Determination of Free Glycerol in Biodiesel Using UV-Visible Spectroscopy: a Validation Study

What is it about?

High glycerol content in biodiesel impairs engine performance. Brazilian legislation, (ANP Resolution 45/2014), limits the maximum of 0.02 % w/w for free glycerol in biodiesel. The ASTM D6584 standard method for glycerol determination is gas chromatography, a time consuming and expensive technique. As alternative, free glycerol in biodiesel can be determined, after derivatization, by absorption spectroscopy in the visible region (410 nm). In this work, we have used a validation protocol for the spectroscopy method. Results indicate that the proposed method is linear (r 2 = 0.995) for the studied concentration range and has acceptable accuracy and precision. The method presented relative standard deviations values of intermediate repeatability and accuracy below 5.0 %.

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