Application of Solid Phase Micro-Extraction (SPME) to the analysis of pesticide residues in vegetables

Abstract

Solid Phase Micro-Extraction (SPME) is a new analytical technique, based on capturing the analytes by adsorption onto an organic phase coating a glass ®bre, and subsequent direct desorption into the injector of a gas chromatograph. This technique has been successfully applied in the analysis of organic contaminants in water, giving linear responses and, in some cases, high sensitivities.The present paper reports data about the application of SPME to the analysis of pesticide residues in a vegetable matrix, testing over nearly one hundred active compounds, with two types of adsorbent phase (polydimethylsiloxane and Carbowax/divinylbenzene). A vegetable matrix spiked with pesticides was analyzed by SPME and by a traditional multi-residue method; recoveries were determined and compared for the two cases. The behaviour of the analytical response by SPME was studied in the range 0.01±1 mg kg À1 by adding increasing amounts of given pesticide mixtures to the vegetable matrix.The procedure was further tested by analyzing real samples, and gave some dif®culties in recovering the whole amount of some of the residues present (in comparison with the traditional method). The SPME method was then improved by pre-extracting with acetone and sonicating before the extraction/ adsorption step. The results obtained were satisfactory (some certi®ed matrices were also tested) with good accordance between the two methods. Nevertheless some active compounds showed very low responses or remained undetectable by SPME in our experimental conditions.

Use of SPME and Chemometrics in Method Development for Food and Environmental Analysis of Pesticide Residues

“…Derivitization can be applied before, during or after extraction, post derivitization only aids chromatographic separation and detection [37] e.g., dilution, centrifugation, use of organic solvent, pre-concentration [38][39][40][41][42][43]. This is done to prevent irreversible absorption of large molecules from the sample matrix, Current trends in SPME coatings [15].…”

Use of SPME and Chemometrics in Method Development for Food and Environmental Analysis of Pesticide Residues

“…For complex sample matrices which may pose difficulty in extraction such as ionic and polar compounds, it is necessary to derivitize the sample so as to make the sample extraction process easier and to aid better detection. Derivitization can be applied before, during or after extraction, post derivitization only aids chromatographic separation and detection [37] e.g., dilution, centrifugation, use of organic solvent, pre-concentration [38][39][40][41][42][43]. This is done to prevent irreversible absorption of large molecules from the sample matrix, throughout the extraction time for the absorption of the analyte of interest.…”

Headspace Solid-Phase Microextraction of Pesticide Residues in Cannabis Samples

“…Numerous SPME methods have already been reported in the literature for the analysis of these substances. They included extractions from different matrices, such as water [25][26][27], soils [28] [29], foodstuff [30][31][32], biological fluids [19][33] [34] and plants [35][36][37][38], using both types of SPME modes and several fibres.…”