| Food safety is related to with life heath and social stability.The activity of human life depends on the safety and quality of food.Food detection is an important part of food safety management.Sample pretreatment is the first step in food sample analysis,including appropriately separating and enriching target analyte.Meanwhile,the interference of other components in samples also should be eliminated.In this paper,Fe3O4 magnetic nanoparticles were prepared by coprecipitation method,their surface were chemically modified,and a series of magnetic composite materials with core-shell structure were synthesized.The prepared magnetic composite materials were characterized by SEM,TEM and IR.Afterward,the hyphenated techniques of MSPE-HPLC were used to analyze the harmful components in food.The specific researched contents were as followed.(1)A magnetic nanocomposites modified with polystyrene was prepared and characterized by SEM,TEM and IR.It was served as an efficient magnetic sorbent for separation and enrichment of rhodamine B from beverage samples.Afterward,the enriched rhodamine B was determined using HPLC.The factors affecting magnetic solid phase extraction efficiency were optimized.The best adsorption conditions were sorbent 70 mg,time 20 min,pH 4,temperature 35 ?,and sample volume 250 mL;the best elution conditions were methanol volume 2.5 mL,pH 8,temperature 20 ?,and time 5 min.Under optimized conditions,the enrichment factor of rhodamine B was 100,and the calibration curve was linear at a concentration range of 1-250 ?g/L.The limit of detection was 0.0021 ?g/mL(three times S/N),the limit of quantification was 0.0035 ?g/mL(five times S/N),the relative standard deviation was 0.87(n=11),and the recoveries were 95.2%-103.6%.In terms of the proposed procedure,the developed method was successfully applied for rhodamine B detection in beverage samples.(2)A magnetic nanocomposites modified with laccaic acid was prepared and characterized by SEM and IR.It was served as an efficient magnetic sorbent for separation and enrichment of tetracyclines from bovine milk samples.Afterward,the enriched tetracyclines were determined using HPLC.The factors affecting magnetic solid phase extraction efficiency were optimized.The best adsorption conditions were sorbent 80 mg,time 20 min,pH 7,temperature 45 ?,and sample volume 50 mL;the best elution conditions were acetonitrile volume 0.5 mL,pH 5.5,temperature 75 ?,and time 5 min.Under optimized conditions,the enrichment factor of tetracyclines was 100.The calibration curves were linear at a concentration range of 10-300 ?g/kg for oxytetracycline and tetracycline and 5-300 ?g/kg for chlortetracycline and doxycycline.The limit of detection was from 3.2 to 7.1 ?g/kg(three times S/N),the limit of quantification was from 10.7 to 23.7 ?g/kg(ten times S/N),the relative standard deviation was between 2.8 and 5.3(n=5),and the recoveries were 95.2%-106.2%.In terms of the proposed procedure,the developed method was successfully applied for tetracyclines detection in bovine milk samples.(3)A magnetic nanocomposites modified with benzofuran-2-carboxylic acid was prepared and characterized by SEM,TEM and IR.It was served as an efficient magnetic sorbent for separation and enrichment of patulin from apple juice samples.Afterward,the enriched patulin was determined using HPLC.The factors affecting magnetic solid phase extraction efficiency were optimized.The best adsorption conditions were sorbent 40 mg,time 25 min,pH 5,ambient temperature,and sample volume 50 mL;the best elution conditions were methanol volume 0.5 mL,pH 5,ambient temperature,and time 4 min.Under optimized conditions,enrichment factor was 100,linearity range was 1-400 ?g/L of patulin,limit of detection was 0.15 ?g/L(three times S/N),and limit of quantification was 0.5 ?g/L(ten times S/N).The relative standard deviation was below 5.3%(n=20)and the recoveries were 93.9%-102.6%.In terms of proposed procedure,the developed method was successfully applied for patulin detection in apple juice samples.(4)A magnetic nanocomposites modified with graphene was prepared and characterized by SEM,TEM and IR.It was served as an efficient magnetic sorbent for separation and enrichment of Allura Red in food samples.Afterward,the enriched Allura Red was determined using HPLC.The factors affecting magnetic solid phase extraction efficiency were optimized.The best adsorption conditions were sorbent 40 mg,time 15 min,pH 3,temperature 35 ?,and sample volume 200 mL;the best elution conditions were methanol volume 1 mL,pH 6,temperature 55 ?,and time 5 min.Under optimized conditions,the enrichment factor of Allura Red was 200,and the calibration curve was linear at a concentration range of 5-1500 ?g/kg.The limit of detection was 2 ?g/kg(three times S/N),the limit of quantification was 7 ?g/kg(ten times S/N),the relative standard deviation was 3.3%(n=11),and the recoveries were.98.8%-100.6%.The proposed MSPE procedure was simple and fast,and it was successfully applied for Allura Red determination of food samples.(5)A magnetic nanocomposites modified with chitosan was prepared and characterized by SEM,TEM and IR.It was served as an efficient magnetic sorbent for separation and enrichment of pyrethroids from drinking water samples.Afterward,the enriched pyrethroids were determined using HPLC.The factors affecting magnetic solid phase extraction efficiency were optimized.The best adsorption conditions were sorbent 40 mg,time 5 min,pH 7,temperature 35 ?,and sample volume 50 mL;the best elution conditions were acetonitrile volume 0.5 mL,pH 5.5,temperature 25 ?,and time 3 min.Under optimized conditions,the enrichment factor of pyrethroids was 100.The calibration curves were linear at a concentration range of 0.1-400 ?g/L for four studied pyrethroids.The limit of detection was from 0.02 to 0.16 ?g/L(three times S/N),the limit of quantification was from 0.07 to 0.53 ?g/L(ten times S/N),the relative standard deviation was between 1.6% and 2.4%(n=7),and the recoveries were 92.2%-103.2%.In terms of the proposed procedure,the developed method was successfully applied for pyrethroids detection in drinking water samples. |
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