Organic acids and alcohols quantification by HPLC/RID in sugarcane vinasse: analytical method validation and matrix effect assessment

ABSTRACT

The composition of sugarcane vinasse varies according to the substrate of alcoholic fermentation, e.g. if it is sugarcane juice and/or molasses. Regardless of the origin, the main organic compounds found in sugarcane vinasse are organic acids, alcohols and a low amount of carbohydrates. To access the organic composition of such wastewater, the present paper describes a high-performance liquid chromatography (HPLC) separation method coupled to a Refractive Index Detector (RID) in order to quantify the organic acids (C1 to C6) and alcohols in sugarcane vinasse. The analysed substances were acetic acid, butyric acid, caproic acid, citric acid, lactic acid, propionic acid, succinic acid, valeric acid, butanol, ethanol, glycerol and methanol. A validation study of the method was performed taking into account the matrix effect exerted by vinasse samples in natura. In conclusion, it was proved that the method is suitable for assessing the organic composition of vinasse: able to separate 12 analytes, with excellent linearity (R² > 0.999), with adequate working ranges, high precision (recovery ranging from 83% to 102%), and low matrix effects (<5%).

KEYWORDS:

• Liquid chromatography
• organic acids
• standard addition method
• analytical validation
• vinasse composition
• wastewater characterisation

Acknowledgments

The authors are grateful to Petrobras and ANEEL for the financial and technical support and to the ethanol mill facility for supplying the sugarcane vinasse. The authors would also like to thank Luciana Yumi Watari, Wiviane Cristine de Paulo and Weslei Mateus Sallaroli de Mello for their significant contribution to this work.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary material

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Correction Statement

This article has been republished with minor changes. These changes do not impact the academic content of the article.