Influence Of Dispersive Solid Phase Extraction Pretreatment On Determination Of Chloramphenicol Residues In Milk And Yogurt

Chloramphenicol accumulates in food-borne animals,and then enters the human body through the food chain,which will bring greater safety risks to human life and health.Therefore,it is extremely important to establish an efficient,convenient and sensitive detection method for chloramphenicol.At present,In"GB29688-2013 Determination of Chloramphenicol Residues in Milk by Liquid Chromatography-Tandem Mass Spectrometry",solid phase extraction（SPE）is used to pre-treat chloramphenicol,which requires extraction column activation,sample loading,elution,etc.,which is not suitable for batch processing.This topic uses dispersive solid phase extraction technology to optimize the process of extracting and purifying chloramphenicol in milk and yogurt,which further expands the application scope of Qu ECh ERS technology.In this experiment,acetonitrile was used for the extraction process,and chloramphenicol in milk and yogurt samples was extracted by adding2g Mg SO₄and 0.5g Na Cl.The sample was further purified by 200mg C₁₈and 600mg anhydrous magnesium sulfate.The ultra-high performance liquid phase tandem mass spectrometer produced by SCIEX of the United States was used at a column temperature of 40°C,a mobile phase flow rate set at 0.3m L/min,and acetonitrile+water（30+70,v/v）solution is eluted by isocratic elution.The CAP residues in milk and yogurt are determined qualitatively and quantitatively by using electrospray mode and negative ion scanning.In the range of 0.05～5μg/L,the linear relationship of the detection method is good,which meets the requirements of relevant national standards.The correlation coefficient r is 0.99533,and the regression equation is:Y=5.11401X+0.77957.In the concentration range of0.1～1μg/kg,the REC of the milk sample was 87.53%～98.66%,and the REC of the yogurt sample was 89.36%～102.56%.In this method,the LOD of chloramphenicol in milk samples is 5ng/kg,and the LOQ is 25ng/kg.The LOD of chloramphenicol in the yogurt sample is 7ng/kg,and the LOQ is 25ng/kg.The intra-day and inter-day RSD values of this method in milk samples were 1.46%～7.52%and 3.16%～7.1%,respectively,and the intra-day and inter-day RSD values of yogurt samples were 1.65%～6.58%and 2.04%～7.95.Both are less than 10%,in accordance with the national standard testing standards,within the acceptable range.The intermediate solution of the standard chloramphenicol has good stability in a refrigerator at 4°C and can be stored for at least 5 months.Using the method for the detection of chloramphenicol residues in milk and yogurt established in this experiment,15 different brands and fat content milk and 10 yogurt samples purchased from local supermarkets and stores in Zhangjiakou City,Hebei Province were tested,and no chloramphenicol was found.Residue.The establishment of this method further reduces the detection limit of chloramphenicol.If you want to further reduce the detection limit of this method,you can choose a chromatographic column with smaller filler particles and higher column efficiency.