| As a new sample pr etreatment technique, the liquid phase mic r oextracti on(LPME) has features of easy opera tion and has little influence on the health of operat or and envi ronment, whi ch meets the environmentally-friendly conc ept. The LPME tec hnology has a variety of extraction modes, the selection of it base d on the sample’s matrixes and the nat ure of target, which have good enrichment and purification ability. So far, the LPME technology continues changing and i nnovati ng no matter in fields of pesticide residue s,food a dditivies or toxic i ngredients ’ detection in food packing materials. Due t o t hese aspects r ela ted to our human life, the harm of food safety may ar ouse more our attention.Thi s study discussed the method of hollow fiber( HF) liquid phas e microextraction,s eperately pretreated the dimethoa te in lemon, the sorbic acid in dri nk and bisphe nol A(BPA) in compl ex samples such as milk in differ ent packing and shopping rec eipt s.Combing this me thod with high performa nce liquid chromatography(HPLC) to detect and ana lyse their content, specified works are a s follows:1. Usi ng the pr etreatment technology of two-phase HF-LPME combined with HPLC to detect the di methoate. By optimi zing t he LPME paramete rs of extraction age nt,ext ract ion te mperature, e xtrac tion time, s tirring speed and salt concentration, the enrichment ratio of dimethoat e wa s obtained and the optimum conditions were det ermined:us ing tributyl phosphate(TBP) as extractant, extraction temperature was 40℃, extraction time was 20 min, stirring spee d was 500 r/min and no sal t(NaCl). The linear equation was Y=18.177X+2.3587, the correlation coefficient was 0.9997, the relative standard deviation(RSD) was 3.1%, the l imit of de tection(LOD) was 1.86 μg/L, t he enric hment ratio of dimethoate reache d to 35~108 times a nd the average recoveries rate were withi n the range of 84.0%~91.8%.2. Using the pretreatme nt technology of three-phase HF-LPME combined with HPLCt o detect the s orbic acid. By opt imizing the LPME paramet ers of organic ext ract ion agent,t he pH of re ceiver phase and provider phase, extraction temperature, extraction time,stir ring speed and salt concentration, t he enrichment ratio of sorbic acid was obtained and t he optimum conditions were determined: using TBP as extractant, the pH of r eceiver pha se wa s 13 a nd provi der phase was 2.5, extraction temperature was 35℃, extraction time was 30 min, stirring speed was 600 r/ min and the salt concentration was 5.0 g/L.The linear e quati on was Y=1.5592+1254.6X, the correlation coefficient was 0.9999, the relative standard deviation( RSD) was 2.3%, the limit of dete cti on(LOD) was 0.345 μg/L, the e nr ichment r ati o of dimethoa te reached to 452~497 times and the average rec overies rate were within the r ange of 83.0~93.0%.3. Using the pretreatment t echnology of two-phase HF- LPME combi ned with HPLC t o det ect the BPA. By optimi zing the LPME paramet ers of e xtrac tion agent, the pH of sample solution, e xtraction temperature, ext ract ion time, stirring speed and the c oncentr ati on of NaCl, the enrichme nt ratio of B PA was obt aine d and the optimum c onditi ons were det ermined: using n-octyl alc ohol as extractant, the pH of sample solution was 6.2, ext ract ion temperat ure was 40℃, e xtrac tion time was 40 mi n, stir ring speed was500 r/mi n and no salt.The l inear equation was Y=590.03X+39.98, the correlation c oefficient was 0.9997, the relative st andard deviation(RSD) wa s 1.2%, the limit of de tection(LOD) was 3.6 μg/L, the enric hment ratio of di met hoate reached t o 207~274t imes and the average recoveries rate were within the range of 87.5~93.0 %. |
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