Determination Of Residues Of Two Sulfonamides In Milk (hplc) And Its Elimination Of Regular Study

In order to develope a rapid and exact method for determination of residualsulfadiazine(SD) and sulfamonomethoxine(SMM) in milk,a study for the simultaneousdetermination of two sulfonamides including sulfadiazine and sulfamonomethoxine wascarried on by solid-phase extraction and high-performance liquid chromatogyaphy withultraviolet detector.The deplection way of two sulfonamides in milk was studied by thismethod and reasonable withdrawal time was set up.Extraction from samples by experiments: Mearsured 10ml milk sample strictly,transferred to 50ml centrifugal tube,added sodium sulfate 2g and acetonitrile 25ml,mixed15s,shaked in medium rate for 20 min,centrifugalized at 2500r/min for 5 minutes.Transferredupper clear solution to separator, added 30mln-Hexane, shaked for 2 minutes. Stood still for 5minutes. Seprated acetonitrile layer, extract residue with acetonitrile again. Acetonitrile layerwas assigned by the same n-Hexane.Combined acetonitrile layer in 100ml heart bottle,addedpropanol 5ml,concerntrated by low pressure at 50℃to almost dry.Dessloved residude withacetonitrile-water(95:5). The solution was transferred to a C₁₈cartridge column,abandoned.Wash heart bottle with acetonitrile-water (95:5) 5ml, andtransferred to SPEcolumn, blew off the left liquid in the column. Washed away the material to be determinatedto 10ml flask,added water(adjust pH to 4.0 with acid) to 10 ml.Tilterred with 0.45μm filterfilm. Collectted the filtered solution for HPLC assay.The HPLC system consisted of ultraviolet detector and the LCcolumn,ODS-A.Operating conditions were as follows: Flowing phase was water(adjustingpH to 4.0)-acetonitrile (80:20);1.00ml/min flow rate;25℃column temperature;50μlinjection volume; ultraviolet detector set at 270nm.The standard calibration curves showed straight linear curve for SD and SMMbetween0.05μg/ml-1.00μg/ml.The correlation coefficient were 0.99997 for SD and0.99997 for SMM.The detection limits of the method were 10μg/L for SD and SMM. Therecoveries determined for SD ranged from 75%-92% and RSD was 5.74%-6.05%, for SMMrange from 68%-87% and RSD was 3.97%-5.69%.The developed procedure was shown to be applicable for the determination of both SDand SMM in milk. It will provide a sensitive and extract gist for multi-residues determination of sulfonamides. Deplection law of two sulfonamides in milk was studied bythis method, and reasonable withdrawal times were set up(SD is 60h,SMM is 6d), thatagreed to the rules of the nation.