Study On Analytical Methods Of Pahs And PCBs In Marine Sediments And Preparation Of PCBs Standards

In recent years,as the country vigorously develops the marine industry,accelerates the process of urbanization development,and develops coastal industrialization,the quality of the marine environment is deteriorating.The results of monitoring the quality of sediments in coastal waters indicate that the main pollutants in marine sediments are inorganic mercury,copper,arsenic,cadmium,lead and organic polycyclic aromatic hydrocarbons and polychlorinated biphenyls.In recent years,the analysis and research on organic pollutants in marine sediments has become a research hotspot at home and abroad,which is of great significance for environmental monitoring and protection.In this paper,31 kinds of polycyclic aromatic hydrocarbons(PAHs)and 7 polychlorinated biphenyls(PCBs)were analyzed by using marine sediments as research system.A new pretreatment method for accelerated solvent extraction and purification was established to achieve integrated extraction and purification.The aim is to achieve fast and reliable detection of PAHs and PCBs by using gas chromatography triple quadrupole mass spectrometry and gas chromatography electron impact ionization source mass spectrometry.In this paper,an integrated pretreatment method for accelerating solvent extraction and purification was adopted,and the sources of PAHs interferants in the experimental process were analyzed and quality control was carried out.The factors affecting the extraction and purification efficiency were systematically studied,including the solvent ratio of PLE,extraction temperature,extraction times and static time.The types of PLE adsorbent fillers,the amount of PLE adsorbent fillers and the way of PLE adsorbent fillers were also investigated.At the same time,the source analysis,quantification and quality control of the interferences were carried out in each step of the experiment.The results showed that using 0.5 g silica gel as purification filler,extracting solvent:n-hexane:dichloromethane(1:1,v/v),extraction temperature:120?,cycle times:4 times,static extraction:10 minutes can achieve satisfactory extraction and purification effect.At the same time,the influence of PAHs in the air on the experimental results was reduced by the quality control of PAHs interferants in the pretreatment and detection process.Under the above conditions,the recoveries of 31 PAHs and 7 PCBs were 81.47-100.79%and 96.51-110.00%,respectively,and RSD were 2.5%and below.The established method has a good linear relationship,and the correlation coefficients of 31 PAHs(linear range:2-250 ng·g-1)and 7 PCBs(linear range:2-250 ng·g-1)are 0.9964-0.9998 and 0.9982-0.9998.The minimum detection limits(LODs)of the established analytical methods for PAHs and PCBs were 0.21-1 5.23 ng·g-1 and 0.54-1.14 ng·g-1,respectively,and the lowest limit of quantification(LOQs)was 0.71-50.75 ng·g-1 and 1.80-3.79 ng·g-1.The established method was applied to the detection and analysis of marine sediment samples collected from different regions.The results show that the established method has the advantages of high efficiency,simplicity and high sensitivity,and can be applied to the detection of PAHs and PCBs in marine sediment samples.In addition,this paper studied the purity and purity of the standard solution,the uniformity,stability and uncertainty of the standard solution with the preparation and calibration values of 7 kinds of PCBs single standard solution and mixed standard solution.These are all important for the preparation of reference materials.The standard solution was fixed by gas chromatography triple quadrupole mass spectrometry and gas chromatography electron impact ionization source mass spectrometry.When investigating the uniformity of the standard solution,the F-test is used,that is,the F value measured by the uniformity is less than the matching F-threshold value,which proves that the distribution of PCBs in the single PCB solution and the mixed standard solution is uniform.The stability of the prepared standard solution was investigated by T test.The calculated T values were all less than the corresponding T-threshold values,indicating that the prepared 7 kinds of PCBs single standard solution and mixed standard solution were stable in 15 months.Finally,the prepared 7 kinds of PCBs single standard solution and mixed standard solution were evaluated for uncertainty,and the set value and uncertainty of the standard solution were obtained.