Multivariate analysis of energy dispersive X-ray diffraction data for the detection of illicit drugs in border control

Abstract

A system using energy dispersive X-ray diffraction has been tested to detect the presence of illicit drugs concealed within parcels typical of those which are imported into the UK via postal and courier services. The system was used to record diffraction data from calibration samples of diamorphine (heroin) and common cutting agents and a partial least squares regression model was established between diamorphine concentration and diffraction spectra. Parcels containing various crystalline and amorphous materials, including diamorphine, were then scanned to obtain multiple localised diffraction spectra and to form a hyperspectral image. The calibration model was used for the prediction of diamorphine concentration throughout the volume of parcels and enabled the presence and location of diamorphine to be determined from the visual inspection of concentration maps. This research demonstrates for the first time the potential of an EDXRD system to generate continuous hyperspectral images of real parcels from volume scanning in security applications and introduces the opportunity to explore hyperspectral image analysis in chemical and material identification. However, more work must be done to make the system ready for implementation in border control operations by bringing down the procedure time to operational requirements and by proving the system's portability.

Portable testing techniques for the analysis of drug materials

“…It is used in border control for both illicit drug and explosive screening, and the advancements in the portability of instruments are ongoing (Drakos, 2015). Recently, an investigation into the use of a portable energy‐dispersive XRD to reduce the time to screen parcels has been of interest to ideally bring the parcel screening time at UK borders down from the current 30 min (Drakos et al, 2017). This method can determine the concentration of diamorphine in a range of parcels containing other materials such as sodium bicarbonate and textiles, which is advantageous for border control.…”

X-ray fan beam coded aperture transmission and diffraction imaging for fast material analysis

“…On the other hand, synchrotron-based XRD imaging 15 requires highly advanced and specialized facilities that are not accessible to all scientists or clinicians. XRD imaging, in shorter scan times and smaller laboratory and clinical environments, remains highly desirable and has been the subject of recent exploration 16 , 17 .…”

Determination of ingredients in packaged pharmaceutical tablets by energy dispersive X‐ray diffraction and maximum likelihood principal component analysis multivariate curve resolution‐alternating least squares with correlation constraint

“…Energy dispersive X‐ray diffraction (EDXRD) can meet this requirement and measures the coherent scattering fields, which characterise the samples comprising crystalline and polycrystalline materials. Polycrystalline materials are of particular interest in screening contexts, where investigations have shown the potential of EDXRD in identifying the composition of solid‐dosage pharmaceutical formulations, powder‐form illicit drugs and plastic explosive materials 1–4 . Furthermore, the technology has shown potential in diagnostic medicine to discriminate between healthy and cancerous tissue in breast cancer screening 5 …”

“…Polycrystalline materials are of particular interest in screening contexts, where investigations have shown the potential of EDXRD in identifying the composition of soliddosage pharmaceutical formulations, powder-form illicit drugs and plastic explosive materials. [1][2][3][4] Furthermore, the technology has shown potential in diagnostic medicine to discriminate between healthy and cancerous tissue in breast cancer screening. 5 Traditional application of X-ray diffraction in a laboratory setting, either with a synchrotron radiation source or a conventional mono-energetic angular dispersive X-ray diffraction (ADXRD) system, enables high-resolution sample profiles to be recorded.…”

“…To overcome the collinearity and overlap within profiles, well-established multivariate calibration methods using orthogonal latent variables, such as principal components regression (PCR) and partial least squares regression (PLSR), have been used in EDXRD studies to quantify target compounds within mixtures. 1,3,8 A disadvantage of this approach is that the latent variables resolved cannot be easily interpreted since they do not represent a pure instrumental response of a single compound.…”