Sensitive spectrofluorimetric methods for determination of ethopabate and amprolium hydrochloride in chicken plasma and their residues in food samples

•Synchronous spectrofluorimetric methods are used to determine the studied drugs.•Successful application in different food samples and chicken plasma.•The proposed methods can be used in food QC without the difficulties of HPLC.•The proposed work simplifies the extraction and clean-up processes.•The proposed methods are validated according to ICH guidelines.

Two sensitive and selective spectrofluorimetric methods are proposed to determine ethopabate (ETH) and amprolium hydrochloride (AMP). First derivative synchronous spectrofluorimetry determines the natively fluorescent ethopabate at 288 nm in presence of amprolium hydrochloride which is a non fluorescent quaternary compound with average recovery 100.54 ± 0.721 over a concentration range of 0.01–0.8 μg/mL. Limits of detection (LOD) and quantification (LOQ) are 0.002 and 0.007 μg/mL, respectively. The second method is direct synchronous spectrofluorimetry for determining amprolium hydrochloride at 362 nm after a reaction with 5% NaOH and 0.08% potassium ferricyanide that is optimized by a two-level factorial design. This method is linear over a concentration range of 0.01–0.65 μg/mL with average recovery 99.4 ± 1.28. Limits of detection (LOD) and quantification (LOQ) are 0.002 and 0.006 μg/mL, respectively. The proposed methods are found to be valid and applicable for the analysis of ETH and AMP in their veterinary formulation. They are successfully applied to determine the studied drugs in chicken plasma and their residues in chicken muscle, liver, egg and chicken-based baby food product with recoveries in the ranges of 95.71–108.73% and 97.36–111.89% and for ETH and AMP, respectively.

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