Preparation Of Novel Solid Phase Microextraction Fiber Coatings And Their Application In The Analysis Of Volatile Metabolites In Exhaled Breath Vapor

Lung cancer has been the leading cause of death because of late detection and ineffective treatment. If an early diagnosis of lung cancer can be achieved, it would improve prognosis and enlarge therapy options, thus people of getting lung cancer can improve survival. Recently, breath test has been considered as one of the potential diagnostic methods because of its safety, low cost and non-invasive nature. However, some problems exist in the process of breath test both for human exhaled vapor and the metabolites exhaled by lung cancer cells in vitro, such as the low concentrations of analytes and the complex matrix. Therefore, sample preconcentration is urgent before quantitative analysis by gas chromatography/mass spectrometry (GC-MS)Solid-phase microextraction (SPME) has become a powerful sample preparation method since introduced by Pawliszyn in the early 1990s, which combines sampling, extraction, pre-concentration and sample introduction in one step. Owing to its time-efficient, simplicity, solvent-free, field usable and linkup with detection instruments (SPME-gas chromatography, SPME-high performance liquid chromatography and SPME-capillary electrophoresis), SPME has been broadly applied in different fields, such as environment, food, forensics and pharmaceuticals. Considering the nature of analytes and the sample matrix, two fiber-SPME methods were developed based on two novel nanomaterial. Then it was coupled with GC-MS for the analysis of volatile organic compounds (VOCs) both in human exhaled vapor and the headspace gas of lung cancer cell culture in vitro. The main study contents are listed as follows:1. By a two-step anodic oxidization method, a highly ordered nanoporous anodic alumina coating was prepared on aluminum substrate. Based on the fiber, a facile and highly sensitive solid phase microextraction-gas chromatography/mass spectrometry method was developed for the analysis of volatile organic compounds in human exhaled breath vapor. To have a good knowledge of the fiber, some features were characterized and the results indicated that the coating had several advantages, including excellent chemical and thermal stability, high mechanical strength, large surface area and good extraction performance. In addition, some parameters related to extraction efficiency were also studied. Under the optimized conditions, the coating was used to quantitatively extract volatile organic compounds. Good linearity and wide linear range were obtained with correlation coefficients (R2) ranging from 0.9933 to 0.9999. The limits of detection of benzene homologues, aldehydes and ketones were between 0.7 and 3.4 ng L-1. Relative standard deviations (RSDs) (n=5) ranged from 1.8% to 15.0%. Finally, the developed method was successfully applied for the analysis of volatile organic compounds in human exhaled vapor samples of lung cancer patients and the controls, and the t-test was also carried out. Satisfied recovery (89%-115%) was obtained at two concentration levels. It provides a potential tool for rapid detection of volatile organic compounds in human exhaled breath.2. For the first time, we fabricated a new Fluoride graphite/Polyaniline (FG/PAIN) SPME fiber coating on a stainless steel wire by electrodeposition technology. Based the fiber, a simple, rapid, low-cost and sensitive solid phase microextraction-gas chromatography/mass spectrometry (SPME-GC/MS) method was proposed and validated for the analysis of VOCs in human exhaled vapor and the metabolites exhaled by lung cancer cell in vitro. Some features of fiber coating including morphology, lifetime, mechanical and thermal stability were studied. Parameters related to extraction and desorption performance were optimized systematically. Finally, the developed method was applied for the quantitative analysis of VOCs in human exhaled vapor (lung cancer patients and the healthy volunteers) and the metabolites exhaled by lung cancer cell in vitro. The R2 ranged from 0.9974 to 0.9999. The LODs with signal-to-noise ratio of 3 (S/N=3) were from 0.4 to 1.6 ng L-1. The RSDs were obtained at three spiked concentration levels, varying from 1.1% to 19.8%. The recoveries of the spiked breath samples at two concentration levels (0.5?g L-1 and 5?g L-1) were between 81% and 115%. It provides a new possibility to the determination of VOCs of exhaled breath both in vivo and in vitro.