| Trace toxic components in food and drug is an important parameter to evaluate the quality,and it is also an important issue to protect the people’s health and safety.There are many kinds of modern drugs and food,the compositions are complex,the content of residual toxic components is very low.Therefore,in the analysis of trace components in complex samples,the effective sample pretreatment technique is an essential step.Along with the development of more and more high sensitivity analysis instruments,for the analysis of trace toxic components in complex samples,the traditional sample pretreatment is difficult to meet the requirements of quantitative analysis.Combining with an appropriate sample pretreatment method,to purify samples,separate and enrich the trace elements from the matrix,is a key step in the quantitative analysis and also one of the hot spots in th whole analysis area.Part 1 Contamination and detection of metal residues in drug1 Determination of residual palladium in drug by direct injection-GFAASObjective: A direct injection GFAAS method was established to determine the palladium in drug.The parameters of graphite furnace and the solvent were investigated systematically.The results were compared with the microwave digestion method.A simple and reliable analytical method was established for the determination of residual palladium in drug.Method: With Tofacitinib,Bazedoxifene Acetate and Apremilast as model drug,the residual amount of palladium in drugs was determined by direct injection and microwave digestion combined with GFAAS.The effect of dry,ash temperature and solvent on the residue analysis of palladium were investigated.Tofacitinib,Bazedoxifene Acetate and Apremilast were dissolved in 1% HNO3,ethanol and THF solution respectively.In the optimization of thegraphite furnace temperature program,sample solutions were determined directly by GFAAS.Results: After the drugs were dissolved in the appropriate solvents respectively,under the optimized experimental conditions,the proposed method was accurate,and no great disturbance background.The LOQ was2.35-4.95 ng/mL,LOD was 0.71-1.49 ng/mL.The average recoveries were99.5-99.8 % with RSD 0.8-2.3%.The results of proposed method were greater than the microwave digestion method,because of too many operation steps over the microwave digestion method,resulting in the loss of palladium.Conclusion: This paper studied the sample pretreatment method in residual palladium analysis.After selecting a appropriate solvent without the complex microwave digestion steps,the sample solutions were able to determine by GFAAS directly.The effect of dry and ash temperature of graphite furnace procedure as well as solvents on the residual palladium analysis were studied systematically.Under the optimized experimental conditions,the results of proposed method were accurate and reliable.There were no significant background interference.It simplify the complex operation steps of traditional pretreatment,and reduced the errors caused by excessive operation.2 MAE-GFAAS for the determination of residual aluminum ion in Huoxiang zhengqi pelletsObjective: To establish a microwave-assisted extraction method combining with GFAAS method for the determination of residual aluminum ion in Huoxiang zhengqi pellets.The sample pretreatment method was systematically investigated.The residual aluminum ion in samples was extracted by EDTA solution.The microwave extraction conditions and graphite furnace temperature program were investigated,to provide a rapid detection method for residual aluminum analysis in Chinese traditional medicine.Method: With Huoxiang zhengqi pellets as model drug,the aluminum ion in samples was extracted by EDTA solution.0.1 g sample was added in 20 mL 0.05 mol·L-1 EDTA solution(pH=3.5),followed by the microwave extraction(150℃,10 min).The detection wavelength was 257.4 nm.Under the optimized experimental conditions,the sample solution was determined by GFAAS.Results: After the aluminum ion in Huoxiang zhengqi pellets was extracted by EDTA solution,the sample solution was determined by GFAAS.Under the optimized microwave extraction conditions and graphite furnace temperature program,the LOQ was 7.89 ng·mL-1,and LOD was 2.37 ng·mL-1.The average recovery was 96.9%~101.2% with RSD less than 2.3%.Conclusion: A microwave-assisted extraction method combining with GFAAS method was proposed for the analysis of residual aluminum ion in Huoxiang zhengqi pellets.It simplify the complex operation steps of traditional pretreatment,and no significant background interference.The analysis results were accurate and reliable.It provided a rapid detection method for residual aluminum analysis in Chinese traditional medicine.Part 2 Novel sample pretreatment method for the determination of Aflatoxin B1,B2,G1 and G2 in milk sampleObjective: A novel sample pretreatment method based on graphite oxide stir bar sorptive extraction was established for the separation and enrichment of trace AFB1,AFB2,AFG1,AFG2 in milk sample.The AFs were determined by HPLC-FLD with post-column derivatization.To provide a reference method for the separation,enrichment and detection of trace aflatoxins in milk.Method: With commercial milk as sample,the coated graphite oxide stir bar was put into sample solution,followed by the SBSE procedure(45℃,20 min).Finally,the aflatoxins desorbed by methanol were analyzed by HPLC-FLD directly.Analysis was performed on phenomenex C18 column(250×4.60 mm,5 μm),eluted with MeOH-MeCN-Phosphoric acid aqueous solution(pH=3.5)(3:3:5,v/v).The flow rate was 0.8 mL·min-1.The post-column derivatization reagent was 0.05% iodine solution with flow rate0.3 mL·min-1 and reaction temperature 70℃.The excitation wavelength was360 nm,and emission wavelength was 450 nm.Results: A good extraction efficiency of aflatoxins was achieved by the self-made synthesized graphene oxide stir bar with enrichment factor 8-24.The proposed method can be used for the quantitative analysis of aflatoxins in milk sample.Under the optimized extraction conditions,good linear relationships were obtained with the linear of AFB1 and AFG1 0.100-2.00ng·mL-1,AFB2 and AFG2 0.050-0.500 ng·mL-1,respectively.The recoveries were 81.9-98.4% with RSD less than 3.4%.The LODs were 0.015-0.03ng·mL-1,LOQs were 0.05-0.1 ng·mL-1.Conclusion: The proposed method is simple,high sensitivity,strong tolerance and good specificity,which can provide a simple and reliable means for the separation,enrichment and detection of trace aflatoxins in milk samples. |
