分光光度法测定叶绿素含量的提取液的适宜浓度

Evaluation of the optimum concentration of chlorophyll extract for determination of chlorophyll content by spectrophotometry

分光光度法是测定叶绿素含量的最常用方法之一,但是运用该方法所测得叶绿素含量往往随叶绿素提取液浓度的变化而波动,进而影响对叶绿素含量测定的准确性。因此,使用适宜浓度的叶绿素提取液浓度,对准确测定叶绿素含量至关重要。本研究为了探索问题,以枣树(Ziziphus jujuba)"金昌一号"叶片为材料,用乙醇和丙酮-乙醇混合液(1∶1)分别提取叶片叶绿素,将叶绿素提取液稀释成不同的浓度梯度,用分光光度法测定叶绿素含量。研究发现在叶绿素提取液浓度低于0.80cm2·mL^(-1)(或14.67mg·mL^(-1))时,所测得叶绿素含量趋于平稳,与Excel二次曲线拟合分析结果基本一致。这表明运用分光光度法测定枣树叶绿素含量的提取液适宜浓度应低于该浓度。而且还发现吸光度(A)比值的平稳性与叶绿素含量测定的准确性密切相关;叶绿素提取液浓度越低,吸光度越稳定,当提取液浓度低于0.68cm^2·mL^(-1)时,吸光度不再变化。

To evaluate the optimum concentration of chlorophyll extract for determination of chlorophyll content,chlorophyll was extracted from“Jinchang No.1”jujuba leaves using ethanol and acetone-ethanol mixture(1∶1).Chlorophyll extract was diluted to obtain different concentration gradients,and the content was determined using spectrophotometry.Our results showed that the optimum concentration of chlorophyll extract should be less than 0.80 cm 2·mL-1(equal to 14.67 mg·mL-1),which was consistent with the results from a two curve fitting analysis performed in Excel.The stability of absorbance(A)ratio was directly related to accuracy of chlorophyll content;the lower the concentration of chlorophyll extract,the more stable were the values of A.The values of A did not change when the concentration of chlorophyll extract was lower than 0.681 cm 2·mL-1.