Analysis Of Edible Vegetable Oil By Surface Desorption Atmospheric Pressure Chemical Ionization Mass Spectrometry

A novel surface desorption atmospheric pressure chemical ionization source (DAPCI) was combined with the advantages of both atmospheric pressure chemical ionization (APCI) and desorption electrospray ionization (DESI), without any sample pretreatment, and a variety of surface adsorbed trace volatile and non-volatile substances can be detected. In this thesis the edible vegetable oil as the research object, which was analyzed and identified by self-developed surface desorption atmospheric pressure chemical ionization mass spectrometry (DAPCI-MS) method combined with principal component analysis (PCA). The main contents of the thesis are as follows:1. In this article, the sample introduction system, ionization source, mass analyzer and the detector of the mass spectrometer were overviewed. And the background, principles, equipment construction, development and the application of the surface desorption atmospheric pressure chemical ionization source were described. The design of the instrument from experimental equipment to the ideal intelligent instruments was discussed systematically. The performance and application of the products from different stages in the development of a commercial ion source were showed.2. Under the optimized experimental conditions, DAPCI has been established to get the fingerprint of edible vegetable oil samples directly without any sample pretreatment. Only signals of interest were identified using multiple-stage tandem mass spectrometry experiments, such as the major composition of oleic acid, palmitic acid in edible vegetable oil, which made DAPCI-MS attractive method for fast, small amount and pollution-free analysis of complex samples.3. Mass spectral fingerprints of edible vegetable oil were rapidly recorded using surface desorption atmospheric pressure chemical ionization mass spectrometry. DAPCI-MS fingerprints of edible vegetable oil were processed and analyzed using principal component analysis (PCA). Mass spectral fingerprint database of edible vegetable oil was preliminary established, and the identification and evaluation of the quality, origin, species, adulteration of oil samples, such as edible oil and non edible oil (tea seed oil and waste oil), tea seed oil from different areas, soybean oil from the same brand, rapeseed oil and cooking oil, tea seed oil mixed with different volume fraction of 1%,5%,30%,45%,60%of the waste oil were completed by chemometric model and calculation software.The results show that in the negative ion detection mode, different kinds of edible vegetable oil were rapidly detected by DAPCI-MS. DAPCI-MS combined with PCA approach was an useful analytical tool for differentiation of different types of oil products, which made DAPCI-MS attractive for fast, high-throughput, online, pollution-free analysis of complex samples. The relative standard deviation of signal strength of oleic acid in edible vegetable oil was 6.89%(n=11). The mean analysis time for a single sample was about 20 s, which was particularly suitable for rapid detection of bulk samples.