Reserch On Detection Methods Of Perfluorinated Compounds Precursors And Isomers

Perfluorinated compounds（PFCs）,as a type of persistent organic pollutants（POPs）,are widely found in various environmental matrices and biological matrices.Studies have shown that PFCs has strong hepatotoxicity,embryotoxicity,carcinogenicity and teratogenicity,which may lead to endocrine disorders and reproductive dysfunction,and can carry out maternal metastasis through placental and umbilical cord blood,which aggravates the potential health risks for humans.PFCs precursors and isomers have specificity of ecological and human health risks,.The potential ecological and health risks of PFCs can be accurately assessed only if the precursors of PFCs and their isomers are taken into account.The relative research on PFCs precursor compounds and isomers are few at home and abroad,so there is an urgent need to establish sensitive and reliable quantitative techniques for sample pretreatment and detection.In this paper,taking PFCs precursors and isomers of as the main research goal,a gas chromatography-mass spectrometry method（GC-MS）for the determination of PFCs was established.The main research content is as follows:（1）Acetyl chloride methanol was successfully used to derive the dimethyl branched chain isomer of perfluorooctanoic acid（5,5m₂-PFOA）.GC-MS was used for detection,and the derivative product 5,5m₂-PFOA was able to be baseline separated and successfully separated from linear PFOA.This provides diversified technical means for the isomer separation and qualitative detection of PFCs.The method is applicable to both aqueous and acetonitrile media,and was applied to the derivation of 7 linear perfluoroalkyl carboxylic acids（C6-C12）and 2 branched isomer（iso-PFNA）.According to the ion characteristics of the fragments in the derivative mass spectrum,a gas chromatography-quadrupole mass spectrometer was established to select the ion monitoring mode for detection.The instrument detection limits for the 7 target components range from 0.05-0.15 ng/m L,and the quantification limits range from 0.15-0.45 ng/m L.The obtained method has a low detection limit and can meet the needs of trace detection.（2）The derivatization reagent uses IBCF,pyridine as catalyst,corresponding alkyl alcohol as promoter,and combined with GC-EI-MS to detect PFCAs in surface seawater.Glass fiber filter membrane is used for filtration and pretreatment,combined with HLB solid-phase extraction to enrich and purify PFCAs in seawater matrix.After derivatization,qualitative and quantitative analysis was performed using GC-EI-MS,and iso-PFNA was selected as the internal standard for quantification using the internal standard method.The IDL range between 0.15-0.35 ng/m L,IQL range is 0.45-1.045 ng/m L.The detection limit of the method is 0.06-0.34 ng/L,the recovery rate of blank matrix sample spiking ranges from 61.54%-103.60%,and the RSD range is from 3%-14.5%.The method was applied to10 surface seawater samples collected from three coastal cities in China,and three different concentrations of PFCAs were detected in these samples,with concentrations ranging from 5.7-14.2 ng/L.（3）The pre-treatment method for fluorotelomer alcohols（FTOHs）was established and improved in high water content biological matrices,and tested 5 agricultural products.After freezing intervention,methanol extraction and graphite carbon black purification,agricultural products can be directly entered into GC-MS detection without concentration and enrichment.The method used external standard method for quantification,with a detection limit of 0.6-1.77 ng/g dry weight for 6:2 FTOH and 0.72-1.95 ng/g dry weight for 8:2 FTOH.The recovery rates of the two FTOH were basically between 80%-110%,and the standard deviation was less than 20%.The method has a low detection limit,good accuracy,high precision and high sensitivity,meeting the needs of trace detection.