Application Of Gas Chromatography-Mass Spectrometry In The Determination Of Environmental Organic Pollutants

As much attention is paid to environmental pollution and food safety, the legislations for organic pollutants are increasingly stringent. The corresponding detection techniques become sophisticated. Therein, the gas chromatography-mass spectrometry (GC-MS) as a mature means of testing not only shows a high separation capability of chromatography, but also combines mass spectrometry's accurate identification advantages. GC-MS can be used for qualitative and quantitative analysis, especially for detecting micro or trace amount of organic pollutants in samples. For a long time, GC-MS has always been the most commonly used tool to analyze complex unknown substance in environment, which has become a hot research issue of the environmental protectors.With the development of sample pre-treatment and injection technology, the sensitivity of GC-MS has been continuously improved. However, there are still some shortcomings for this technology. For instance, the gas, liquid or solid compounds that they analyzed should be stable during the operating temperature. Furthermore, the gasification temperature of the liquid or solid samples must be lower than the operating temperature. These problems brought some restrictions to the application of GC-MS, which needs to be solved in order to provide a convenient and accurate determination method for the analysis of environmental organic pollutants.In the present work, three GC-MS methods were developed in order to obtain in-depth understanding of the distributions of some typical organic pollutants in environmental water, cosmetic and decorative paint samples, which can provide a basis for regulations and pollution control. They are as follows:(1) For purpose of decreasing injection errors caused by the external standard method, a GC-MS internal standard method has been proposed for simultaneous determination of the three isomers of phenylenediamine, which is extracted by liquid-liquid extraction in hair dyes. The phenylenediamines were extracted with ethyl acetate, cleaned up by centrifugation and analyzed by GC-MS using naphthalene as the internal standard. The completely separated peaks were identified by MS and quantified by selected ion monitoring mode. The correlation coefficients are 0.9970 ~ 0.9993 in the range of 5.0 ~ 500μg/mL. The obtained average recoveries of phenylenediamines are from 81.01 to 115.32 %. The precision of the method, which is indicated by the relative standard deviations (RSD), are within the range of 4.98 ~ 18.67 %. The detection limits based on signal-to-noise ratio (S/N = 3) are within the range of 0.5 ~ 2.0μg/mL. These data demonstrated that the proposed method was suitable for identification and quantitation of the phenylenediamines in hair dyes.(2) A high-sensitivity method for simultaneously analyzing the six benzene series compounds contained in oil paints by GC-MS with the chlorobenzene as the internal standard was proposed. The chromatographic separation condition, extraction solvents, quantitative method and the selection of internal standard were optimized. The linear correlation coefficients of benzene, toluene, ethylbenzene and dimethylbenzenes are all larger than 0.995, which show good linear relativity in the range of 1.0 ~ 500.0μg/mL. When the concentration is in the range of 100.0 ~ 250.0μg/mL, the recoveries are 85.01 ~ 107.44 % and the RSD are 2.58 ~ 12.43 %. The minimum detection limits based on signal-to-noise ratio (S/N = 3) are 0.002 ~ 0.05μg/mL. The proposed method exhibited a high sensitivity and could meet the need of actual oil paint analysis.(3) An effective method, which included solid phase extraction, nitrogen blowing concentration, derivatization and gas chromatography-mass spectrometry technology, was developed to determinate the environmental endocrine disruptor--octylphenol. Parameters relevant to the extraction performance and detection sensitivity, such as water sample pretreatment method, solid-phase extraction column type, extraction rate, derivatization reaction time, chromatographic separation condition and monitoring ions were studied. The distributions of octylphenols in Jinan Daming Lake were investigated using the proposed method. The average concentration of octylphenol is 23.18 ng/L. This indicates that the water has been polluted to some extents. In addition, the contents of octylphenol in different sampling sites differ significantly, with a lowest concentration of 6.93 ng/L and a highest concentration of 41.56 ng/L, which can be attributed to the low ability of floating and diffusion. These data provide scientific references for government to make decisions on pollution prevention and ecological risk assessment.