Multiresidue determination method for organophosphorus pesticides in serum and whole blood by gas chromatography-mass-selective detection.

This paper describes a rapid, specific and sensitive method for the determination of 29 organophosphorus pesticides in blood and serum, involving a rapid solid-phase extraction procedure using Oasis HLB cartridges and gas chromatography coupled to mass-selective detection. The ionization was performed by electron Impact and acquisition in the single ion monitoring mode followed three specific ions per analyte. Extraction recoveries were satisfactory and ranged between 40 and 108% in blood and serum. Limits of detection ranged from 5 to 25 ng/ml and limits of quantitation (LOQs) ranged from 10 to 50 ng/ml, in blood and serum. An excellent linearity was observed from these LOQs up to 1000 ng/ml. Intra- and inter-assay precision and accuracy were satisfactory for most of the pesticides analyzed.

Liquid chromatography-electrospray mass spectrometry multi-residue determination of pesticides in apples and pears.

This paper describes a rapid, specific and sensitive multi-residue method for the routine quantitative analysis of pesticides of several classes used for the treatment of apples and pears, down to their respective maximum residue limits (MRLs). It involves a rapid extraction procedure and liquid chromatography coupled to electrospray mass selective detection. Seven pesticides were extracted at pH 4.5 with a mixture of acetone-dichloromethane-hexane (50:20:30, v/v/v). Ionization was performed at atmospheric pressure in an electrospray-type source and detection was carried out using the selected ion monitoring (SIM) mode. Extraction recoveries were between 55 and 98% except for methylthiophanate (< 20%). Limits of detection (LODs) and limits of quantitation (LOQs) ranged, respectively, from 0.01 to 0.02 mg/kg and from 0.02 to 0.05 mg/kg, with relative standard deviation (R.S.D.) less than 19%. An excellent linearity was observed for LOQs up to 5 mg/kg. Intermediate ("inter-assay") precision and accuracy were satisfactory. The method was applied to many fruit samples intended for commercialization.

Multiresidue determination of pesticides in apples and pears by gas chromatography-mass spectrometry.

This paper describes a rapid, specific and sensitive multiresidue method for the routine analysis of several classes of pesticides used for the treatment of apples and pears, involving a rapid extraction procedure at pH 4.5 with a mixture of acetone-dichloromethane-hexane (50:20:30, v/v/v) and gas chromatography coupled to mass-selective detection, in order to achieve quantitative analysis down to their respective maximum residue limit. Extraction recoveries were between 55 and 98%. Limits of detection and limits of quantitation ranged respectively, from 0.01 to 0.05 mg/kg and from 0.02 to 0.1 mg/kg. Intra-assay relative standard deviation was less than 19% for all compounds. An excellent linearity was observed from these LOQs up to 500 mg/kg. Intermediate (inter-assay) precision and accuracy were satisfactory. The method has been applied to many fruit samples intended for commercialisation.