Schneider Ralph Carsten, Kovar Karl-Artur
Department of Pharmaceutical Analysis, Pharmaceutical Institute, University of Tübingen, Auf der Morgenstelle 8, 72076 Tübingen, Germany.
Forensic Sci Int. 2003 Jul 8;134(2-3):187-95. doi: 10.1016/s0379-0738(03)00125-7.
Calibration models for the quantitation of commonly used ecstasy substances have been developed using near infrared spectroscopy (NIR) in diffuse reflectance and in transmission mode by applying seized ecstasy tablets for model building and validation. The samples contained amphetamine, N-methyl-3,4-methylenedioxy-amphetamine (MDMA) and N-ethyl-3,4-methylenedioxy-amphetamine (MDE) in different concentrations. All tablets were analyzed using high performance liquid chromatography (HPLC) with diode array detection as reference method. We evaluated the performance of each NIR measurement method with regard to its ability to predict the content of each tablet with a low root mean square error of prediction (RMSEP). Best calibration models could be generated by using NIR measurement in transmittance mode with wavelength selection and 1/x-transformation of the raw data. The models build in reflectance mode showed higher RMSEPs using as data pretreatment, wavelength selection, 1/x-transformation and a second order Savitzky-Golay derivative with five point smoothing was applied to obtain the best models. To estimate the influence of inhomogeneities in the illegal tablets, a calibration of the destroyed, i.e. triturated samples was build and compared to the corresponding data of the whole tablets. The calibrations using these homogenized tablets showed lower RMSEPs. We can conclude that NIR analysis of ecstasy tablets in transmission mode is more suitable than measurement in diffuse reflectance to obtain quantification models for their active ingredients with regard to low errors of prediction. Inhomogeneities in the samples are equalized when measuring the tablets as powdered samples.
通过使用缉获的摇头丸片剂进行模型构建和验证，已开发出用于定量常用摇头丸物质的校准模型，采用近红外光谱（NIR）在漫反射和透射模式下进行。样品包含不同浓度的苯丙胺、N-甲基-3,4-亚甲基二氧基苯丙胺（MDMA）和N-乙基-3,4-亚甲基二氧基苯丙胺（MDE）。所有片剂均使用配备二极管阵列检测的高效液相色谱（HPLC）作为参考方法进行分析。我们评估了每种近红外测量方法在以低预测均方根误差（RMSEP）预测每片片剂含量方面的性能。通过在透射模式下使用近红外测量并结合波长选择和原始数据的1/x变换，可以生成最佳校准模型。在反射模式下构建的模型在使用数据预处理时显示出更高的RMSEP，应用波长选择、1/x变换和具有五点平滑的二阶Savitzky-Golay导数来获得最佳模型。为了估计非法片剂中不均匀性的影响，构建了对被破坏即研磨后的样品的校准，并将其与整片剂的相应数据进行比较。使用这些均质化片剂的校准显示出较低的RMSEP。我们可以得出结论，就预测误差较低而言，在透射模式下对摇头丸片剂进行近红外分析比在漫反射模式下测量更适合获得其活性成分的定量模型。当将片剂作为粉末状样品进行测量时，样品中的不均匀性会得到均衡。
