Low-Cost 3D-Printed Reactionware for the Determination of Fatty Acid Content in Edible Oils using a Base-Catalyzed Transesterification Method in Continuous Flow

A Du Preez,E Smit,R Meijboom

doi:10.1007/s12161-022-02233-2

Abstract

A low-cost flow system was designed, manufactured, and tested to perform automated base-catalyzed transesterification of triacylglycerols to determine the fatty acid content in edible oils. In combination with traditional gas chromatographic analysis (GC-FID), this approach provides a semi-automated process that requires minimal manual intervention. The main flow system components, namely syringe pumps, connectors (i.e., flangeless fittings), and reactors, were manufactured using 3D-printing technology, specifically fused deposition modeling (FDM). By fine-tuning 3D-printer settings, high-quality leak-tight fittings with standard threading were manufactured in polypropylene (PP), which reduced the overall cost of the flow system significantly. Due to the enhanced reactivity in flow, lower catalyst concentrations (≤ 1.5 wt.%) were needed compared to traditional batch reactions (5 wt.%). The suitability of the automated flow method was determined by comparing results with the certified fatty acid content in sunflower seed oil from Helianthus annuus. Acceptable levels of accuracy (relative errors < 5%) and precision (RSD values ≤ 0.02%) were achieved. The mostly 3D-printed flow system was successfully used to determine the fatty acid content of sunflower and other commercial edible oils, namely avocado oil, canola oil, extra virgin olive oil, and a canola and olive oil blend. Linoleic acid (C18:2) was the major component in sunflower oil, whereas all other oils consisted mainly of oleic acid (C18:1). The fatty acid content of the edible oils was comparable to certified and literature values.

Highlights

Analytes are often derivatized to increase volatility and reduce polarity, making them more amenable to gas chromatographic analysis
This compatibility leads to a significant advantage because damaged or misplaced pieces can be replaced at lowcost, or the complete self-manufactured kit can be used on its own
The versatility and cost-saving capabilities of 3D-printing technology were demonstrated by reproducing an expensive flangeless fittings kit consisting of syringe adapters, flangeless nuts, male Luers, unions, and mixers that are often used in continuous flow systems

Summary

Introduction

Analytes are often derivatized to increase volatility and reduce polarity, making them more amenable to gas chromatographic analysis. The determination of the fatty acid content of edible oils by the derivatization of triacylglycerol molecules to glycerol and its corresponding three fatty acids (Tammekivi et al 2019) is common practice (de Koning et al 2001). Edible oils consist primarily of palmitic (C16:0), stearic (C18:0), oleic (C18:1), linoleic (C18:2), and linolenic (C18:3) acids. These five major fatty acids determine the physical and. Analytes are derivatized manually (i.e., offline), and many methods have been developed to make this process more reliable and reproducible (Tammekivi et al 2019)

Methods

Results

Conclusion