Verification Of Detection Capability On Residues Of Sulfonamides And Trimethylbenzene Veterinary Drugs In Freshwater Fish

The Shanghai Institute of Metrology and Measurement Technology(SIMT)recently launched a project for the “Determination of Sulfonamides and Malachite Green Residues in Aquatic Products” in order to investigate the ability of the laboratory of Shanghai Qualification Accreditation Inspection and Testing Institution on carrying out the total amount of sulfonamide and trimethylbenzene veterinary drug residue testing,and at the same time to master experimental differences and strengthen laboratory capacity building in Shanghai’s key areas.All the laboratories involved the project are voluntary and organized by the Shanghai Municipal Bureau of Quality and Technical Supervision.The Shanghai Institute of Metrology and Testing Technology is responsible for the coordination and implementation.Our research is an important part of the project,which mainly contains the verification of the detection ability of sulfa and trimethylbenzene veterinary drug residues in freshwater fish aquatic products.The purpose of the project is: 1)to conduct statistical analysis and technical analysis of the results of proficiency testing;2)to conduct in-depth research and discussion on the problems existing in the existing detection methods;3)to optimize the experimental conditions that affect the test accuracy;4)finally determine the best detection method.The samples for proficiency testing in this paper were obtained by using the “segmentation level” sample design according to standard substance preparation methods.The proficiency test results were evaluated using the median value robust statistical method.The specific contents of this paper include: 1)using single-factor analysis of variance method for homogeneity testing;2)t-test method for assessing the stability of the sample;3)optimizing the conditional parameters such as column chromatography method,derivatization method,and separation and analysis of LC/MS;4)Finally,validating and refining the analysis and evaluation of the large amount of data collected by the proficiency testing activities.The conclusions are as below:(1)Limit of detection(LOD)of sulfa Drug Residue is no more than 0.3 μg/kg.Limit of Quantitation(LOQ)of sulfa Drug Residue is no more than 1.0 μg/kg.And the linear regression coefficient R2 of each sulfonamides is no less than 0.994 in the range of 10-200 μg/kg.At the three concentration levels of 10,50,and 200 μg/kg,the spike recovery is no less than 88.6% and the relative standard deviation is no more than 3.6%.(2)Limit of detection(LOD)of malachite green drug residue is no more than 0.2 μg/kg.Limit of quantification(LOQ)of malachite green drug residue is no more than 0.5 μg/kg.And the linear regression coefficient R2 of malachite green and leucomalachite green is no less than 0.999 in the range of 1-20 μg/kg.At the three concentration levels of 1,5,and 20 μg/kg,the spike recovery is no less than 88.5% and the relative standard deviation is no more than 2.6%.(3)The samples in the proficiency test exhibit enough homogeneity and stability to guarantee proficiency testing within the specified time.Participating laboratories posses the ability to obtain good enough detection data.However,there still appear some suspicious or unsatisfactory results.The main reasons of deviations in the detection are differences in detection methods,incomplete extraction of pre-treatments,and improper quality control of detection links.