Organochlorine Pesticides by LC−MS

Abstract

Contamination of water resources by organochlorine pesticides (OCPs) continues to receive widespread attention because of the increasing concern regarding their high persistence and bioaccumulation. These organic pollutants are not amenable by liquid chromatography (LC) coupled to atmospheric pressure ionization-mass spectrometry, which represents the method of choice for the characterization of pesticide residues in water. Gas chromatography-mass spectrometry provides excellent response for OCPs, but it falls short when complex, multiresidue analyses are required. As recently demonstrated, an efficient EI-based LC-MS interface can generate very good spectra for an extremely wide range of small-medium molecular weight molecules of different polarity and can represent a valid tool in solving the analytical challenge of analyzing OCPs by LC-MS. Based on this assumption, we present a new approach for the determination of 12 OCPs in water samples. The method requires a solid-phase extraction preconcentration step followed by nanoscale liquid chromatography coupled to a direct-electron ionization direct interface (Direct-EI). Direct-EI is a miniaturized interface for efficiently coupling a liquid chromatograph with an EI mass spectrometer. The capability to acquire high-quality EI spectra in a wide range of concentrations, and to operate in selected ion monitoring mode during analyses, allowed a precise quantification of the OCPs. Without sample injection enrichment, limits of detection of the method span from 0.044 to 0.33 microg/L, corresponding to an instrumental detection limit of 120-850 pg. In addition, a careful evaluation of the matrix effect showed that the response of the Direct-EI interface was never affected by sample interferences. From our knowledge, the proposed method represents the first application of LC-MS in the analysis of organochlorine pesticides.

Current mass spectrometry strategies for the analysis of pesticides and their metabolites in food and water matrices

“…Direct-EI is a miniaturized interface for efficiently coupling of LC with an electron ionization (EI) source and a single quadrupole analyzer (Cappiello et al, 2007). Direct-EI has been applied to the determination of 12 OCPs in water samples in conjunction with nanoscale LC (Famiglini et al, 2008). The comparison between the recorded EI spectra versus the NIST reference library was found satisfactory for the compounds investigated and allowed the determination of the majority of the organochlorine compounds at levels established by the EU Legislation for the quality of drinking water.…”

A fully automated system with on-line micro solid-phase extraction combined with capillary liquid chromatography–tandem mass spectrometry for high throughput analysis of microcystins and nodularin-R in tap water and lake water

“…Consequently, it has not been frequently employed until now. Famiglini et al compared the performances of microSPE with traditional SPE followed by capillary LC-ESI/MS for the analysis of 4 pesticides from aqueous samples [20]. Better recoveries were obtained when microSPE traps were used.…”

A quick, easy, cheap, effective, rugged, and safe method for the simultaneous detection of four triazolone herbicides in cereals combined with ultrahigh performance liquid chromatography with tandem mass spectrometry

“…It is well known that matrix effects (an unexpected suppression or enhancement of the analyte response due to coeluting sample constituents) are a major challenge in the analysis of pesticide residues in complex samples using LC−MS . Matrix effects depend on the instrument, the type and amount of matrix, the sample pretreatment procedure, and the type and concentration of the analyte . Therefore, in this paper, we investigated the matrix effects on the MS/MS detector using the proposed method by comparing the standards in the solvent with the matrix‐matched standards.…”