离子色谱—柱后反应与分光光度联用法测定植物性食品中植酸的研究

Study on the Determination of Phytic Acid in Plant Foods by Ion Chromatography Combined with Postcolumn Reaction-Spectrophotometric Method

本文介绍一种离子色谱-柱后反应与分光光度法联用测定植物性食品中植酸含量的方法。样品经2％三氯乙酸萃取后,仅经微膜(孔径0.45μm)过滤一步处理。样液经阴离子浓缩柱富集植酸并排除杂质,然后进入阴离子交换柱进行分配分离,以0.24mol/1HNO_3为流动相,以0.77ml/Min的流速,将植酸洗提出来与柱后反应剂(0.02％FeCl_3-0.3％磺基水杨酸,呈紫红色)作用。,此时,试剂中的Fe^3-被植酸中的PO_4~3键合而去除,因而产生褪色现象,最后进入流通比色池在500nm下测定其消光负值。本研究采用标准加入法消除样品基体效应和系统误差,达到灵敏、精确测定的目的。方法的最低检测浓度为0.04mg/g;精密度(C.V.)为3.3～5.4％;一般样品的测定结果与比色法无显著差异,能灵敏、精确地测定多种植物性食品。

A method is described for the ion chromatographic determination of phytic acid in plant foods. After extraction with 2% trichloroacetic acid,the only sample preparation necessary is filtration through a membrane(pore size,0. 45μm). The sample solution is injected into an anion concentrated column for the collection of phytic acid and the removal of impurity. Separation is achieved on an anion-exchange column with 0. 24mol/L HNO3 as mobile phase at a flow rate of 0. 77ml/min. The phytic acid is reacted with postcolumn reagent (0. 02% FeCl3 containing 0. 3% sulfosalicylic acid,purple color),the iron in the reagent is bound by the phosphate in phytic acid and thus removed,resulting in a decrease in the intensely purple color. Finally,the decrease in color is measured at 500nm in flow cell. In this study,the matrix effect and systematic error are removed in use of the standard addition method. The minimum detectable concentration of this method is 0. 04mg/g;the precision (c. v. ) is 3. 3-5. 4%;Results for phytic acid in conventional samples determined by this method showed no significant difference with the results obtained by the colorimetric method. This method can be used for determination of phytic acid in many kind of plant foods with high sensitivity and accuracy.