The LC-MS/MS analysis of pesticides in water and sediments upon positive ESI
The LC-MS/MS analysis of pesticides in water and sediments upon positive ESI
A number of pesticides can be determined in water or sediment samples in our laboratory. For the analysis of water samples, we use a combination of large-volume injections with highly sensitive MRM acquisition. The large-volume injections save time on sample preparation and provide a solution for recovery-related problems sometimes observed using SPE preconcentration techniques. For improving the accuracy of results, the samples are spiked with 43 isotopically labeled internal standards.
For the analysis of organic contaminants in sediments, the samples are extracted with organic solvents using an accelerated solvent extractor (ASE, Dionex).
Instrumental: QTRAP 6500+ mass spectrometer (Sciex) coupled with Nexera binary UPLC (Shimadzu). The mass spectrometer was operated in positive ESI scheduled MRM mode. Chromatographic separations were carried out using the Luna Omega Polar-C18 column (2.1×150 mm, 3 µm particle size, Phenomenex) using a linear gradient of ACN/water (with 0.1% formic acid and 5 mM ammonium formate). The instrument was controlled and data were analyzed using Analyst and MultiQuant software respectively (Sciex).
Positive ESI LC-MS 314 MRM chromatograms of pesticides and internal standards (concentration of analytes, - 50 pg/ml, volume of injection - 100 µl).
LC-MS/MS (MRM) analysis using internal standards may be both, accurate and sensitive. Response of acetamiprid (left) detected at 0.5 pg/ml (ppt) concentration (volume of injection was 100 µl). The accuracy of the measured concentration was 87%.
Calibration curves of over 200 hundreds MRM transitions of pesticides.
A list of MRM parameters for pesticides determined in positive ESI mode.