| Lung cancer is a leading cause of cancer death and the mortality rate of lung cancer is still rising, now it has become one of the hot spots in the field of clinical research. However, due to the lack of early diagnose and timely effective surgical treatment, their5-year survival rate could not be reach to15%. Moreover, conventional diagnostic methods, such as biopsy, fluorescence bronchoscopy and spiral CT scanning, are often expensive and the cycle is a little long. Besides, cancer patients may suffer from great pain during the conventional diagnosis.Recently, exhaled breath testing is becoming an increasingly important non-invasive and new diagnostic method, a disease can be assessed through detecting the composition of the exhaled breath gas of the patients which reflects the etabolism of the corresponding tissue cell and heath status and disease types. These compounds in EBC including alkanes and aldehydes are the typical biomakers, to some extent, the concentrations of these compounds is associated with the extent of oxidative damage. Therefore, the determination of metabolites of these small molecular makers is expected to provide theoretical auxiliary basis for early diagnosis of cancer. But owing to the concentration of these compounds is very low and the matrix is relatively complex, it is difficult to direct determination of these compounds. Thereby, it is vital to adopt an appropriate sample preparation method to improve the accuracy and sensitivity of the methods before analysis.In recent years, as a kind of solvent-free or less solvents, easy operation of pre-treatment methods, solid phase microextraction technology has attaracted an increasing interest and developed rapidly, it is used in variety fields, including food, environment, biology, forensic field, etc. The methods is classified as PDMS and PDMS/DVB fiber extraction, molecularly imprinted monolithic column extraction, and capillary monolithic column extraction, etc. In addition, great attention has been paid to the functionalization of magnetic nanomaterials (MNPs) due to the outstanding potential advantages such as large surface areas, high extraction efficiency and easy to separation. The modification of MNPs with restricted access group is a new trend.In our work, three kinds of sample preparation methods have been developed including polydimethylsiloxane sieve based-Sorption extraction, methacrylic acid diviylbenzene monolithic frit based-solid phase microextraction and magnetic solid-phase microextraction. These methods were coupled to HPLC/UV and used for the analysis of aldehyde compounds in human EBC. The main contents are listed as follows:1. A porous polypropylene frit was used as a novel support to load PDMS and the synthesized PDMS-frit was chosen as extraction medium for adsorption of target compounds. In the experiments, a series of parameters affecting the derivatization-extraction efficiency were optimized, and the proposed method was compared with the conventional stir bar sorptive extraction (SBSE). The method has been successfully used to determine aldehydes in breath gas condensate of healthy people and lung cancer patients by combination with HPLC. Satisfied results were obtained, of which RSD ranged from3.0%to16.6%and recoveries ranged from80%to114%. The developed method is a simple, fast analysis speed, high extraction efficiency.2. A monolithic copolymer of methacrylic acid and divinylbenzene [poly (MAA-co-DVB)] was synthesized and used as a new extraction phase of the solid-phase microextraction (SPME). The SPME method combined with high-performance liquid chromatography was ultilized for the determination of aldehydes in EBC samples. In this methods, the experimental parameters were investigated, including polymerization, derivatization and extraction. Detection limits of1.1-17.5nmol L-1were obtained for the aldehydes, with a linear response in the concentration range of0.005-10μmol L-1and recoveries ranged from76%to142%for the spiked EBC samples. It indicates that this method is reliable and effective in conventional detection methods.3. A MSPE-HPLC/UV method using Tween-20-MNPs as extraction phase of magnetic solid-phase microextraction (MSPME) for the determination of six aldehydes in different EBC samples has been developed. The parameters affecting the extraction such as concentration of DNPH, the amount of magnetic nanoparticles, the type and volume of desorption solvent were investigated in detail and was used for determination of derivatizative of small molecul metabolites (aldehydes) in health and patients samples. Detection limits (S/N=3) of3.3nmol L-1-22.7nmol L-1were obtained for the aldehydes and the related coefficients (R) were0.9957-0.9996. The developed method is a simple, fast analysis speed, high extraction efficiency, good biocompatibility, suitable for the conventional analysis of biological samples. |
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