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Abstract
Issue Title: Carbon nanotubes for solventless in-tube microextraction/Chemical composition separation of ethylene-propylene copolymers/Mass calibration for direct analysis in real-time mass spectrometry/Quantitative Ca2+ imaging in living cells
Avilamycin residue in food is regulated as its marker residue dichloroisoeverninic acid (DIA). An isotope dilution liquid chromatography-tandem mass spectrometry method is established for the accurate determination of DIA in animal muscles without any pre-extraction and preconcentration prior to alkaline hydrolysis. Optimization of the sample cleanup procedures such as liquid-liquid extraction and solid phase extraction was performed by fine-tuning several critical parameters to reduce the matrix effects. Quantification of DIA in edible muscle was accomplished by using matrix-matched calibration with dichloroisoeverninic acid-d^sub 6^ as internal standard. The method was validated with DIA and avilamycin-fortified poultry and porcine muscles at three different levels (25, 50, and 100 [mu]g/kg). Conversion of avilamycin to DIA by alkaline hydrolysis was ≥92 %. The recoveries of DIA in both muscles at three fortification levels ranged from 94 to 106 % and RSDs were ≤11 % in all cases. The estimated limit of detection values in poultry and porcine muscles were 2.7 and 0.7 [mu]g/kg, respectively. The estimated limit of quantitation values in poultry and porcine muscles were 8.3 and 2.4 [mu]g/kg, respectively. This method is suitable for routine monitoring of avilamycin residue in food safety surveillance programs.