Technologies for counterfeit detection
XRPD can be used to identify crystalline substances, including all related polymorphs. This group includes solid APIs and excipients. Modern transmission optics have made direct analysis through blister packaging possible as well. Using a database for comparison, the software can automatically and easily identify fraudulent drugs. The advantage of this technique is that the drug can be confirmed without being removed from the blister. It can then be simply repackaged or sold as seen fit.
Furthermore, with XRPD, multiple drug forms and concentrations can be determined. This feature can be beneficial in identifying materials that are expired original-real products. In such cases, it is likely that degraded substances would be present, which can easily be detected by XRPD fingerprinting.
Traditionally, EDXRF spectrometry has been used for qualification and quantification of elements across the periodic table. Solid-dosage products have a well-defined shape and are primarily made of excipient materials, most of which are natural materials with characteristic elemental signatures. Therefore, a simple scan method that takes only a few minutes can be used to produce spectra, which then can be compared with a library of scans of authentic materials. This entire process can be automated, and using multivariate or spectral regression algorithms, used to repeatedly identify counterfeit materials.
Moreover, EDXRF scans can be used for elemental quantification to identify health risk factors such as toxic heavy metals (e.g., arsenic (As), lead (Pb), cadmium (Cd) or mercury (Hg)). Such information is not only useful for authorities to determine additional health-risk factors, but can also be invaluable in criminal-source material tracking and distribution investigations.
Comparing XRPD and EDXRF with handhelds
Although handhelds have the advantage of portability, which is particularly evident in field operations where agents require a lightweight tool for a quick screen, this often comes at a cost, for example, reduced automation, limited software fingerprinting algorithms, and difficult database management. Currently, only handheld vibrational (IR and Raman) and XRF instruments are established. Portable XRD instruments exist but generally have poor resolution and are prone to environmental conditions and variability than dedicated laboratory or benchtop systems. All portable XRD instruments have traditional reflection geometrical optical designs, which means that whole tablets cannot be measured (i.e., the tablets must be destructively powdered). The result can lead to a great loss of additional intelligence and the use of an article for legal proceedings.
Generally, it is good practice to compare scans/diffraction patterns acquired under similar conditions. Most pharmaceutical laboratories own XRPD systems and some are purchasing XRF for applications to meet the new US Pharmacopeia General Chapter <232> Elemental Impurities–Limits. These technologies can also be used going forward in counterfeit analysis.