Determination Of Trace Sulfonamides Residues In Animal Food

Residues of veterinary drugs in animal food have become the worldwide testing focus for the existence of the public health hazard. Sulfonamides have been widely used in China. It may result in meat, milk and animal tissue residues when sulfonamides used in animal disease prevention and treatment. To ensure the safety of people's diet, the establishment of an effective method to detect sulfonamides veterinary drug residue in animal food have important practical significance. The tubular structure of carbon nanotubes exist both inside and outside surface so that it will have a larger surface area, which make carbon nanotubes have a great potential for the effective solid-phase extraction of certain compounds. In this study, a method of using multiwalled carbon nanotubes as sorbent, coupled to high-performance liquid chromatographic-ultraviolet detector (HPLC-UV) to detect 10 SAs residues in animal food was developed. Some important factors that influenced 10 SAs preconcentration, elution and determination were discussed in detail. These factors include the pH of the sample loading solution, the flow rates of the sample loading solution, the volume of the sample loading solution, choice of a suitable eluent, the volume of the eluent, choice of a mobile phase and the proportion of mobile phase for the baseline separation of the 10 SAs. The results indicated that, for 1μg L^-1 10 SAs, the optimal pH of the sample loading solution was chose 4.5, the flow rates and volume of the sample loading solution was 5mL min^-1 and 100 mL, respectively, 5 mL methanol was selected to ensure the complete stripping of the adsorbed 10 SAs from the multiwalled carbon nanotubes, water : methanol = 78 : 22 was employed as eluent to achieve the baseline separation of 10 SAs. Under optimum conditions the peak areas were linear between 0.2^-15μg L^-1 with r2 > 0.99, and the detection limits (3N) of 10 SAs were in the range of 2.1-9.3 ng L^-1. To evaluate the accuracy of the developed multiwalled carbon nanotubes solid-phase extraction coupled with HPLC-UV for the determination of trace 10 SAs, the real milk and pork sample which was free SAs were analyzed. The recovery of spiked real samples which were spiked at two levels (5 and 10μg kg^-1) were in the range of 70.18-84.68%, and RSD ranged in 1.02-9.92%. The research results presented here will provide technique reference for the determination of trace residues of veterinary drugs in animal food.