Quantitative determination of plasma c8-c26 total fatty acids for the biochemical diagnosis of nutritional and metabolic disorders.
We have developed a capillary gas chromatography-electron-capture negative-ion mass spectrometry (GC/MS) method for the quantitative determination of C8-C26 total fatty acids in plasma. Following hydrolysis, hexane extraction, and derivatization with pentafluorobenzyl bromide, fatty acid esters are analyzed in two steps: a splitless injection and a second, split injection (1:100) for the quantitation of the more abundant long-chain species. Fourteen saturated and 25 unsaturated fatty acids are quantified by selected ion monitoring in ratio to 13 stable-isotope-labeled internal standards. Calibrations exhibit consistent linearity and reproducibility. Intraassay (n = 17) and interassay (n = 12) CVs ranged from 2.5 to 13.2% and from 4.6 to 22.9%, respectively. Recoveries ranged from 76 to 106%. Reference ranges were established for four age groups (<1 month, 1 month to 1 year, 1-17 years, >18 years) and compared to specimens from patients with nutritional deficiency of omega-3 and omega-6 polyunsaturated fatty acids, inborn errors of mitochondrial fatty acid oxidation, and peroxisomal disorders. Retrospective evaluation of the concentration of linoleic acid in 35 cases with a diagnosis of essential fatty acid deficiency previously made by gas chromatographic analysis with flame ionization detection (GC/FID) found a specificity and sensitivity of only 55 and 50%, respectively, for the GC/FID method when compared to GC/MS.
Lagerstedt
S A
SA
Biochemical Genetics Laboratory, Mayo Clinic and Foundation, 200 First Street SW, Rochester, MN 55905, USA.
Hinrichs
D R
DR
Batt
S M
SM
Magera
M J
MJ
Rinaldo
P
P
McConnell
J P
JP
D000293:Adolescent; D001692:Biological Transport; D002648:Child; D002675:Child, Preschool; D005227:Fatty Acids / Q000097:blood* / Q000378:metabolism; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008659:Metabolic Diseases / Q000097:blood* / Q000175:diagnosis; D008928:Mitochondria / Q000378:metabolism / Q000473:pathology; D009748:Nutrition Disorders / Q000097:blood* / Q000175:diagnosis; D010084:Oxidation-Reduction; D012016:Reference Values
D005227:Fatty Acids