Muti-fiber Solid Phase Microextraction And Its Application In Gas Chromatography

Fiber solid phase microextraction(fiber SPME),a simple,green and efficient chromatographic pretreatment technology,which integrates sampling,extraction and enrichment,has been well applied and developed in recent years.Fibers are the core of the SPME technology.Currently,there are limited commercial fibers,which cannot meet all practical needs.Therefore,it is necessary to study new solid-phase microextraction fibers to meet the needs of different analytical purposes.In view of the problems of commercial fibers,such as high cost,frequent replacement and insufficient extraction of some kinds of coatings,a novel multi-fiber SPME assembly composed of three straight stainless steel filaments,a silicone cap and a stainless steel capillary,was developed and applied to extract and enrich target analytes in environmental water samples.The cyclic voltammetry method was used to electrodeposit o-aminobenzene sulfonic acid self-doped polyaniline and multiwalled carbon nanotubes(SPAN/MWCNT(s))blended composite on the fiber substrates.The influence of electrochemical parameters and solution conditions on coating preparation was investigated,and scanning electron microscope,infrared spectrometry and other characterization methods were used to characterize the composite coating.N,N-Diethylaniline(NNDEA)was designated as the standard analyte.A gas chromatograph-flame ionization detector was used in combination with headspace solid phase microextraction to investigate the effects of extraction time,extraction temperature,salt concentration,and solution p H on extraction efficiency.And the performance of the SPME fibers,such as stability,enrichment rate,linearity,and precision,was evaluated.Using the SPME fibers,adsorption-desorption process of NNDEA standard solution at 280℃ was repeated for 13 times in 500 min,and no notable loss of the extraction efficiency was found,demonstrating that the coating has a good thermal stability.Also,the thermogravimetric analysis curve proved that the coating has good stability below 363℃.The relative standard deviations(RSDs)obtained using an identical multi-fiber SPME assembly in an identical day and different days are 3.2%(n=5)and 8.2%(n=3),respectively.The RSD obtained using different multi-fiber SPME assemblies prepared in different batches is 8.5%(n=3).Using SPAN/MWCNTs fiber coating for headspace sampling,NNDEA shows a good linear relationship in the range of 0.96 to 965 ng/m L,and the detection limit is 0.18 ng/m L,the standard curve is y=12.341+628.16,and the correlation coefficient is 0.9995.The enrichment rate is 186959,indicating that the multi-fiber coating has a good enrichment effect.Similarly,the extraction conditions of o-dichlorobenzene(o-DCB)and o-chlorophenol(o-CP)were optimized using the multi-fiber SPME component,and then gas chromatography analysis of NNDEA,o-DCB and o-CP in water samples was carried out.In the ranges of0.13-131 ng/m L and 13.36-1336 ng/m L,the standard curves of o-DCB and o-CP are y=16358x+2311.6,y=1.7851x+754.91,the correlation coefficients are 0.9994 and 0.9983,and the detection limits(S/N=3)are 36.11 ng/L and 3.91 ng/m L.Moreover,the spiked recovery analysis of NNDEA,o-DCB and o-CP in water samples was performed at three different addition concentration levels,and the recovery rates are measured to 81.2%-102.0%,71.0%-129.0% and 98.8%-110%,respectively.