Determination of Nutritional and Cyclopropenoid Fatty Acids in Cottonseed by a Single GC Analysis

Abstract

Historically, a complete analysis of cottonseed fatty acids required two separate analyses: gas chromatography (GC) for nutritional fatty acids and a separate analysis for cyclopropenoid fatty acids (CPFA). Using base esterification and optimized GC conditions, the method presented combines both analyses into a single GC procedure that improves analytical processes and streamlines workflow. While there were challenges, the resolution of critical pairs malvalic/stearic and dihydrosterculic/alpha linolenic methyl esters were adequately separated, allowing for accurate quantitation. Single lab reproducibility measurements (RSD) for major nutritional fatty acids ranged from 0.7 to 2.0 %. For CPFA the RSD ranged from 1.1 to 5.4 %, with the higher variability seen in the extracted cottonseed. In oils, the precision was similar between nutritional fatty acids and CPFA at equivalent concentrations, indicating the variation comes from the extraction process. Average spiked recovery results ranged from 93.3 to 106.5 % for selected fatty acids. In addition, complete fatty acid profile results compare favorably with other methodologies and historical data, demonstrating that it is possible to combine two legacy methods into one.