Struger, John, et al. Bulletin of environmental contamination and toxicology, 2016, 96, 423-431.
Carbamate compounds (e.g., carbofuran) are widely used as insecticides, fungicides, herbicides, etc. in agriculture. This work measured the presence and distribution of carbamate pesticides and metalaxyl in surface waters of southern Ontario by liquid chromatography-tandem mass spectrometry (LC/MS/MS) analysis, with isotopically labeled compounds added as internal standards.
Sample preparation and analysis
· Water samples (500 mL) were extracted using SPE cartridges, which were conditioned sequentially with 10 mL of a dichloromethane/methanol (80/20) mixture, followed by 10 mL of methanol and 10 mL of deionized water. The samples were extracted at a rate of 5 mL/min, and the cartridges were dried in-line with nitrogen gas for one minute. Subsequently, the cartridges were eluted with 4 mL of methanol and 8 mL of an 80/20 dichloromethane/methanol mixture at a flow rate of 2 mL/min. The extract was then solvent-exchanged into methanol and concentrated to 0.9 mL for LC/MS/MS analysis.
· Before the analysis, 100 μL of an internal standard solution containing oxamyl-d3, carbofuran-d3, and aldicarb-d3 was added to the extracts. A high-performance liquid chromatography (HPLC) system was employed, utilizing a mobile phase of 5 mM ammonium formate in water and 90% methanol, to separate the compounds at a flow rate of 300 μL/min in positive electrospray ionization (ESI) mode. The injection volume was 5 μL into a mass spectrometer equipped with an ESI source operating in positive mode.
