Visual method and colorimetric method are generally used for oil chroma. But direct visual observation is subjective and of low accuracy and sensitivity. Changing color film or color solution frequently is tedious. In this article a new method taking on a conventional spectrophotometer for measuring the chroma of petroleum products, namely Spectrophotometry, is introduced. By preparing 25 kinds of standard color solution are prepared; a standard curve is worked out; and a suitable absorption wavelength is found, then an appropriate cuvette is chosen to make the absorbance fall between 0.1 and 1.0. The relational table of the absorbance of different wavelengths and color is set. Oil chroma values can be obtained directly from the table. It also can be calculated by curve fitting equation. The spectrophotometry not only improves the accuracy and sensitivity of the chroma, but also can be used for a long-term with simple operation.%石油产品色度测定通常采用目测比色法和比色计法，但是直接目视观测主观性较强，准确度和灵敏度都较低，并且要定期更换比色片或比色液，步骤繁琐.文中研究了一种采用普通分光光度计就能对石油产品色度进行测定的新方法，即分光光度法.该方法通过配制25种标准比色液，然后做出标准曲线，寻找合适吸收波长，然后选用合适的比色皿，使得吸光度落在0.1~1.0之间，建立了不同波长下的吸光度和色度的关系表，可以通过查表直接得到石油产品色度值，也可以通过拟合的曲线公式计算出色度值.分光光度法不仅提高了测定色度的准确度和灵敏度，同时操作简单可以长期使用.
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