| With the rapid development of Chinese food processing industry, food safety becomes aevent of the national economy and people’s livehood. There are many factors affecting on the foodsafety, and among them the application of lubricating oils in the food processing industry is themost one. The industrial lubricating oils may contain hazardous substance such as polycyclicaromatic hydrocarbons (PAHs), annexing agent etc. Once leaked, it would contaminate the food,drink and so on, and may result in food safety event.Compared with the registration and certification supervision system of food-grade lubricatingoils by international developed countries, our country is lack of this system. According to thenational sanitation foundation (NSF),“the proprietary substance and nonfood compoundsregistration guide”, it makes clear regulation that food-grade lubricating oils cannot containanyimony, arsenic, cadmium, lead, mercury, selenium, six kinds of poisonous and hamful traceelements, carcinogenic substance, water-soluble inorganic acid, and odorous organic compounds.In order to solve the problems of residuals in food-grade lubricating oils shown in above, fourmain research contents are included in this paper shown as follows.1. The method of gas chromatography-mass spectrometry (GC-MS) for measuring16polycyclicaromatic hydrocarbons (PAHs) of prior control by EPA in food-grade lubricating oils wasestablished. The sample was solved in cyclohexane and extracted by dimethyl sulphoxide whichwas saturated by cyclohexane, and then back extracted by cyclohexane and NaCl solution,purified by solid phase extraction column. The purified sample was analyzed qualitatively andquantitatively by GC/MS with SIM mode. The limit of detection (LOD) of PAHs in food-grade lubricating oils was0.01~0.05mg/kg, and the limit of quantitation (LOQ) was0.03~0.16mg/kg.The average recoveries of PAHs were80.9%~109.5%, and the relative standard deviations (RSD,n=6) were between2.4%~4.9%. It was showed that this method was suitable for simultaneouslydetecting16PAHs in food-grade lubricating oils.2. Adopted a method of microwave digestion pretreating technique, an analytical method usinginductively coupled plasma mass spectrometry (ICP-MS) for the determination of trace As, Se, Cd,Sb, Hg, Pb elements in food-grade lubricating oils was established. Through optimizing the testingcondition, the samples of food-grade lubricating oils were detected, and the limits of detection(LOD) of all the elements was in the range from0.001~0.020mg/kg, The average recoveries were93.3%~116.0%, and the relative standard deviations (RSD, n=6) were between2.1%~5.6%.These results showed that this method had the advantage of easy-handle, high sensitivity and goodreproducibility, and was demonstrated to be suitable for quantitative testing of trace toxic andharmful elements in food-grade lubricating oils.3. An ion chromatography (IC) with suppressed conductance detection was developed for thesimultaneous determination of Cl-, NO-, SO2-34in food-grade lubricating oils. After ultrasonicextraction with50%(v/v) methanol aqueous solution and centrifugation，the sample in aqueousphase was purified with0.22μm hybrid fiber membranes, then analyzed by IC using15mmol/LKOH solution as eluent，and detected by a suppressed conductance detector. Under the optimizedseparation conditions, the limits of detection (LOD) were0.01~0.03mg/kg. The averagerecoveries of Cl-, NO3-, SO42-anions were90.0%-103.6%with the relative standard deviations(RSD, n=6) of2.8%~5.7%. This method could determine the amounts of three inorganic anions(Cl-, NO3-, SO42-) in food-grade lubricating oils fast and accurately. It was suitable forsimultaneously separating and detecting trace inorganic anions in lubricating oils.4. An analytical method to determine benzene, toluene, chlorobenzene, p-xylene, o-xylene andalpha methyl styrene in food-grade lubricating oils by headspace gas chromatography massspectrometry (GC/MS) was presented. Results indicated that the limit of detection of the methodwas0.01~0.05mg/kg and the recovery was83.5%~106.1%with relative standard deviation(RSD, n=6) between1.1%~9.7%. The method was rapid, accurate and suitable for the analysis ofbenzene compounds in food-grade lubricating oils. |
PDF Full Text Request