engleski

Validation of a multi-residue enzyme-linked immunosorbent assay for qualitative screening of corticosteroids in liver, urine, and milk

A rapid and sensitive enzyme-linked immunosorbent assay (ELISA) has been applied for the qualitative screening analysis of dexamethasone, betamethasone, flumethasone and prednisolone in liver, milk and urine samples at levels corresponding to the European Union (EU) maximum residue limit (MRL), or at required performance levels (RPLs) for substances for which there is no established MRL value. Method validation was performed according to Commission Decision 2002/657/EC criteria established for qualitative screening methods. In this regard, the following parameters were determined: detection capability (CCβ), specificity, detection limit (LOD), quantitation limit (LOQ), recovery, within-laboratory reproducibility, linearity and ruggedness. LOD values were 0.18 μg kg-1, 1.18 μg kg-1 and 0.65 μg kg-1 in milk, urine and liver samples, and LOQ values were 0.34 μg kg-1, 1.18 μg kg-1 and 1.39 μg kg-1 in milk, urine and liver, respectively. The recoveries from spiked samples ranged from 67.9–130.7% for dexamethasone, 56.7–119.6% for flumethasone, 60.4–154.9% for betamethasone and 22.7–31.9% for prednisolone, with a coefficient of variation (CV) between 1.6–21.2%. The CCβ value resulted below the MRL/RPL for all examined matrices. Moderate variations of some critical factors in the sample pre-treatment for liver and milk samples were deliberately introduced for ruggedness evaluation and did not result in any negative effects on corticosteroid detection. The proposed method is suitable for qualitative screening analysis of corticosteroids in the above-mentioned food in conformity with the current EU performance requirements.

corticosteroids; liver; milk; urine; enzyme-linked immunosorbent assay

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