Evaluation of supercritical fluid chromatography coupled to tandem mass spectrometry for pesticide residues in food
V. Cutillas, M. Martínez Galera, Ł. Rajski, A. R. Fernández-Alba
European Union Reference Laboratory for Pesticide Residues in Fruit & Vegetables, University of Almeria, Agrifood Campus of International Excellence(ceiA3) Department of Hydrogeology and Analytical Chemistry, Ctra. Sacramento S/N◦, La Cañada de San Urbano, 04120, Almería, Spain
Journal of Chromatography A (2018) Volume 1545, April 2018, Pages 67-74
(https://doi.org/10.1016/j.chroma.2018.02.048)
Abstract
Supercritical fluid chromatography coupled to triple quadrupole mass spectrometry has been evaluated for pesticide residues in food. In order to check its advantages and limitations it was developed a method to identify and quantify 164 pesticides in three different matrices (tomato, orange and leek). A carbon dioxide gradient with methanol (containing 1 mM ammonium formate) was used allowing a flow rate of 1.5 mL/min that made the total run time of 12 min without any problem of overpressure. Addition of a post column flow 150 μL/min of Methanol with ammonium formate/formic acid was necessary to improve the ionization.
The matrix effect study revealed that the percentages of pesticides with irrelevant matrix effect (suppression lower than 20%) was 99% in tomato, 87% in orange and 62% in leek, whereas significant suppression (higher than 50%) was not found in tomato and only 1% of the compounds in orange and 3% in leek.These results compare favorably with that typically obtained in LC–MS/MS. The absence of water in the mobile phase, also provided some important advantages regarding LC–MS/MS as (i) higher retention of polar compounds in the column, which elute with high sensitivity and good peak shape and (ii) a general increase of the sensitivity of the analysis, consequence of the high ionization and ion extraction efficiency.
Pesticides evaluated were identified following the SANTE/11813/2017. At the spiking concentration of 5 μg/kg, 98% of the pesticides were identified in tomato, 98% in orange and 94% in leek, whereas for the concentration of 10 μg/kg all the compounds were identified in tomato and only spiromesifen was not identified in orange and leek. At the concentration of 20 μg/kg, spiromesifen was also identified in these two matrices. The linearity and reproducibility of the method were evaluated with results which guarantee high quality in the analytical measurements. Even though only 2 μL of final extract were injected, the sensitivity of the SFC method was enough to achieve stringent LOQs.Real samples, including 6 different fruits and vegetables, were analyzed by the SFC-MS/MS proposed method, the results being similar to those obtained by LC–MS/MS. The method was also applied to a proficiency test of fipronil in eggs with good results in all the cases.
Carbon dioxide as mobile phase with methanol as modifier can represent a good alternative to LC–MS/MS with reduction of matrix effects and shorter run times.
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Published 17-05-2019, 15:37:55
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