Department of Drugs and Toxicology, National Institute of Criminalistics and Criminology, Brussels, Belgium; AXES Research Group, Chemistry Department, University of Antwerp, Antwerp, Belgium.
Department of Drugs and Toxicology, National Institute of Criminalistics and Criminology, Brussels, Belgium.
Talanta. 2020 Mar 1;209:120481. doi: 10.1016/j.talanta.2019.120481. Epub 2019 Oct 21.
A portable Fourier Transform Mid-InfraRed (FT-MIR) spectrometer using Attenuated Total Reflectance (ATR) sampling is used for daily routine screening of seized powders. Earlier, ATR-FT-MIR combined with Support Vector Machines (SVM) algorithms resulted in a significant improvement of the screening method to a reliable and straightforward classification and quantification tool for both cocaine and levamisole. However, can this tool be transferred to new (hand-held) devices, without loss of the extensive data set? The objective of this study was to perform a calibration transfer between a newly purchased bench top (BT) spectrometer and a portable (P) spectrometer with existing calibration models. Both instruments are from the same brand and have identical characteristics and acquisition parameters (FT instrument, resolution of 4 cm and wavenumber range 4000 to 500 cm). The original SVM classification model (n = 515) and SVM quantification model (n = 378) were considered for the transfer trial. Three calibration transfer strategies were assessed: 1) adjustment of slope and bias; 2) correction of spectra from the new instrument BT to P using Piecewise Direct Standardization (PDS) and 3) building a new mixed instrument model with spectra of both instruments. For each approach, additional cocaine powders were measured (n = 682) and the results were compared with GC-MS and GC-FID. The development of a mixed instrument model was the most successful in terms of performance. The future strategy of a mixed model allows applying the models, developed in the laboratory, to portable instruments that are used on-site, and vice versa. The approach offers opportunities to exchange data within a network of forensic laboratories using other FT-MIR spectrometers.
一种使用衰减全反射（ATR）采样的便携式傅里叶变换中红外（FT-MIR）光谱仪，用于日常扣押粉末的例行筛查。此前，ATR-FT-MIR 与支持向量机（SVM）算法相结合，显著提高了筛选方法的可靠性和简便性，成为可卡因和左旋咪唑的可靠分类和定量工具。然而，这种工具能否在不损失广泛数据集的情况下转移到新的（手持式）设备上？本研究的目的是在新购买的台式（BT）光谱仪和便携式（P）光谱仪之间进行校准转移，使用现有的校准模型。这两种仪器均来自同一品牌，具有相同的特性和采集参数（FT 仪器，分辨率为 4 cm，波数范围为 4000 至 500 cm）。原始 SVM 分类模型（n=515）和 SVM 定量模型（n=378）被认为是转移试验的对象。评估了三种校准转移策略：1）调整斜率和偏差；2）使用分段直接标准化（PDS）校正新仪器 BT 的光谱；3）使用两个仪器的光谱构建新的混合仪器模型。对于每种方法，都测量了更多的可卡因粉末（n=682），并将结果与 GC-MS 和 GC-FID 进行了比较。混合仪器模型的开发在性能方面最为成功。混合模型的未来策略允许将在实验室开发的模型应用于现场使用的便携式仪器，反之亦然。该方法为使用其他 FT-MIR 光谱仪在法医实验室网络中交换数据提供了机会。
