| Air pollution threatens not only people's physiology health but also their mental health.Ascertaining the main components of air pollutants and their harm to human body can help people to monitor air pollution more purposefully and to prevent,diagnose and treat diseases more effectively.The frequent occurrence of fog and haze makes particulate matter become the focus of people's attention.One of the main components of air particulate matter is organic pollutants,and polycyclic aromatic hydrocarbons(PAHs)are a class of these organic compounds,which have been research hotspots because of the carcinogenic,teratogenic and mutagenic properties.PAHs can enter the human body directly with fine particles through the respiratory tract,causing a variety of health problems,such as respiratory-related diseases and allergic diseases,and even neurological impairment.As a stress source,pollutants can activate the hypothalamus-pituitary-adrenal system(HPA axis)and then lead to a series of physiological changes.Cortisol is the representative physiological index of HPA axis.Studying the correlation between PAHs and the stress marker--cortisol is helpful to clarify the components of air pollutants which do harm to health,and to provide a basis for the selection of biomarkers for assessment of population exposure to particulate matter.Due to the trace or ultra-trace distribution of PAHs in the ambient air,the key to accurate and sensitive determination of PAHs is to establish an efficient sample collection and sample pre-processing method.At present,the collection of particle-phase PAHs often relies on expensive large-flow sampling equipment,suggesting that the sampling efficiency of existing sampling membranes needs to be improved.Soxhlet extraction and ultrasonic extraction are commonly used for sample preparation.Soxhlet extraction consumes lots of time and organic solvents,and the following procedure--rotating evaporation can result in the loss of volatile or semi-volatile PAHs.The loss of PAHs can also occur during nitrogen blowing and resolving process following the ultrasonic extraction.For the analysis of cortisol,blood is commonly used as human samples,but its invasive sampling process can cause the increase of cortisol,affecting the accuracy of detection.Saliva and urine are both non-invasive samples.The level of cortisol in saliva is lower than that in urine,which makes it harder to determine salivary cortisol.Usually,immunoassay or liquid chromatography-mass spectrometry(LC-MS)is used for salivary cortisol determination.However,immunoassay has the technical defects of cross-reaction interference and higher determination results than actual ones,as well as LC-MS is expensive indeed.Because of the background disturbance of biological samples and the low concentration of biochemical substances,the cortisol in urine samples usually needs to be extracted and concentrated before being determinated by high performance liquid chromatography-ultraviolet detection(HPLC-UV).Nanofibers play an important role in varies fields such as adsorption and filtration of substances because of their large specific surface area and high porosity.Electrospinning technology is a simple method for nanofibers preparation.In this dissertation,electrospun nanofibers were used as filters or adsorbents to prepare practical sampling devices for the collection of particle-phase PAHs and sample pre-processing devices for the determination of PAHs and cortisol.Gas chromatography-mass spectrometry(GC-MS)was developed for the determination of particle-phase PAHs and HPLC-UV was used for the determination of urinary glucocorticoid.These two methods were preliminarily applied to a study in preschool children.The main work of this dissertation is as follows:(1)Study on the enrichment of PAHs in environmental samplesAt present,there are still some shortcomings in the concentration of sampled PAHs during the pretreatment procedure of air samples.A packed-fibers solid phase extraction(PFSPE)method used for simultaneous concentration of 16 priority PAHs was preliminarily established,by selecting suitable extraction materials and optimizing the extraction conditions.The results indicated that every PAHs had a good absolute recovery.(2)Establishment of detection method for particle-phase PAHsIn view of the drawbacks of current sampling and pretreatment method for particle-phase PAHs,electrospun nanofibrous membranes were prepared and its particle trapping capacity was compared with that of commercial quartz-fiber membranes.The results showed that nanofibrous membranes had better particle trapping capacity.Then an appropriate solvent was chosen and shaking extraction was used for extracting sampled PAHs on the membrane.Combined with PFSPE and GC-MS,the analytical method of particle-phase PAHs was established.The experimental results showed that the method performed good with wide linearity(correlation coefficient:0.9929~0.9995;linear range:0.17~69.4 ng/m~3),lowest detection limit(0.09 ng/m~3~1.69 ng/m~3),and good accuracy(recovery:79.2%~109.1%)and precision(intraday and interday precision:4.3%~10.6%and 4.8%~11.6%).(3)Establishment of analytical method for urinary glucocorticoid and its applicationIn consideration of the low concentration of analytes and the large matrix interference in biological samples,a method for the determination of urinary glucocorticoid was established based on PFSPE coupled with HPLC-UV.The experimental results showed that the method performed good with wide linearity(correlation coefficient:cortisone:0.9968 and cortisol:0.9989;linear range:10~1000 ng/ml),lowest detection limit(cortisone:4 ng/ml;cortisol:5ng/ml),and good accuracy(recovery:86.3%~111.4%)and precision(intraday and interday precision:2.8%~7.3%and 4.3%~10.2%).Then the method was used to analyse urinary cortisol and cortisone levels of college students before and after a running test.The results indicated that cortisol was significantly higher in the post running versus pre running condition in students,suggesting that the method was suitable for cohort study.(4)Study on the correlation between particle-phase PAHs level and urinary glucocorticoid level in childrenIn this study,children were recruited from two different kindergartens.Particle-phase PAHs detection method extablished previously was used to collect and analyse particle-phase PAHs in the ambient air of kindergartens.And urinary glucocorticoid detection method established previously was used to determinate cortisone and cortisol in children's urines.The results suggested that the increase of urinary cortisol level in children might be affected by the rise of particle-phase PAHs level in air. |
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