Quantitative Analyses of Microcystins by LC-MS/MS using an Orbitrap Fusion Tribrid Mass Spectrometer

摘要

An HPLC system was coupled to an orbitrap mass spectrometer for the identification and quantification of MC-LR using LC-SIM-MS and LC-MS/MS. LC-SIM-MS quantitation of MC-LR was performed by integrating the EIC peak of the singly-charged protonated ion (m/z 995.56). The peak intensities of MC-LR standards were very reproducible, and were used to quantify MC-LR in water samples by LC-SIM-MS. A calibration curve was constructed for MC-LR in the concentration range between 25 ppt (LOQ) and 10 ppb without preconcentration before LC-SIM-MS analyses. A reproducible SPE method was developed enabling high recovery of MC-LR (> 98%) during the purification and preconcentration steps before LC-MS analyses. The preconcentration of MC-LR enabled quantification in the concentration range between 500 ppq (LOQ) and 35 ppt by LC-SIM-MS. MC-LR was reproducibly analyzed (≤ 5% error) in more complex samples such as tap water and in mixtures with MC-LA and MC-RR. Quantification of MC-LR was performed using LC-MS/MS using the intensity of the most intense fragment ion peak (m/z 135.08). LC-MS/MS calibration curves were constructed for MC-LR with (7 ppt - 35 ppt) and without preconcentration (200 ppt - 10 ppb). High-mass accuracy capabilities (< 3ppm) of the orbitrap mass analyzer was utilized for quantification of MC-LR. SPE recovery and preconcentration method developed and LC-SIM-MS enable sensitive, selective, and reproducible quantification of MC-LR.