Microwave Energy Increases Fatty Acid Methyl Ester Yield in Human Whole Blood Due to Increased Sphingomyelin Transesterification
- Author(s): Metherel, AH
- Aristizabal Henao, JJ
- Ciobanu, F
- Taha, AY
- Stark, KD
- et al.
Published Web Locationhttps://doi.org/10.1007/s11745-015-4053-5
© 2015 AOCS. Dried blood spots (DBS) by fingertip prick collection for fatty acid profiling are becoming increasingly popular due to ease of collection, minimal invasiveness and its amenability to high-throughput analyses. Herein, we assess a microwave-assisted direct transesterification method for the production of fatty acid methyl esters (FAME) from DBS. Technical replicates of human whole blood were collected and 25-μL aliquots were applied to chromatography strips prior to analysis by a standard 3-h transesterification method or microwave-assisted direct transesterification method under various power (variable vs constant), time (1-5 min) and reagent (1-10 % H2SO4in methanol) conditions. In addition, a standard method was compared to a 5-min, 30-W power microwave in 1 % H2SO4method for FAME yield from whole blood sphingomyelin, and sphingomyelin standards alone and spiked in whole blood. Microwave-assisted direct transesterification yielded no significant differences in both quantitative (nmol/100 μL) and qualitative (mol%) fatty acid assessments after as little as 1.5- and 1-min reaction times, respectively, using the variable power method and 5 % H2SO4in methanol. However, 30-W power for 5 min increased total FAME yield of the technical replicates by 14 %. This increase appears largely due to higher sphingomyelin-derived FAME yield of up to 109 and 399 % compared to the standard method when determined from whole blood or pure standards, respectively. In conclusion, microwave-assisted direct transesterification of DBS achieved in as little as 1-min, and 5-min reaction times increase total fatty acids primarily by significantly improving sphingomyelin-derived fatty acid yield.
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