Development of a Multiresidue Method for Analyzing Pesticide Traces in Water Based on Solid-Phase Extraction and Electrospray Liquid Chromatography Mass Spectrometry

Abstract

The GC/MS technique is still the staple for analyzing pesticide residues in water. However, many of the currentuse pesticides are not amenable to GC/MS analysis. As shown recently in some published reports, the LC/MS technique could fill this gap. We developed a sensitive and specific LC/MS method for determining 45 widely used pesticides having a broad range of polarity in water. This method involves passing 4, 2, and 1 L, respectively, of drinking water, groundwater, and river water through a 0.5-g graphitized carbon black (Carbograph 4) cartridge at ca. 100 mL/min. In all cases, recoveries of the analytes were better than 80%, except for carbendazim (76%). The performance of the electrospray/mass spectrometer (ES/ MS) detector was optimized by adopting in-glass distilled methanol as the organic modifier and 10 µmol/L trifluoroacetic acid as an additive to the mobile phase. The effects of varying the electrical field in the ES/MS transport region on both sensitivity and specificity of the detector were evaluated. The in-source collision-induced decomposition process afforded great specificity of the method, at little or no expense of sensitivity. For drinking water, the limits of detection (LODs) were calculated from both total ion current chromatograms and extracted ion current profiles. In the former case, LODs ranged between 1 (atrazine) and 9 (butoxycarboxim) ng/L. In the latter case, LODs ranged between 0.06 (malathion) and 1.5 (aldicarb sulfone) ng/L.

Composition, Distribution, and Characterization of Suspected Endocrine-Disrupting Pesticides in Beijing GuanTing Reservoir (GTR)

“…Common preconcentrations of water samples include liquid-liquid extraction (LLE) (US EPA 1984;Tan 1992), solid phase microextraction (SPME) (Aguilar et al 1998;Boyd-Boland et al 1996;Magdic and Pawliszyn 1996), supercritical fluids extraction (SFE) (Nerin et al 1998;Fatoki and Awofolu 2003), and solid-phase extraction (SPE) (Chris et al 1990;Lacorte et al 1993;Albanis and Hela 1995;Crescenzi et al 1997;Quayle et al 1997). SPE is described to provide cleaner extracts, less solvent handling, and equivalent or better recoveries than conventional solvent extraction techniques, and thus SPE techniques for the extraction of pesticide multi-residues from aquatic systems have attracted considerable attention and are widely reported in the literature (Chris et al 1990;Lacorte et al 1993;Albanis and the 1995;Crescenzi et al 1997;Nogueira et al 2004). The use of gas chromatography (GC) with electron capture detection (ECD) for the detection of pesticide multi-residues is common because of its high resolution and good sensitivity in the nanogram range (Tan 1992;Codex Alimentarius 1993;Tolosa et al 1996;Quayle et al 1997;Vassilakis et al 1998;Fatoki and Awofolu 2003).…”

Simultaneous determination of carbamate and organophosphorus pesticides in fruits and vegetables by liquid chromatography–mass spectrometry

“…This is most likely due to the fact that acetonitrile is a weaker proton donor than methanol (both in aqueous phase and in gaseous phase as well). Methanol was suitable for obtaining high intensity of all carbamates since it is liable to provide hydrogen to the radical ion of carbamates [12]. For optimal LC separation, the more formic acid that was added to the mobile phase, the better resolution obtained for pesticides especially for those solute pairs such as pirimiphosmethyl and etrimfos which were difficult to be separated.…”

Analysis of Triazines and Associated Metabolites with Electrospray Ionization Field-Asymmetric Ion Mobility Spectrometry/Mass Spectrometry

“…A sample handling scheme involving solid-phase extraction (SPE) with graphitized carbon black followed by liquid chromatography (LC) with ultraviolet (UV) and massselective detection has been presented for dealing with pesticides, including atrazine. [6][7][8] In these studies, SPE concentration factors were of the order of 10 4 . The intrinsic sensitivity of the mass spectrometer (MS) was about 20 ppb; including SPE the LOD was 3 to 30 ppt depending on the nature of the aqueous matrix 6 (even LOD as low as 0.2 ppt has been reported 9 ).…”