Determination of Chlormequat in Pears by Liquid Chromatography/Mass Spectrometry

Abstract

A straightforward and reliable method was developed for the determination of chlormequat in pears by liquid chromatography/mass spectrometry (LC/MS). Water and methanol were compared as extraction solvents. Because no significant differences in extraction efficiency or repeatability were found, water was chosen as the extraction solvent. The extracts were analyzed without cleanup by either an ion-trap liquid chromatograph/mass spectrometer in the single MS mode or a triple-quadrupole instrument in the MS/MS mode, using electrospray ionization. Both instruments were equally suitable for quantitation and confirmation of identity. Recoveries were 76–103%, and reproducibility was ≤12%. The lowest detection limit (0.007 mg/kg) was obtained with the triple-quadrupole instrument in the MS/MS mode.

Control of pesticide residues by liquid chromatography‐mass spectrometry to ensure food safety

“… LC/MS/MS chromatograms of chlormequat in pear samples obtained with the QqQ instrument ( A ) and LC/MS chromatogram of chlormequat in pear samples obtained with the QIT instrument ( B ) of a pear blank spiked at 0.1 mg/kg (0.02 µg/mL) and pear blank. Adapted from the publication of Mol et al (2000), with permission from the AOAC International. Copyright 2000.…”

“…They are commonly elaborated for very new pesticides that lately are incorporated to multi‐residue methods (Nunes et al, 2000; Hiemstra & de Kok, 2002; Hengel et al, 2003; Pozo et al, 2003; Sancho et al, 2003; Hall et al, 2004; Hetmanski et al, 2004; Winrow, Hird, & Brown, 2003; Schwedler, Thomas, & Yeh, 2000) or for those that have special characteristics, such as being ionic, and cannot be incorporated into a traditional multi‐residue scheme. The most typical examples are ammonium quaternary growth regulators (Hau et al, 2000; Mol et al, 2000; Evans et al, 2000a,b; Granby & Vahl, 2001; Peeters et al, 2001; Careri et al, 2002; Riediker et al, 2002; Castro, Moyano, & Galceran, 2001), glyphosate (Granby & Vahl, 2001), fosetyl aluminum (Hernández et al, 2003), and cyromazine (Sancho et al, 2005). The sample pre‐treatments are based on extraction with water or methanol, and off‐ or on‐line cleanup using ion exchange resins or SPE cartridges.…”

“…Although considered as one of the most powerful techniques for structure interpretation, QIT has been seldomly used in the analysis of pesticide residues in complex matrices such as fruits and vegetables. Recently, some papers dealing with the determination of chlormequat (Mol et al, 2000; Evans et al, 2000b; Castro, Moyano, & Galceran, 2001) in food samples have been published. However, they are single residue methods used for determining only one pesticide.…”

Environmental and food applications of LC–tandem mass spectrometry in pesticide‐residue analysis: An overview

“…However, they are rather laborious and time‐consuming, and large volumes of toxic extraction solvents are used. The methods are based on extraction with water‐miscible (Bean & Henion, 1997; Vahl, Graven, & Juhler, 1998; Volmer, 1998; Juhler & Vahl, 1999; Mol et al, 1999, 2000; Startin et al, 1999; Bolygo & Boseley, 2000; Evans et al, 2000b; Hau et al, 2000; Hogenboom et al, 2000; Bester et al, 2001; Castro, Moyano, & Galceran, 2001a; Choi, Hercules, & Gusev, 2001a,b; Pozo et al, 2001; Careri et al, 2002; CEN, 2002; Riedeker et al, 2002; Taylor et al, 2002; Bonmatin et al, 2003) or water‐immiscible solvents (Stout et al, 1998). Those extracts are usually subjected to different clean‐up procedures such as liquid–liquid partitioning (Volmer, 1998; Bester et al, 2001; Choi, Hercules, & Gusev, 2001a,b; Bonmatin et al, 2003), gel permeation (Bester et al, 2001), SPE (Vahl, Graven, & Juhler, 1998; Volmer, 1998; Juhler & Vahl, 1999; Mol et al, 1999; Bolygo & Boseley, 2000; Pozo et al, 2001; Castro, Moyano, & Galceran, 2001a; Choi, Hercules, & Gusev, 2001a,b; Bonmatin et al, 2003), or ion exchange (Hau et al, 2000; Riedeker et al, 2002).…”

“…When it is used in the NI mode, electronegative compounds attach an electron, to become negatively charged. On the other hand, it is known that liquid‐phase chemistry plays a key role in the ion formation on ES, which is an interface that works well on any compound that is ionized in solution, such as ammonium quaternary compounds and acidic herbicides (Evans et al, 2000a, 2001; Jeannot et al, 2000; Mol et al, 2000; Castro, Moyano, & Galceran, 2001b; Goodwin et al, 2003). Although the conceptual approaches, such as the ionization‐continuum diagram, can be helpful to select between an APCI and ES source (Thurman, Ferrer, & Barceló, 2001), there are a great number of pesticides that can be determined by APCI and ES with an adequate sensitivity (Rule, Mordehai, & Henion, 1994; Bell et al, 1997; Baumann et al, 2000; Sancho et al, 2002; Draper, 2003; Zrotlikova et al, 2003).…”