Reserch On Detection Methods Of Perfluoroalkyl Carboxylic Acids

Perfluoroalkyl carboxylic acids?PFCAs?are a class of persistent organic pollutants.The characteristics including chemical stability,heat-resistance,and water and oil repellency that make PFCAs widely used for a range of industrial and commercial applications.PFCAs are widely detected in the global environment and pose negative effects on human health in recent years.The environmental persistence,hardly-degradable characteristic,bioaccumulation and toxic effects of the PFCAs have caused great concerns.The development of detection methods for complex matrices and the environmental assessment of PFCAs are the focus of environmental analytical chemistry.The new derivatization agents,2,3,4,5,6-pentafluorobenzyl bromide and amide acetals,were employed to determine PFCAs simultaneously with gas chromatography technique in this study.The main contents are as follows:?1?2,3,4,5,6-Pentafluorobenzyl bromide?PFBBr?was employed to determine seven PFCAs simultaneously in tap water with gas chromatography-mass spectrometry.The water samples were purified and enriched by solid-phase extraction,PFCAs derivatization with PFBBr under catalysis by K₂CO₃,reaction time of 55?for 60 min,perfluoro-3,5,5-trimethylhexanoic acid were utilized as the internal standard and PFCAs derivatives were quantified by internal standard method.The solid-phase extraction conditions were optimized and the effects of the derivatization conditions on the derivatization efficiency were studied.The fragmentation pathways of PFCAs pentafluorobenzyl esters were analyzed by mass spectrometry,and the instrument conditions were optimized.The results showed that the method detection limits?MDLs?ranged from 0.1-0.28 ng/L,the recoveries ranged from 41.6%-101.8%with relative standard deviations?RSDs?of 3.0%-14.5%.The14 tap water samples collected from different places of China were analyzed by this method.?2?The derivatization method using a series of amide acetals as derivatization reagents,along with gas chromatography-mass spectrometry and gas chromatography tandem mass spectrometry analysis were developed and validated for simultaneous determination of 9PFCAs.The structures and fragmentation pathways of PFCAs derivatives were deduced and verified.The newly-found derivatives improved the sensitivity of the detection of PFCAs by GC.The mechanism and conditions of the derivatization reaction were discussed and optimized,two economical and reliable internal standards were selected to quantify PFCAs derivatives.The results showed that the instrument detection limits?IDLs?were lower than0.02 pg/?L,RSDs ranged from 1.04%-5.48%.?3?A method for the determination of PFCAs in biological matrix using derivatization method and gas chromatography tandem mass spectrometry was established.The alkaline digestion followed by solid-phase extraction cleanup method was used for the pretreatment,N,N-dimethylformamide dimethyl acetal was used as the derivatization reagent,the PFCAs derivatives detected by gas chromatography-tandem mass spectrometry,the internal standard method was used for quantitative analysis.The MDLs ranged from 0.04-0.10 ng/g,recoveries ranged between 54.72%to 107.29%.The RSDs were in the range of 1.53%to11.89%.The derivatization method for gas chromatography is suitable for the simultaneous detection of PFCAs in complex matrix.The method is easy-implementation with high sensitivity.The results of the samples show shellfish are contaminated by long-chain PFCAs.Attention should be paid to the pollution of the PFCAs in the clam samples.