Abstract
Palm oil is one of the major oils and fats produced in the world today. The quality of palm oil is crucial to be investigated, and one of the quality indices is free fatty acid (FFA) content. Therefore, in this study, an electrochemical approach for the determination of FFA has been explored as an alternative to replace the conventional method (titration method). The electrochemical method was developed based on electrochemically reduced graphene oxide (rGO) coupled with gold nanoparticles (AuNPs) deposited onto a screen-printed carbon electrode (SPCE) via drop-casting technique. The voltammetric behaviour of 2-methyl-1,4-naphthoquinone (VK3) in the presence of palmitic acid at the modified electrode was investigated in an acetonitrile/water mixture containing lithium perchlorate (LiClO4). The electrochemical detection of palmitic acid was based on the voltammetric reduction of VK3 to form the corresponding hydroquinone which is proportional to the concentration of palmitic acid. Under optimum conditions, the developed method showed a good linear relationship towards palmitic acid in the concentration ranging from 0.192 mM to 0.833 mM with the detection limit of 0.015 mM. The exploration of the developed system is expected to achieve high sensitivity and excellent selectivity towards the determination of FFA content in palm oil.
Highlights
The palm oil (Elaeis guineensis) originated in the tropical rain forest of Western Equatorial Africa and leads to an astonishing increase of plantation size throughout Southeast Asia [1]. 19.52 million tonnes of crude palm oil have been produced in Malaysia, making Malaysia the world second-largest producer of palm oil in the world [2]
An electrochemical method based on screen-printed carbon electrode (SPCE) modified reduced graphene oxide coupled with gold nanoparticles for the determination of free fatty acids (FFA) content in palm oil has been proposed
All Raman spectra depicted the same pattern of the curve, which implies that the structure of graphene was not affected when the reduction process of graphene oxide (GO) to reduced graphene oxide (rGO) and the addition of AuNPs onto rGO sheets take place
Summary
The palm oil (Elaeis guineensis) originated in the tropical rain forest of Western Equatorial Africa and leads to an astonishing increase of plantation size throughout Southeast Asia [1]. 19.52 million tonnes of crude palm oil have been produced in Malaysia, making Malaysia the world second-largest producer of palm oil in the world [2]. The traditional way for the determination of free fatty acids in palm oil is through the acid-base titration method by titration sample against potassium hydroxide in hot 2-propanol solution, and phenolphthalein is used as an indicator [14]. This method is direct and easy, it is encountered with some problems such as time-consuming, labour-intensive, and lack of accuracy [15]. An electrochemical method based on screen-printed carbon electrode (SPCE) modified reduced graphene oxide coupled with gold nanoparticles for the determination of FFA content in palm oil has been proposed. The principle of the determination is based on the electrochemical reduction of VK3 in an acetonitrile/water mixture containing lithium perchlorate (LiClO4) corresponding to concentrations of FFA
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