title: Microwave Energy Increases Fatty Acid Methyl Ester Yield in Human Whole Blood Due to Increased Sphingomyelin Transesterification.
abstract: 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% H2SO4 in methanol) conditions. In addition, a standard method was compared to a 5-min, 30-W power microwave in 1% H2SO4 method 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% H2SO4 in 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.
authors.affiliation: Department of Kinesiology, University of Waterloo, 200 University Avenue, Waterloo, ON, N2L 3G1, Canada.
authors.forename: Adam H
authors.initials: AH
authors.lastname: Metherel
authors.forename: Juan J
authors.initials: JJ
authors.lastname: Aristizabal Henao
authors.forename: Flaviu
authors.initials: F
authors.lastname: Ciobanu
authors.forename: Ameer Y
authors.initials: AY
authors.lastname: Taha
authors.forename: Ken D
authors.initials: KD
authors.lastname: Stark
mesh_terms: D002849:Chromatography, Gas; D059788:Dried Blood Spot Testing / Q000379:methods*; D004952:Esters / Q000097:blood* / Q000737:chemistry; D005227:Fatty Acids / Q000737:chemistry*; D015525:Fatty Acids, Omega-3 / Q000097:blood; D005260:Female; D006801:Humans; D008297:Male; D008872:Microwaves; D013109:Sphingomyelins / Q000737:chemistry*
chemical_list: D004952:Esters; D005227:Fatty Acids; D015525:Fatty Acids, Omega-3; D013109:Sphingomyelins