Abstract: A comparative study on the determination of chlorine in gasoline was carried out, and a total of 51 laboratories reported their testing results. The results of chlorine content were analyzed by frequency distribution statistics and robust Z-ratio statistics. The results showed that there was little difference between the arithmetic mean and the median value of each sample, and the distribution of results was symmetrical. The frequency distributions of the results were approximately normal. Two methods were used in the comparative study: X-ray fluorescence spectrometry and oxidative microcoulometry. There was no significant difference between the arithmetic means of the two methods. X-ray fluorescence spectrometry has the characteristics of simple operation, fast analysis speed, high precision and good stability, and the deviation of the results was smaller than that of oxidative microcoulometry in this comparative study. The overall satisfaction rate of Z-score evaluation was 88.2%, which indicated that the detection level of related laboratories was high and could provide reliable support for the detection of chlorine content in petroleum products.

Key words: test comparison, chlorine content, X-ray fluorescence spectrometry, oxidative microcoulometry, robust statistics