乙酰溴法测定棉籽壳中木质素的含量

摘要

A new method to determine the amount of lignin in cottonseed coat was established with ultraviolet spectrophotometry,which is based on the strong absorption characteristic of the acetylate derivatives of lignin at 280 nm.The influence of acetyl bromide volume fraction,reaction temperature and time,and perchloric acid mass concentration on lignin acetylation reaction was investigated.And the optimized process conditions were obtained as follows:acetyl bromide volume fraction 30％,reaction temperature 70 ℃,reaction time 60 min,and perchloric acid mass concentration 0.69 mol/L.Compared with Klasson method,the acetyl bromide test method has such advantages as simpliness,rapidness,good reproducibility and precision.%利用木质素乙酰化衍生物在280 nm处具有强烈吸收的特征,建立了一种用紫外分光光度法测定棉籽壳中木质素含量的新方法.研究了木质素乙酰化反应过程中乙酰溴体积分数、反应温度、时间和高氯酸质量浓度的影响规律,得到的优化反应条件为:乙酰溴体积分数30％、反应温度70℃、时间60 min、高氯酸质量浓度0.69 mol/L.在此条件下,乙酰溴法测得的棉籽壳木质素含量为19.59％.与Klasson法相比,该测量方法具有简单迅速,重演性和精密度好的优点.