Development For Standard Reference Materials Of Polycyclic Aromatic Hydrocarbons In Marine Sediments

Environmental standard reference materials were used for environmental monitoring,which were mainly prepared by environmental matrices as candidates.Target pollutants in candidates would be certified.Standard reference materials of marine sediments were the most important part of environmental standard reference materials.The development procedures of matrix reference materials from marine sediments,e.g.,candidates,the analytical and certificating methods,inspection in preparation,etc.This work was supported by “Development of Standard Reference Material for Marine Environmental Monitoring”(2016YFF0201104).This task was the subproject of “the Research on Urgently needed Chemical Component Quantity Standard Reference Materials in the Key Area”,“National Key R&D Program of China”.The paper has made an in-depth discussion of the developing process of marine sediment standard reference materials of polycyclic aromatic hydrocarbons(PAHs).Sixteen PAHs in seven kinds of marine sediment candidates from Bohai sea and Dalian Bay were analyzed.The pretreatment methods of PAHs in sediments were optimized by comparing the extraction efficiencies of PAHs in marine sediments standard reference materials under different conditions.The developing process of marine sediment standard reference materials of PAHs was further explored.The main research results were as follows:(1)Seven sediment samples as marine sediment standard reference material candidates were collected from different sea areas,and sixteen PAHs were investigated.The total PAH concentrations ranged from 141.71 ng/g to 3322.72 ng/g.The sediment samples have certain representativeness,because PAH levels in sediment samples have reflected the current situation of PAHs in coastal zone of China.(2)The effects of different pretreatment conditions on the recovery of PAHs in sediments were compared.The recovery by the optimized method was 66.4% to 106%.A series of standard concentration gradient solutions were set up.The correlation between concentration ratio and peak area ratio was established.The linear relationship of the standard curve was good(R>0.995).The detection limit was determined with the lowest concentration.The detection limit by the lowest concentration point in the standard curve was determinated.The results showed high sensitivity that the limits of detection of sixteen PAHs were 0.004 ng/g.~0.107 ng/g.(3)Under the optimized pretreatment method,the homogeneities of seven kinds of marine sediments was preliminarily tested.After test,the F statistic of the three candidate samples were less than 3.020.It means these samples were no significant difference between different part of the samples.Those samples were passed homogeneity test.(4)Different preservation conditions of standard reference materials were contrasted.It was illustrated that some components discriminant function(f(a))of the candidate samples at that temperature were larger than zero and the slopes were less than zero.The components were changed significantly with time and influenced by temperature with decreasing trends at 60?.The PAHs were no significant change at-20 ?.The discriminant function(f(a))of the candidate samples at that temperature were less than zero.The samples were preserved at-20 for ? twenty-two weeks to test the stability.It showed that there was no significant change in all components of the standard reference materials within twenty-two weeks.The stability test was passed.(5)After the measurement uncertainty synthesis,the relative uncertainty of fourteen PAHs samples in Jinzhou Bay and Dalian Bay ranged from 17% to 32.8% and 10.3% to 24.5%,respectively.The relative uncertainty of ten PAHs in Liaodong Bay ranged from 21.4% to 43.0%.The relative uncertainty of eleven PAHs species below five rings in BH-64 sample of the central Bohai Sea was 10.4% to 44.1%.The concentration ranges of mean values and uncertainties was wide,and the measuring range was different.These samples should be developed into a variety of marine sediment standard reference materials of PAHs.It would also be used to monitor different concentrations of PAHs in marine sediment measurements.Although the homogeneities of PAHs in other sediments were poor,Values of some PAH analytes suited as reference values in standard reference materials.