Study On Detecting Method Of Perfluorooctanoic Acid In Textile And Textile Finishing Agent

A method of detecting small quantity and harmful perfluorooctanoic acid in textile and textile finishing agent was established,and in which an internal standard method was adopted.There were three sections in this paper:pretreatment—extraction of PFOA from samples;derivation of PFOA; detection by GC-MS.During the pretreatment,some extracting effects of several methods were studied,like the methods of Soxhlet,boiling,ultrasonic,ultrasonic-microwave synergistic extraction,and in the end the ultrasonic-microwave synergistic extraction was chosen as the best way of extracting method according to the extracting effect on real sample.The optimal condition was determined according to an orthogonal design which mainly studied on different influence factors（such as microwave power,time of extraction,tempreture of extraction,solvent of extraction）.It was summing-up as: microwave power 200W,time of extraction 50min,tempreture of extraction 70℃,volume ratio of the solvent H₂O:CH₃OH=1:1.During the derivation,the way of esterifying the target substance PFOA and the internal standard substance PFDA was determined,and the influence factors（such as the reacting time,the tempreture of the water bath,and the ratio of the CH₃OH and CH₃COCl） were discussed.As a new method,the ultrasonic oscillations was inducted to the process of esterfying.According to the results,it could be found that the reacting time could be reduced greatly in the presence of the ultrasonic oscillations.The optimal condition was determined according to monofactorial experiment:PFOA and PFDA could be esterified in the same reaction system at the same time, tempreture of the water bath was 55℃,the esterifying time with ultrasonic oscillations was 45min, volume ratio of CH₃OH:CH₃COCl was 2:1.During the detection,GC-MS was used to detect the target substance and internal standard substance after they were esterified.First,in order to regulate instrument parameters,the heating-up program,the flow rate of carrier gas,and the quantity of injecting sample were set.Then,the derivatives of standard solution PFOA and internal standard substance PFDA were detected by GC-MS.Adopted the mode of full scan and catched the information of compound structure,the retention time of methyl ester of PFOA and PFDA was confirmed.Again the mode of SIM was chosen in order to determine the ion fragment（m/z=59） to quantitative analysis.Second,a series of PFOA standard solutions on different concentration were prepared,and the corresponding same concentration of PFDA was added to above solution respectively.After esterified,they were detected under the setting condition.The standard curve was made according to the ratio of peak area（ester of PFOA:ester of PFDA）-the concentration of PFOA.It was found that the linear relation was excellent in 0～50μg/mL.The percent recovery,detecting limit,precision and repeatability were also studied under the detecting conditions.The percent recovery of samples was steadly 80～100%,the detecting limit was 0.0126μg/mL,repeatability and precision were also satisfied with RSD＜1%and RSD＜10% respectively according to the retention time and peak area on the detection of PFOA during 5 continuous days.