Evaluation of different QuEChERS procedures for pesticide residues determination in Calendula officinalis (L) inflorescences
2017
Besil, Natalia | Pequeño, Fiamma | Alonzo, Noel | Hladki, Ricardo | Cesio, María V. | Heinzen, Horacio
Calendula officinalis L. (marigold) is a medicinal plant consumed at ton scale worldwide. For that reason the raw material supply cannot rely solely on the collection of wild specimens. C. officinalis is cultivated all over the world not only to cover the increasing demand but also to ensure its regular quality. When conventional cropping systems are employed, the use of pesticides to protect the cultures against pests is a common practice. The presence of contaminants in herbs for medicinal purposes is strictly ruled by Pharmacopoeias. The European pharmacopoeia, as well as the MERCOSUR, require validated methods to determine the content of pesticide residues in each specific medicinal plant. As a contribution to accomplish such requirements, in the present work a comparison of the performance of three modern multirresidue methods based on QuEChERS methodology was conducted. Aiming to find a method fit for that purpose, the original, unbuffered version and variationss of the AOAC 2007.01 and the EN 15662 protocols were evaluated in marigold for the determination of 24 pesticide residues using LC–MS/MS. The three evaluated methods where accurate and precise for all the studied compounds but the original QuEChERS extracts causes less matrix effects over the studied pesticides. After the evaluation of the figures of merits, the selected methodology was validated according to the SANTE guidelines. LOQs were determined in the range 10–100μgkg−1 showing a linear behaviour (r2>0.993) from LOQ to 400μgkg−1. The method was applied in commercial samples where atrazine, imidacloprid, pirimiphos-methyl and methalaxyl residues were detected.
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