Because of the low active component

由于研究药物中活性成分的浓度较低，因此所测光谱的强度较弱。这意味着获得的光谱的特征是信噪比（S / N）值非常低，约为30。在双氯芬酸钠溶液中，主成分分析（PCA）表明，在这样一个复杂的系统中前五个主要成分只能解释大约85％的光谱变化。接下来的与噪声和基线波动有关的主要成分缓慢下降。频谱平滑后，前五个主要成分占研究系统频谱变化的近94％，但是平滑对精细校准模型参数的影响可忽略不计。<br><br>最初，选择单离方法在1581和1604 cm-1处分离出的双氯芬酸峰进行分析。有必要假设存在于研究系统中的其余物质在该光谱区域中不会强烈干扰。使用一点基线校正计算带强度和带面积。如人们所料，单变量校准模型的质量较低。获得的校准曲线的测定系数R2等于0.852或0.796（表1）。对于测试数据集确定的预测的相对标准误差，对于基于带面积和带强度的模型，分别为11.5和13.7％。

Because of the low active component concentration in the studied pharmaceuticals, the intensities of the measured spectra were weak. It means that the spectra obtained were characterised by a rather low signal-to-noise (S/N) value of the order of 30. In the case of diclofenac sodium solutions the principal component analysis (PCA) showed that in such a complex system only about 85% of the spectral variation could be accounted for by the first five principal components. The next principal components connected with the noise and fluctuations of the baseline decreased slowly. After smoothing of the spectra, the first five principal components accounted for nearly 94% of the spectral variation in the studied system, however smoothing had negligible influence on the parameters of the elaborated calibration models.<br><br>At the beginning, isolated diclofenac peaks at 1581 and 1604 cm−1 were chosen to perform analysis in a classical way, using a univariate approach. It was necessary to assume that the remaining substances, present in the studied systems, did not interfere strongly in this spectral region. Band intensities and band areas were calculated applying one-point baseline correction. As one could expect, univariate calibration models were of low quality. The determination coefficient, R2, for obtained calibration curves equalled 0.852 or 0.796 (Table 1). The relative standard error of prediction determined for the testing data set amounted to 11.5 and 13.7%, for the model based on band area and band intensity, respectively.

由于所研究的药物中的活性成分浓度较低，因此测得的光谱强度较弱。这意味着获得的光谱具有相当低的信噪比（S/N）值（30阶）。对于双氯芬酸钠溶液，主成分分析（PCA）表明，在这样一个复杂的体系中，前五个主成分只能解释大约85%的光谱变化。下一个与基线噪声和波动相关的主成分下降缓慢。对光谱进行平滑处理后，前五个主成分占系统光谱变化的94%，而平滑处理对校正模型参数的影响可以忽略不计。<br>开始时，选择1581和1604cm-1处的分离双氯芬酸峰，采用单变量方法进行经典分析。有必要假设，研究系统中存在的剩余物质不会强烈干扰该光谱区域。应用一点基线校正计算带强度和带面积。正如人们所料，单变量校准模型的质量很低。所得校准曲线的测定系数R2等于0.852或0.796（表1）。基于能带面积和能带强度的模型对测试数据集的预测相对标准误差分别为11.5%和13.7%。<br>