Determination of Docosahexaenoic Acid in Human Serum and Milk by Capillary Gas Chromatography

Objective:To establish a simple and reliable method for the determination of serum and milk doˉcosahexaenoic acid(DHA)by capillary gas chromatography.Methods:DHA were transesterified with methanol_toluene_acetyl chloride at100℃.The separation was performed with a gas chromatography equipped with a flame ionization detector.A fused_silica column coated with biscyanopropyl polysiloxane was used.The quantification of DHA was based on an internal standard(C 15:00 )and on calibration standards.Results:The within_day and between_day coefficient of variation was1.5%～4.7%and5.5%～8.5%for serum,3.6%and1.8%for milk,respectively.The mean recovery rate was91.6%.A good linear relationship between the peak area ratios and concentration was found at DHA concentration ranged from10to250mg/L(r=0.9994).Conclusion:The method is simple,accurate,and suitable to clinical application.