Determination of docosahexaenoic acid in infant formulas with gas chromatography

Objective: Docosahexaenoic acid (DHA) is important for the development of infant’s nervous and visual system because it is a major fatty acid in brain and retina phospholipids. However, the benefit of adding DHA in infant formulas is still controversial. The over intake of DHA should be considered because of its side effect. The aim of this study was to get a valid analysis method of DHA using gas chromatography (GC) to determine the concentration of DHA in infant formula. Method: The milk fat was extracted in chloroform-methanol (1:2), continued with methylated in methanol-toluene (4:1) with acetyl chloride, and finally, injected to GC. Result: The GC conditions were as follows: Injector temperature was 230°C, detector temperature was 250°C, oven temperature was programmed to increase from 130°C to 230°C by 2°C/min and held for 20 min, helium flow rate was 2.00 ml/min, and split ratio was 1:3. This method had passed the precision and recovery evaluation. The result of DHA determination in five infant formula samples was 27.49±0.62 mg/100 g, 31.14±0.43 mg/100 g, 11.83±0.38 mg/100 g, 19.34±0.58 mg/100 g, and 45.87±0.42 mg/100 g. Conclusion: The method was valid and successfully applied to determine of DHA in infant formula.