title: Evaluation of the matrix-like effect in multiresidue pesticide analysis by gas chromatography with tandem mass spectrometry.
abstract: In multiresidue pesticide analysis using gas chromatography, it has long been recognized that an increase in the number of pesticides present in a standard solution can result in an enhancement of the peak responses of certain pesticides. Despite being widely acknowledged, this phenomenon has been rarely studied and is poorly understood. In this study, the authors have tentatively called this phenomenon the "matrix-like effect" and demonstrated it clearly using gas chromatography with tandem mass spectrometry. Five selected pesticides, namely, omethoate, terbufos, malathion, procymidone, and permethrin, and four internal standard candidates, namely, triphenyl phosphate, naphthalene-d8, phenanthrene-d10, and fluoranthene-d10, were used to evaluate the matrix-like effect following the addition of 58, 108, and 166 other pesticides. With the exception of naphthalene-d8, the responses of all evaluated pesticides and internal standard candidates were dramatically enhanced by the addition of up to 166 coexisting pesticides. The relative response factors of the five pesticides to each internal standard candidate were not constant under the conditions studied, meaning that these internal standard candidates did not adequately compensate for the matrix-like effect, at least for the five evaluated pesticides. The results revealed that the presence of various mixtures of pesticides in standard solutions might act as an unintentional analyte protectant, that is, some sort of troublesome "quasi-matrix."
authors.affiliation: Department of Food, Drugs and Environment, Osaka Prefectural Institute of Public Health, Higashinari-ku, Osaka, Japan.
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Akutsu
authors.affiliation: Department of Food, Drugs and Environment, Osaka Prefectural Institute of Public Health, Higashinari-ku, Osaka, Japan.
authors.forename: Masato
authors.initials: M
authors.lastname: Yoshimitsu
authors.affiliation: Department of Food, Drugs and Environment, Osaka Prefectural Institute of Public Health, Higashinari-ku, Osaka, Japan.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Kitagawa
authors.affiliation: Department of Food, Drugs and Environment, Osaka Prefectural Institute of Public Health, Higashinari-ku, Osaka, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Takatori
authors.affiliation: Department of Food, Drugs and Environment, Osaka Prefectural Institute of Public Health, Higashinari-ku, Osaka, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Fukui
authors.affiliation: Department of Food, Drugs and Environment, Osaka Prefectural Institute of Public Health, Higashinari-ku, Osaka, Japan.
authors.forename: Masakazu
authors.initials: M
authors.lastname: Osakada
authors.affiliation: Department of Food, Drugs and Environment, Osaka Prefectural Institute of Public Health, Higashinari-ku, Osaka, Japan.
authors.forename: Satoko
authors.initials: S
authors.lastname: Yamaguchi
authors.affiliation: Department of Food, Drugs and Environment, Osaka Prefectural Institute of Public Health, Higashinari-ku, Osaka, Japan.
authors.forename: Keiji
authors.initials: K
authors.lastname: Kajimura
authors.affiliation: Department of Food, Drugs and Environment, Osaka Prefectural Institute of Public Health, Higashinari-ku, Osaka, Japan.
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Obana
authors.affiliation: Food and Drug Safety Center, Hatano Research Institute, Hadano, Kanagawa, Japan.
authors.forename: Takaho
authors.initials: T
authors.lastname: Watanabe
keywords: matrix-like effect; pesticide residue analysis; response enhancement