两种pH值法测定玫瑰花花色苷含量的比较

Comparison of Two pH Methods for Determining Anthocyanins from Flower Petals of Rose

采用单一pH法和pH示差法对玫瑰花中花色苷含量的测定进行比较,通过对两种方法的测量差异分析,确定它们的适用条件。结果表明,为减小测量误差,选用pH示差法时,吸光度不应低于0.2,稀释液吸光度在0.27时误差较大;选用单一pH法时,应将色素溶液稀释至3.5～13.8mg/L质量浓度范围内。单一pH法受溶剂浓度影响较大,使用该法测定时,应在同一溶剂中测定。

Anthocyanin from flower petals of rose was assayed by single pH method at pH 1.0 and pH differential method at pH 1.0 and pH 4.5. Anthocyanin concentrate was obtained from dried flower petals of rose by extraction with 60% acidic ethanol solution, low-temperature vacuum concentration, and purification by sequential extraction with acetone and ether followed by AB-8 macroporous resin adsorption prior to determination. For reducing measurement error by the pH differential method, the anthocyanin concentrate should not be diluted to absorbance values at 518 nm below 0.2, and a big error was found at an absorbance value of 0.27. When determined using the single pH method, and the anthocyanin concentration should be controlled in the range from 3.5 to 13.8 mg/L. Single pH method was easily affected by the solvent concentration, and thus the determination by this method should be carried out using the same solvent.