Ion chromatography of phytate in roots and tubers.

The ion chromatographic method for the quantification of phytate (InsP(6)) in foods was adapted for the analysis of roots and tubers. To maximize sensitivity, ultraviolet (UV) detection following postcolumn derivatization was compared with evaporative light-scattering detection (ELSD). Detection limits for phytate were 0.5 and 1 microg for UV and ELSD, respectively. Unidentified peaks eluting close to and after InsP(6) were removed by solid-phase extraction. Phytate was detected in 11 of 15 roots or tubers. The highest phytate levels were 0.169 and 0.133% of the fresh weight of taro (Colocasia esculenta) and yuca (Manihot esculenta), respectively. Potatoes (Solanum tuberosum) contained 0.035-0.073% phytate, whereas no phytate at a detection limit of 0.003% of fresh weight was observed in sweet potatoes (Ipomoea batatas).