title: Determination of the fatty acid profile of neutral lipids, free fatty acids and phospholipids in human plasma.
abstract: BACKGROUND
  Knowledge of the fatty acid composition of lipid classes in human plasma is an important factor in the investigation of human metabolism. Therefore, a method for the analysis of neutral lipid (NL), phospholipid (PL) and free fatty acids (FFA) in human plasma has been developed and validated.
  
  
  METHODS
  Separation of lipid classes was carried out by solid phase extraction of the lipid extract. The fractions were transesterified and the resulting fatty acid methyl esters were determined by GC/FID. For the method to be validated, precision, detection and quantification limits, as well as recovery, were determined for combined lipid extraction, solid phase extraction and GC analysis.
  
  
  RESULTS
  The lipid extraction was miniaturized and simplified by application of an ultrasound ‘Sonotrode’. The resolution of lipid classes was optimized with appropriate standards added to a representative plasma sample. In addition, a rapid derivatization procedure using trimethylsulfoniumhydroxide was established. Low determination limits (1.5, 0.2 and 1.3 μg/g plasma for NL, PL and FFA, respectively) indicate that the method’s sensitivity is sufficient to quantify even minor components. Furthermore, recovery for NL and PL fatty acids was found to range from 80% to 110%. The results were similar for FFA apart from more polar free fatty acids due to their higher solubility in water. Repetitive measurements showed very good precision apart from the long chain PUFA for which the coefficients of variation were significantly higher.
  
  
  CONCLUSIONS
  The present method is applicable to the quantitation of fatty acids in lipid classes of human plasma including several minor components.
authors.affiliation: Bioanalytik Weihenstephan, Research Center for Nutrition and Food Sciences, Technische Universität München, Freising, Germany.
authors.forename: Nina
authors.initials: N
authors.lastname: Firl
authors.forename: Hermine
authors.initials: H
authors.lastname: Kienberger
authors.forename: Teresa
authors.initials: T
authors.lastname: Hauser
authors.forename: Michael
authors.initials: M
authors.lastname: Rychlik
mesh_terms: D005230:Fatty Acids, Nonesterified / Q000097:blood* / Q000302:isolation & purification / Q000592:standards; D005231:Fatty Acids, Unsaturated / Q000097:blood / Q000302:isolation & purification / Q000592:standards; D008401:Gas Chromatography-Mass Spectrometry / Q000592:standards; D006801:Humans; D006878:Hydroxides / Q000737:chemistry; D010743:Phospholipids / Q000097:blood* / Q000302:isolation & purification / Q000592:standards; D017680:Potassium Compounds / Q000737:chemistry; D012015:Reference Standards; D052616:Solid Phase Extraction
chemical_list: D005230:Fatty Acids, Nonesterified; D005231:Fatty Acids, Unsaturated; D006878:Hydroxides; D010743:Phospholipids; D017680:Potassium Compounds; C029943:potassium hydroxide