Residue determination of cyromazine and its metabolite melamine in chard samples by ion-pair liquid chromatography coupled to electrospray tandem mass spectrometry

• Published in: Analytica chimica acta Vol. 530; no. 2; pp. 237 - 243
• Main Authors: Sancho, J.V., Ibáñez, M., Grimalt, S., Pozo, Ó.J., Hernández, F.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.02.2005; Elsevier
• Subjects: Analytical chemistry; Chemistry; Chromatographic methods and physical methods associated with chromatography; Cyromazine; Exact sciences and technology; Liquid chromatography; Melamine; Other chromatographic methods; Pesticide residues; Spectrometric and optical methods; Tandem mass spectrometry; Vegetables; Tandem mass spectrometry; Liquid chromatography; Vegetables; Pesticide residues; Melamine; Cyromazine; Phosphates; Metabolite; Ion pair; Polar compound; Calibration standards; Chard; Electrospray; Sample preparation; Residue; Detection limit; Mass spectrometry MS/MS; Standard deviation; Quantitative analysis; Methanol
• ISSN: 0003-2670; 1873-4324
• DOI: 10.1016/j.aca.2004.09.038

A method has been developed for the sensitive and selective determination of cyromazine and its metabolite melamine in chard samples. Both compounds are small polar basic molecules, making their determination at residue levels complicated. The method involves an extraction procedure with phosphate buffer and methanol using high-speed blender, the addition of tridecafluoroheptanoic acid (TFHA) as ion-pair reagent and the injection of the five-fold diluted extract on liquid chromatography coupled to electrospray tandem mass spectrometry (LC–ESI–MS/MS). The method has been validated for chard samples, spiked at 0.05 and 0.5 mg kg −1. Quantification was carried out by using matrix-matched standards calibration and recoveries were satisfactory, with mean values for cyromazine of 103% and 93%, and relative standard deviations lower than 7%. In the case of melamine, recoveries were 89% and 86%, with relative standard deviations lower than 13%. A limit of quantification of 0.05 mg kg −1 was obtained for both compounds, with the limit of detection below 0.01 mg kg −1. The method, with very little sample handling and good sensitivity, was applied to the rapid determination of low residue levels of these compounds in chards from field residue trials. All the quality controls included during the analysis were satisfactory with average recoveries of 92% and 78% for cyromazine and melamine, respectively.