Accelerated solvent extraction for quantitative measurement of fatty acids in plasma and erythrocytes

Consumption of fish rich in n-3 highly unsaturated FAs (i.e., EPA and DHA) has been suggested to decrease the risk of lifestyle-related diseases such as coronary heart disease, cancer, diabetes, and dementia. Blood levels of those FA are known appropriate biomarkers of both the corresponding dietary FA intakes and fish consumption. In place of traditional handwork methods for extracting FA, we performed an accelerated solvent extraction (ASE) for at least 13 selected FA in plasma and erythrocytes to measure them by GLC. The FA levels (concentrations and compositions) in 35-50 microL of plasma or erythrocytes were extracted by ASE and measured by GLC. Intra- and interassay coefficients of variation were < or = 6.0% for both blood materials, except with a minor group of FA (< or = 1.0% of total FA). When ASE was compared with two traditional handwork methods, FA levels in plasma from 18 healthy subjects were all coincident with very high Pearson's correlation coefficients for the three sets of the same 18 samples (r > or = 0.85 to 0.95, P < 0.0001), except for 18:0 (r = 0.59, P < 0.01). Using ASE and GLC, we have developed a new method for determination the levels of FA in plasma and erythrocytes as biomarkers for dietary intake of fish, fat, and FA. This new method makes it feasible to measure small volumes of samples, automatically, quantitatively, routinely, easily, rapidly and cheaply, with acceptable precision and accuracy.