A Research On The Measurement Techniques For The Content Of Organic Components In Gasoline

Crude Oil is an important kind of non-renewable eneries,accounting for 17.5% of primary energy consumption in China.The quality of gasoline is related to the safety of motor vehicles and environmental pollution.In this study,the metrology of the content of alcohols and ethers in gasoline is invsestigated.And the certified reference materials(CRMs)of mixed solution with alcohols and ethers are developed to meet the requirements for instrument calibration during the measurement of oxygen content of gasoline according to the national standard method of SH/T 0663.The main results of this work are shown as follows:Firstly,a methodology for the purity determination of organic bulk substances including alcohols and ethers is established.Two methods with different principles including Gas Chromatography(GC)method and Differential Scanning Calorimetry(DSC)method are employed to determine the content of organic impurities in bulk substances.The water content is determined by both Gas Chromatgraphy-Mass Spectrometry(GC-MS)and Karl Fischer coloumetric respectively,according to the principle of mass balance,the purities of alcohols and ethers are calculated based on the contents of organic impurities and water.Furthermore,the quantitative nuclear magnetic resonance(QNMR)is employed to determine the purity of n-propanol as a supplement at method.Among them,the GC normalization method is improved by adding the internal standard in both the bulk substance and its dilute solution.Assuming that the main component and the impurity response factor are equal,the total content of the impurities is determined.The improved normalization method is not affected by the nonlinear response of the FID detector.The impurity content is independent of the injection volume.The results are reproducible that the relative standard deviations of the purities of 13 kinds of alcohols and ethers are no more than 0.02%.The DSC was employed to determine the purity of alcohol with low melting point for the first time and the relative standard deviations are no more than 0.15%.Secondly,the apparatus and method for the preparation of the CRMs of mixed solution of volatile organic substances are invented.In order to ensure the accuraty of the prepared value of volatile component,volatile organic compounds are sealed in ampoules and then added into the mixed solution.When the mixed solution is continuously dispensed,in order to avoid the volatile components in the mother liquor to reach the headspace of the containerand and to ensure the content of each component in the CRM homogeneous,the air is rinsed by a mixed solution whose composition is same to the mother liquor before the introduction into the container.The results of full-scan and selected ion record and GC results show that the content of each components of the mixed solution are close to the prepared value.The recovery is in the range from 98.24% to 107.33%.The certified values are accurate and reliable.It is of great reference significance for the preparation and dispensing of volatile organic reference materials,mixed solution reference materials and moisture reference materials.In summary,the CRMs of the mixed solution of alcohols and ethers have been prepared,and the content of each alcohol and ester has been determined through the purity of bulk substances and prepared value of the gravimetry.New methods such DSC and QNMR are used to determine the purity of bulk alcohols and ethers.