes and PAHs were in higher positive rates and the pesticide Edifenphos and Carbaryls were detected in the real samples.The results of this study can be used to establish the initial precision and recovery (IPR) and a draft of standard analytical procedure for the National Institute of Enviromental Analysis.