采用傅里叶变换红外测试氧化淀粉中的羧基含量， 以国标法测得的羧基含量为纵坐标， 谱图中羰基吸光度与C—H键吸光度比值为横坐标绘制得到标准曲线。 对未知氧化淀粉产物进行红外测试， 得到吸光度比值通过标准曲线方程， 计算其羧基含量， 得到的羧基含量与采用国标法测试的羧基含量进行对比， 误差在2%～4%之间。 为了提高实验的准确度， 选取标样绘制标准曲线时， 必须保证待测氧化淀粉的羧基含量在标准曲线计算的极限值范围之内， 且偏离标准曲线的极限值。 与国标法测试羧基含量相比， 采用红外测试， 方法简单易操作， 效率高， 准确度好。 因此采用红外光谱测试方法对氧化淀粉的羧基含量的预测具有一定重要意义。

In the present study, the carboxyl content of oxidized starch was determined by FTIR spectroscopy. Standard curve was drawn in which the ordinate was carboxyl content determined by national standard method with the ratio of carbonyl absorbance to the key of C—H absorbance in FTIR spectroscopy as the abscissa. The ratio of absorbance of unknown oxidized starch tested by FTIR spectroscopy was obtained, The carboxyl content was calculated by standard curve, and then compared with the carboxyl content determined by national standard method, and the deviation is between 2% and 4%. In order to improve the accuracy of the experiment，standard sample was selected to draw standard curve to better ensure that the carboxyl content of the unknown oxidized starch is in the range of standard curve calculation limit, and deviates from the limit of standard curve. Compared with the carboxyl content determined by national standard method, testing with FTIR spectroscopy is simple, easy to operate, and of high efficiency and better accuracy. So, it is significant to forecast the carboxyl content of oxidized starch by FTIR spectroscopy.