Development Of Certified Reference Materials For Sulfur Content In Isooctane

Sulfur in gasoline can cause serious environmental problems and harm human health.Almost all countries have proposed increasingly strict in limitation of the amount of sulfur in gasoline.It is necessary to accurately determine the sulfur content in gasoline.It is of great significance to prepare reference material of sulfur in gasoline to control the quality of gasoline.In the experiment,the pre-treatment of samples was first treated.And the pre-treatment method of microwave acid digestion was used.The sampling methods,pre-digestion conditions and digestion conditions were investigated.It is concluded that the sampling quantity is 0.2 g,which can not only guarantee the accuracy of the measurement but facilitate the digestion.The pre-digestion can guarantee the complete digestion of oil samples.The use of microwave digestion instrument with high temperature and pressure in closed environment can effectively avoid pollution and loss.This dissertation firstly explored the accurate and rapid sulfur content analysis method in isooctane and measured different sulfur contents in isooctane samples using inductively coupled plasma mass spectrometry?ICP-MS?,the isotope dilution mass spectrometry?ID-ICP-MS?,inductively coupled plasma emission spectrometry?ICP-OES?and X-ray fluorescence spectrometry?XRF?,respectively.The experimental data show that results of the four methods agree with each other.In order to detect the reliability of the measurement results,the certified reference material of sulfur in gasoline were measured in accordance with the same experimental conditions.The experimental results show that the measured values are within the range of the certificate value,suggesting that the measurement results are accurate,reliable and reproducible.On the basis of isooctane,according to the standard of sulfur content in gasoline in national IV and V standard,the sulfur content reference material in isooctane was prepared and packed into the ampoule.The uniformity analysis,stability analysis and uncertainty evaluation of the two kinds of reference materials were determined.The sulfur content via ID-ICP-MS of the national IV standard and the national V standard isooctane is 50.41 mg·kg^-1 and 10.65 mg·kg^-1 respectively.15 bottles of reference materials were randomly selected for uniformity analysis via XRF.The uniformity of sulfur reference materials in both kinds of isooctane was good.The stability was tested by storing samples at room temperature for 0,1,2,3,6,9 and 12 months,respectively.It is proved that the sulfur content in both reference materials is stable by the measured values,and there is no obvious change.The expansion uncertainty is 1.36 mg·kg^-1 and0.63 mg·kg^-1,respectively.