Abstract
Abundant studies have been published evaluating different parameters of reverse-phase liquid chromatography (LC) and supercritical fluid chromatography (SFC), both coupled to electrospray (ESI)/mass spectrometry (MS) for pesticide residue analysis. However, there is a lack of a comprehensive comparative study that facilitates deep knowledge about the benefits of using each technique. In the present study, the same mass spectrometer was used coupled to both liquid and supercritical fluid chromatographies with a multiresidue method of 215 compounds, for the analysis of pesticide residues in food samples. Through the injection of the spiked extracts, separate experiments were conducted. A study of the optimum ion source temperature using the different chromatography modes was performed. The results were evaluated in terms of sensitivity with tomato, leek, onion, and orange as representative fruit and vegetable matrices. The compounds which reported the highest area values in each chromatography were evaluated through their substance groups and polarity values. The impact of matrix effects obtained in tomato matrix was similar for both cases; however, SFC clearly showed better results in analyzing matrices with a higher number of natural co-extracted compounds. This can be explained by the combination of two effects: (i) chromatography separation and (ii) ion source efficiency. The chromatographic elution presented different profiles of matrix components, which had diverse impact on the coelution with the analytes, being more beneficial when SFC was used in the matrices studied. The data showed that the best results obtained in SFC are also related to a higher ionization efficiency even when the ESI emitter tip was not optimized for SFC flow. In the present study a comprehensive evaluation of the benefits and drawbacks of these chromatography modes for routine pesticide residue analysis related to target compounds/commodities is provided.Graphical abstract
Highlights
Since the introduction of modern mass spectrometer devices, reverse-phase liquid chromatography (LC) has been used as the prevailing technique for the analysis of relatively polar and thermolabile pesticides [1, 2]
Very similar results were obtained with pesticides in a pure solvent at the three temperatures studied: all the compounds were identified in the 95–99% range in both chromatographic methodologies
Considering the number of pesticides not identified in each matrix, in LC we have an increase of approximately 30% per matrix compared to supercritical fluid chromatography (SFC), except in the orange matrix, where the non-identified compounds were almost twice in LC
Summary
Since the introduction of modern mass spectrometer devices, reverse-phase liquid chromatography (LC) has been used as the prevailing technique for the analysis of relatively polar and thermolabile pesticides [1, 2]. The online extraction coupled with SFC-MS/MS provides a fast and reliable determination of natural products like carotenoids and apocarotenoids in food and biological matrices [11] This type of extraction is hyphenated to SFC-MS/MS for the analysis of polycyclic aromatic hydrocarbons (PAHs) in soil matrix [12]. SFC coupled to high-resolution mass spectrometry (HRMS) provides a robust analytical method for the simultaneous quantification of persistent and mobile organic substances [13]. This type of hyphenation of HRMS with SFC is often used in the metabolomic field where the matrix effect reduction seems to improve the analysis in complex matrices like urine or plasma [14]. Preparative LC is being replaced by preparative SFC due to the advantages of using carbon dioxide as the mobile phase: high flow rate, short equilibration time, no dilution effect, and lower solvent consumption [17]
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