[Determination of phytate and phosphate in plant samples by suppressed conductivity ion chromatography]

Determination of phytate and phosphate by suppressed conductivity ion chromatography was investigated. Plant samples were extracted with 1% (mass fraction) trichloroacetic acid (TCA). After centrifugal settling, the supernatant was filtered with a 0.45 microm filter membrane before injected into the ion chromatographic system and detected by suppressed conductivity. The gradient eluent was composed of 0.22 mol/L sodium hydroxide solution, water and 50% (v/v) isopropyl alcohol solution. Phytate and phosphate were determined within 15 min, and no interference was found in the presence of fluorate, chlorate, nitrate, sulphate and TCA. Good linearities for phytate and phosphate were obtained in the ranges of 5-400 mg/L (r2 = 0.9994) and 5-500 mg/L (r2 = 0.9999), and the detection limits (S/N = 3) were 3.5 mg/L and 1.5 mg/L, respectively. The average recoveries for phytate and phosphate were 99.8% and 98.4%, and their relative standard deviations were 1.98% and 2.09%, respectively.