Simultaneous analysis of 21 sulfonamides, trimethoprim, ormetoprim, and dapsone in fish and shrimp samples by LC-MS/MS using the QuEChERS method

Antibiotics and antibacterials, including sulfonamides, are components of the veterinary armamentarium used to prevent and treat diseases in seafood. However, the accumulation of veterinary drug residues in seafood can cause food safety concerns. This study aimed to verify the quantitative analytical method for sulfonamides, trimethoprim, ormetoprim, and dapsone in seafood and to apply it to fish and shrimp distributed in Korean market. In the present study, three types of matrices (shrimp, flatfish, and eels) were used to detect drugs (n = 25) (sulfonamides (n = 21), trimethoprim, ormetoprim, dapsone, and monoacetyldapsone). Matrices were extracted with acetonitrile and mixed with 2 g of magnesium sulfate and 1 g of sodium acetate. After agitation, supernatants were mixed with 300 mg of C18 and centrifuged again. Then the supernatant was evaporated, dissolved in 50% methanol, and filtered through a PTFE filter. Extracts (5 mu l) were then injected into the liquid chromatography-tandem mass spectrometry system. The method was validated in terms of limit of detection, limit of quantitation, decision limit, decision capability, matrix effects, intra/inter-day accuracies, precisions, and stabilities and the method was applied to fish and shrimp sold in the Korean market. The validation results were found to be satisfactory. As a result of applying the validated method to fish and shrimp samples purchased from the Korean market, sulfacetamide, sulfadimethoxine, sulfamethoxazole, and sulfanilamide were detected in shrimp samples. The devised method for analysing antibiotics in seafood samples enables antibiotic detection in fish samples distributed in the global market and should aid the adoption of preventative measures.