Study And Application Of The Method For Detecting Phthalic Acid Esters In Seawater By Stir Bar Sorptive Extraction-Gas Chromatograph-Mass Spectrograph

In recent years, with the rapid development of plasticizer industry, the phthalic acid esters have been widely used. PAEs are a kind of endocrine disruptors, the function is like the type of estrogen, would pose a serious threat to plants, animals and human body. PAEs were always used as additive in plastic. As PAEs are combined plastic polymer with inter-atomic forces, such as hydrogen bonds and van der Waals force, without the stable chemical bonds, the PAEs and the plastic polymer still have its own physicochemical properties. When the client environment changed and the time of using plastic went on, the PAEs would separate out from the plastic polymer. Then they migrate to the environment. The PAEs have been detected in almost all kinds of environmental sample, for instance, the atmosphere, water, soil, sediment, etc. The PAEs plasticizers have become ubiquitous contaminant the world.In this paper,15 kinds of PAEs were select as target materials. They were dimethyl phthalate (DMP), diethyl phthalate (DEP), diisobutyl phthalate (DiBP), dibutyl phthalate (DnBP), di(2-methoxyethyl)phthalate (DMEP), di(4-methyl-2-pentyl) phthalate (DMPP), di(2-ethoxyethyl) phthalate (DEEP), di-n-pentyl phthalate (DPeP), di-n-hexyl phthalate (DHP), butyl benzyl phthalate(BBzP), di(2-n-Butoxyethyl) phthalate(DBEP), dicyclohexyl phthalate (DCHP),di(2-Ethylhexyl) phthalate (DEHP), diphenyl phthalate (DPhP), di-n-octyl phthalate (DOP). To measure the PAEs content in the seawater, the stir bar sorptive extraction-gas chromatography-mass spectrometry (SBSE-GC-MS) were established. In the progress of extraction, the factors affecting extraction and desorption were optimized. The factors affecting extraction were extraction time, extraction temperature, the amount of methanol and NaCl addition. The factors affecting desorption were major desorption solvent and desorption time. The linear range, limit of detection, accuracy, precision, recovery rate of different concentration was used to evaluate the pros and cons of the method. Then the optimization method was used to detect content of PAEs in Jiaozhou bay. It is very significant to provide technical support and data support for the marine pollution monitoring and control.The results of establish SBSE-GC-MS showed that:the more volume the stir bar coated with PDMS, the better extraction efficiency would get. The best extraction time was 2h. The best extraction temperature was 25 ℃. The best addition amount of NaCl was 5%, the best addition amount of methanol 10%. The best desorption time was 50 min. The best ratio of desorption solvent between methanol and acetonitrile was 4 to 1. The linear relationship between the ratio peak area of the PAEs to internal standard and the concentration of PAEs was significant correlated. The correlation coefficients were more than 0.99. The linear range of the SBSE-GC-MS was from 0.01 μg/L to 500ug/L. The detection limit and the quantitative limit were low enough to detect trace PAEs in water sample. The recovery rates of the PAEs were close to the theory recovery.The results of detecting PAEs with GC-MS showed that:the chromatographic peak of all the PAEs could appear under the specified condition of GC-MS, they were complete separation. The detection limit range of the equipment was from 0.07 to 5.71 μg/L. The quantification limit range of the equipment was from 0.023 to 193μg/L. The linear relationship of the PAEs chromatographic peak area and concentrations were good, and the correlation coefficients were greater than 0.92. The GC-MS equipment could direct used to determine PAEs. The direct detection range of the equipment was large enough. And the direct detection range of the equipment would decrease with the increase of carbon chain of PAEs.The results of detect PAEs in Jiaozhou bay by SBSE-GC-MS showed that:PAEs were detect in all the sample and the major river estuary, and the detection rate of DMP and DEP were 100%. The types of PAEs in sample site near Jiaozhou bay ship route and Jiaozhou bay bridge were more than the other sites. The concentration of BBzP, DEHP and DOP were much higher than the other PAEs. The sum concentration of the 15 PAEs in southeast jiaozhou bay, the estuary of Li Cunhe and the sea mooring river were much higher than the rest. The lower concentration was mainly in the central of Jiaozhou bay and Jiaozhou bay mouth into the yellow sea region.