title: Analysis of herbicides in olive oil by liquid chromatography time-of-flight mass spectrometry.
abstract: The application of liquid chromatography time-of-flight mass spectrometry (LC/TOF-MS) for the identification and quantitation of four herbicides (simazine, atrazine, diuron, and terbuthylazine) in olive oil samples is reported here. The method includes a sample treatment step based on a preliminary liquid-liquid extraction followed by matrix solid-phase dispersion (MSPD) using aminopropyl as a sorbent material. A final cleanup step is performed with florisil using acetonitrile as an eluting solvent. The identification by LC/TOF-MS is accomplished with the accurate mass (and the subsequent generated empirical formula) of the protonated molecules [M + H]+, along with the accurate mass of the main fragment ion and the characteristic chlorine isotope cluster present in all of them. Accurate mass measurements are highly useful in this type of complex sample analyses since they allow us to achieve a high degree of specificity, often needed when other interferents are present in the matrix. The mass accuracy typically obtained is routinely better than 2 ppm. The sensitivity, linearity, precision, mass accuracy, and matrix effects are studied as well, illustrating the potential of this technique for routine quantitative analyses of herbicides in olive oil. Limits of detection (LODs) range from 1 to 5 microg/kg, which are far below the required maximum residue level (MRL) of 100 microg/kg for these herbicides in olive oil.
authors.affiliation: Pesticide Residue Research Group, University of Almería, 04120 Almería, Spain.
authors.forename: Juan F
authors.initials: JF
authors.lastname: García-Reyes
authors.forename: Carmen
authors.initials: C
authors.lastname: Ferrer
authors.forename: E Michael
authors.initials: EM
authors.lastname: Thurman
authors.forename: Amadeo R
authors.initials: AR
authors.lastname: Fernandez-Alba
authors.forename: Imma
authors.initials: I
authors.lastname: Ferrer
mesh_terms: D001280:Atrazine / Q000032:analysis; D002851:Chromatography, High Pressure Liquid; D004237:Diuron / Q000032:analysis; D006540:Herbicides / Q000032:analysis*; D000069463:Olive Oil; D010938:Plant Oils / Q000737:chemistry*; D012680:Sensitivity and Specificity; D012839:Simazine / Q000032:analysis; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D014227:Triazines / Q000032:analysis
chemical_list: D006540:Herbicides; D000069463:Olive Oil; D010938:Plant Oils; D014227:Triazines; D004237:Diuron; C037565:terbutylazine; D001280:Atrazine; D012839:Simazine