MSPD Combined With Fast GC for Ultratrace Analysis of Pesticide Residues in Non-Fatty Food
Michal Kirchner,a and Jaap de Zeeuwb
a Faculty of Chemical and Food Technology, Slovak University of Technology, Radlinského 9, 812 37 Bratislava, Slovakia,
b Varian International B.V., Herculesweg 8, P.O. Box 8033, 4330 EA, Middelburg, The Netherlands
Matrix solid phase dispersion (MSPD) sample preparation method was combined with fast gas chromatography (GC) to determine pesticide residues of different volatility and polarity at ultratrace concentration level. Apples as representatives of a non-fatty food were chosen as a matrix; they are also a common raw material for baby food production. At fast GC conditions with electron capture detection (ECD) several parameters of MSPD procedure were optimised. Sample is homogenized with sorbent Florisil, pesticides are eluted with the optimised volume of etylacetate. After evaporation of solvent to dryness, reconstitution of the rest to toluene follows and the final extract is injected utilising splitless injection. These optimised procedure leads to recoveries ³ 90% (at concentration level of 60 mg kg–1) and limits of quantification (LOQs) < 47 mg kg–1 (except of diazinon) utilizing ECD. Except of dimethoate all LOQs are lower than related maximum residual limits (MRLs) set for commodity apple. Also the possibilities of mass spectrometric (MS) detection were studied. Even at the half pre-concentration factor LOQs for all pesticides were lower than 10 mg kg–1, the MRL for baby food. Acceptable recoveries were obtained even at concentration level of 5 mg kg–1 (³ 79%).
Key words: MSPD, fast GC, pesticide residues, apples, matrix-effects