The Determination of Folic Acid (Pteroylmonoglutamic Acid) in Fortified Products by Reversed Phase High Pressure Liquid Chromatography

A reversed phase HPLC method was developed for the separation and determination of pteroylglutamic acid (PGA) in fortified foods. Extraction was carried out by heating with phosphate-citrate buffer, pH 8.0 containing ascorbate, and incubation with papain at 40°C for 4 hrs. The extracts were purified and concentrated on a short DEAE column which was rinsed with phosphate buffer, pH 7.0, of increasing molarity. PGA was eluted with 0.1M phosphate buffer, pH 7.0, containing 0.5M NaCl. The eluants were chromatographed on a Spherisorb ODS 10 μm column (250 × 4.6 mm) using a 30 min linear gradient of 2% to 30% acetonitrile in 0.1M acetate buffer, pH 4.0, at 1 ml/min and an absorbance detector at 280 nm. The coefficients of variation on analysis of 8 replicate samples of a milk and soy protein based infant formulas were 5.9% (at 4.6 ng/50 μl inject) and 6.8% (at 1.8 ng/50 μl inject) respectively.