Preparation Of Polypyrrole-based Composite Nanomaterials And Their Application In The In-tube Solid Phase Microextraction

In tube solid-phase microextraction(IT-SPME)is a novel sample pretreatment technique.It has been widely applied in various fields due to its time-efficient,simplicity and less solvent consumption.Moreover,IT-SPME allows for the convenient automation of the extraction process by on-line coupling to HPLC and LC/MS.The online IT-SPME-HPLC and IT-SPME-LC/MS permits the integration of extraction,concentration,desorption and injection,not only significant reducing analysis time and the sources of error,but increasing precision and sensitivity relative to manual off-line preparation process.The past decade has witnessed the rapid development of online IT-SPME coupling to analytical instruments.But commercial coating suffers from the shortcomings of poor solvent stability,short lifetime and high analysis cost.Therefore,the development of new IT-SPME coatings with high solvent and mechanical stability,long lifetime and easy preparation process has become the focus of research workers.In this paper,two kinds of new composite materials were synthesized by a simple electrodeposition method and used for on-line IT-SPME.The developed IT-SPME method was coupled with HPLC and LC/MS for the analysis of trace metabolites in biological samples.The concrete research content is as follows:1.The preparation of polypyrrole/graphene(PPy/G)composite coating was carried out by a facile electrochemical polymerization strategy on the inner surface of a stainless steel tube.Based on the coating tube,a novel online in-tube solid-phase microextraction-high performance liquid chromatography(IT-SPME-HPLC)was developed and applied for the extraction of aldehydes in the human exhaled breath condensates(EBC).Online IT-SPME-HPLC method has many advantages such as time and cost saving,simple operation,high sensitivity and precision.The hybrid PPy/G nanocomposite exhibits remarkable chemical and mechanical stability,high selectivity,and satisfactory extraction performance toward aldehyde compounds.Some parameters related to extraction efficiency were optimized systematically.Under the optimal conditions,the recoveries of the aldehyde compounds at three spiked concentration levels varied in the range of 85%-117%.Good linearity was obtained with excellent correlation coefficients(R2)being larger than 0.994.The relative standard deviations(n=5)of the method ranged from 1.7%to 11.3%and the limits of detection were between 2.3 and 3.7 nmol L-1.The successful application of the proposed method in human EBC indicated that it is a promising approach for the determination of trace aldehyde metabolites in complex EBC samples.2.The polypyrrole/zinc oxide(PPy/ZnO)coating was prepared by a facile electrochemical polymerization strategy on the inner surface of a stainless steel tube.Based on the coating tube,a novel online in-tube solid-phase microextraction-liquid chromatography/mass spectrometry(IT-SPME-LC/MS)method was developed and applied for the extraction of monohydroxy polycyclic aromatic hydrocarbons(OH-PAHs)in human urine.Some features of coating including morphology,solvent stability,lifetime were investigated in detail.The experimental conditions affecting the extraction were optimized systematically.Under the optimal conditions,the detection limits were in the range of 0.039-0.050 ng mL-1,and good linearity was obtained with excellent correlation coefficients(R2)being larger than 0.9967.The repeatability(n=5),expressed as relative standard deviation,ranged between 2.5%and 9.4%.The method offers the advantage of process simplicity,rapid,and cost saving in the analysis of human urinary OH-PAHs in two different cities of Hubei province.Results show that the OH-PAHs concentration in human metabolites is closely related with surroundings.The method provides a potential tool in the biological monitoring of human exposure to PAHs.