| Urine contains many human metabolites that are complex and susceptible to disease.Therefore,urine determination does have certain indications for disease diagnosis.Lung cancer is one of the most serious malignancies in the world with high morbidity and mortality,which is a severe threat to human health.Early diagnosis of lung cancer is particularly important for improving patient survival rate.Studies have shown that the level of 8-hydroxy-2'-deoxyguanosine(8-OHdG)as a major product of DNA oxidative damage in cancer cells was significantly higher than that of normal tissue cells.Thus,the urinary metabolite 8-OHdG is regarded as a potential biomarker of lung cancer,and the combining with chromatographic techniques can provide a safe and non-invasive method for early diagnosis and treatment of cancer.On the other hand,residual pollutants caused by the abuse of pesticides also pose a threat to human health through the food chain for bio-concentration.Mung bean sprouts,a legume plant with high nutritional value,are very popular in daily life.However,the "poisonous sprouts" incident that occurred in the past aroused widespread concern,and the current research on the detection of pesticide residues in bean sprouts is very limited.How to monitor pesticide residues in bean sprouts effectively is an urgent problem to be solved.In addition,both 8-OHdG in urine and pesticide residues in bean sprouts face the challenges such as complex sample matrix and low target concentration.Therefore,it is crucial to choose appropriate sample preparation method to achieve high sample enrichment and effective purification.On line micro solid phase extraction(on-line-?-SPE)and solid-phase microextraction(SPME)are new pre-concentration methods that have received extensive attention.The ?-SPE extraction device is combined with on-line technology to realize the integrated analysis of sample extraction and mobile phase desorption through valve switching with a high degree of automation.SPME integrates sampling,enrichment,analysis,and sample injection,and does not require large amounts of organic solvents.Both of them shorten the analysis time greatly,improve the sensitivity and accuracy of the method,and are environmentally friendly.In the sample preparation process,the selection of the stationary phase material also restricts the enrichment effect of the target.The development of highly efficient and sensitive adsorption materials has always been a research hotspot in the field of complex matrix sample detection.In recent years,electrospun nanomaterials with large specific surface area and high porosity have been widely adopted in the area of SPE and SPME.Moreover,the mechanical properties and thermal stability of the electrospun material are significantly improved after heat treatment,further extending the application range.Therefore,two kinds of nanocomposites were prepared by electrospinning technology and used as ?-SPE and SPME adsorbents for online combination with liquid chromatography-mass spectrometry(LC-MS)and gas chromatography-mass spectrometry(GC-MS),respectively.The 8-OHdG in human urine and the fungicide residues in bean sprouts were examined.The contents of this paper are summarized as follows:1.A polystyrene/graphene(PS/G)nanomaterial was prepared by electrospinning and used as on-line ?-SPE adsorbent.The new online method was established by coupling?-SPE coupling with LC-MS for the determination of urinary 8-OHdG.We investigated the morphology,anti-matrix interference ability,extraction efficiency of nanofiber materials,and optimized experimental factors that affect the enrichment of 8-OHdG.The three-dimensional network structure of PS/G endowed it a very high specific surface area,good extraction efficiency,and certain resistance ability to matrix interference.Compared with offline mode,the online analysis method had a high degree of automation,which could achieve rapid measurement of the target with high-throughput,improved accuracy and sensitivity.The proposed method had exhibited a good linear relationship between 0.1-100 ?g L-1 with the limit of detection to be 0.06 ?g L-1.The intra-day and inter-day relative standard deviations were below 4.1%and 10.1%,respectively.And the recovery rate varied in the range of 63%-75%.The results have shown that the method has high sensitivity and good reproducibility and can be applied to detect 8-OHdG in the urine of lung cancer patients.2.Polystyrene/graphene@silica(PS/G@SiO2)nanocomposites were fabricated by electrospinning and the mechanical strength and thermal stability of the as-spun material were improved by heat treatment.The SPME extraction coating was directly inserted into the GC-MS injector to perform thermal desorption.The rough surface of calcined composite material possessed a large specific surface area,high extraction efficiency,and could be repeatedly used.We selected two new types of fungicides(Y13149,Y12196)as targets and optimized various parameters that might affect the extraction efficiency.Studies had been carried out to investigate residual accumulation and concentration distribution of fungicides in plants.Under the optimal conditions,the detection limits,precision,reproducibility,and recovery of the method were evaluated.Satisfactory mean recoveries of 99%and 72%were obtained for Y13149 and Y12196 with the relative standard deviations(RSD)under 16.3%.The result also exhibited low detection limit(0.08 ?g·L-1 for Y13149,0.06 ?g·L-1 for Y12196)and good liner range(0.3-100 ?g·L-1)with the correlation coefficients(R2)excessed 0.99.The results above have exhibited a reliable method with high accuracy and sensitivity.In addition,the mung bean sprouts cultivated in the laboratory under certain conditions were used as the plant models.The optimized SPME-GC-MS method was employed for fungicides analysis in mung bean sprouts through in vitro and in vivo mode.Furthermore,in vivo extractions were executed to trace the accumulation of fungicides in mung bean sprouts. |
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