Ambient Mass Spectrometry For Direct Analysis Of Diethyl Phthalate In Perfume And Soil

Phthalic acid esters(PAEs) can induce ecological imbalance and toxic effect to human health. Various PAEs with different function are detected in crops, medicines, food,beverages and cosmetics; the illegal use of PAEs has threatened human health. Diethyl phthalate(DEP) is the most common restricted or prohibited ingredient in the test reports for various products and environment. In this paper, two kinds of emerging direct ionization methods extractive electrospray ionization(EESI) and surface desorption atmospheric pressure chemical ionization(SDAPCI) are applied to the analysis of perfume and soil samples. The content, distribution and desorption/adsorption behavior of DEP are all studied.Firstly, the general physico-chemical nature and application of DEP are briefly elabotated. The advantages and result of some commonly analytical methods for the analysis of DEP in perfumes and soil are summarized. The basic working principle of EESI and SDAPCI and their applications for different sample are sketched. Based on the above brief overview, the main contents of this thesis are as follows:1. The EESI-MS technique was applied for the qualitative and quantitative analysis of the illegal additive DEP in five different brands perfume purchased from local market.Firstly, the standard DEP solution sample was analyzed by collision-induced dissociation(CID) experiments in order to verify the validity of EESI-MS2 method for detection of DEP.Then the characteristic fragment m/z 177 was used to do quantitative determination and obtained a better linearity, precision, limit of detection and quantity. On this basis, the EESI technique was applied for the analysis of five different brands perfume actual samples. The results showed that all five samples containing illegal additive DEP, the relative standard deviation was 0.06 %~3.4 %, the recovery was 93.7 %~95.7 %. The method has many advantages such as high sensitivity, with no use of a large quantity oftoxic chemicals. The study showed that, EESI-MS technique is suitable for the trace analysis of analytes in the bulk samples, and expected to apply to the detection for the PAEs in other complex matrix cosmetics, green, safe and environment-friendly.2. To address the widespread contamination of surface soil by PAEs, the SDAPCI-MS imaging was successfully applied for the direct determination of diethyl phthalate(DEP) in soil without any pretreatment. The precursor ion, protonated diethyl phthalate(m/z 223),was confirmed by CID experiments to exclude false-positive results. The protonated DEP(m/z 223) and the characteristic fragment(m/z 177) were used to obtain the distribution of DEP molecules in the soil using imaging mass spectrometry. The two ion images without any pretreatment showed that the distribution of DEP was inhomogeneous in the shape of clusters, but DEP was transfered after adding deionized water evenly into the surface of soil. The spatial resolution and the analysis speed per pixel were 0.25 mm2, and 4.5 s. This new method may be applicable for the study of content and distribution of PAEs in other complex solid samples.3. The effects of coffee on desorption and adsorption behavior of DEP in surface soil was studied by using the SDAPCI tandem mass spectrometry imaging technique. And the mass spectrometry images were identified by ESI-MS. The SDAPCI-MS and MS/MS images with m/z 223 and 177 were obtained for three soil samples after adding different solution: DEP standard solution, coffee solution, mixed solution of DEP and coffee. From the comparison among the mass spectrometry images we find that coffee can facilitate DEP desorption, increase their dispersion degree and reduce the unevenness level.Furthermore, coffee can enable the DEP which dissolved in the liquid phase mainly recrystallize on the solid soil surface. In addition, the ESI-MS results of soil in different mass spectrometry imaging area were consistent with the SDAPCI-MS images. This method can provide a valid reference for the environmental assessment of the food processing industry, the degradation of DEP in environment and other issues.