| PCBs is a typical persistent pollutants in environment, which has properties ofpersistance, highly accumulation, highly toxicity and long-range mobility. PCBs canwidely distribute in the environment, with the food chain progressively enriched inorganism. PCBs also has three-induced toxicity. Due to it has potential threats tohuman health, so it becomes a hot research field of environment and food. ThePCBs in marine products belong to the the detection of trace multicomponent, so thesample pretreatment technology is important to the veracity and reliability of analysisresult. Analytical procedures for detecting PCBs from marine samples include Soxhletextraction, microwave-assisted extraction, these methods require long extraction timesand consume large quantities of hazardous organic solvents. Supercritical fluidextraction (SFE) technology has become an increasingly popular method because ithas the advantages of a shorter extraction time and lower organic solvent consumption.But it needs high operating pressure so the equipment hard to promote. Taking intoaccount economic and environmental concerns, subcritical fluid extraction canovercome the shortcomings of supercritical fluid extraction, which can achieve betterextraction efficiency under relatively low pressure. So it has drawn more and moreattention.1,1,1,2-Tetrafluoroethane (R134a) is non-toxic and non-flammable, andreasonable critical properties (101C,40.6atm). These characteristics led to thesuperiority of its use as an alternative to supercritical CO2for the extraction. It isessential to establish a reliable, fast, convenient and green analytical method to detectPCBs in aquatic products. The purpose of this paper is to develop a subcritical R134aextraction-gas chromatohgraphy-mass spectrum method for the determination ofPCBs in aquatic products, this new method is reliable, green, quic. This new methodis applied to the detection of PCBs in reality sample.This article used subcritical R134a extraction as a pretreatment technology,selected7kinds of PCBs as object of study, single factor and response surfacemethodology (RSM) were adopted to investigate the influence of extraction pressure,extraction temperature, extraction time, and co-solvent volume. The results show that, with the subcritical R134a extraction condition, extraction temperature31℃,extraction pressure6MPa, co-solvent volume of methanol is7mL, static extraction20min, dynamic extraction time40min, flow of R134a is10g/min, mean recoveriesof seven PCBs were above90%, RSD were at less than5%. In this condition, themethod detection limit of dry weight is0.045-0.108ng/g. The response surface modelshows, extraction temperature and the volume of the co-solvent have a significanteffect on the recoveries of total PCBs, but the extraction pressure have on significanteffect on the recoveries of total PCBs. The interactions of all factors are significant.Compared with traditional soxhlet extraction, ultrasonic extraction methods,subcritical R134a extraction has the advantage of fast, green, efficient in theextraction of PCBs.This paper also studys the purification process of subcritical R134a extractionsolution. In this study online purification and offline purification were researched. Theeffect of neutral alumina, silicon magnesium adsorbent, silica gel, acidified silica gelused as online purification is not good. Concentrated sulfuric acid and silica gelcolumn purification method meet the testing requirements among these methods,recoveries of these two methods were91.9%-102.3%and87.7%-98.1%,respectively. RSD were less than8%, the results of experiments show that these twomethods can remove the impurities in the extract effectively, and have good recoveryand stability.Finally, this study has used the established method of subcritical R134a extractionand off-line purification to detect PCBs in seafood to test the effectiveness andapplicability of the new method. For provide the more scientific basis, this studysimulated the in vitro digestive environment to investigate effectiveness andapplicability of the PCBs in seafood through the process of body intake. The resultsshowed that there were6kinds of PCBs have been detected except PCB180in aquaticproducts, these are PCB118, PCB101, PCB28, PCB153, PCB52in order of thedetectable amount; PCBs in human digestion is1.71%-5.83%.The analysis of PCBs in marine products is a technology to analysis the trace,ultra trace multicomponent residues in complex matrix biological samples. This studythrough detect the level of PCBs in local breast milk to analyze the kinds and amountsof PCBs in bodies of local human to broaden the applicability of this newpretreatment method and tset the practicality of this new method as a pretreatmenttechnology to analysis the trace, ultra trace, multicomponent residues in complex matrix biological samples. The results showed, there was only PCB118be detected inbreast milk, this result is consistent with the results of the actual sample testing(PCB118has the highest concentration) and the historical usage of PCBs in ourcountry (give priority to trichlorodiphenyl and pentachlorodiphenyl).This paper established a new method to analysis the residue of PCBs in marineproducts by subcritical R134a extraction and off-line purification. This method isquick, accuracy, green and efficient. And after further research and application, it maybecome a new sample pretreatment technology to analysis the trace, ultra tracemulticomponent residues in complex matrix biological samples. |
PDF Full Text Request