Non-Destructive Identification of Drugs in Plastic Packaging Using Attenuated Total Reflection Terahertz Time Domain Spectroscopy

Abstract

In this study, we demonstrate that drugs in plastic packaging can be identified without being opened using attenuated total reflection terahertz time domain spectroscopy. In this system, the terahertz wave undergoes total internal reflection at the interface between prism and sample, producing an evanescent wave at the interface. The penetration depth of the evanescent waves is larger than the thickness of typical plastic packaging in the sub-terahertz frequency region; therefore, it becomes possible to detect the sample without opening the package. Here, we show that some saccharides samples such as lactose in plastic packaging can be identified using its spectral fingerprint by placing the packaged lactose on the prism. This method has the potential to be used in the non-destructive testing and analysis of a wide variety of samples, such as medicine sachets, to reduce medication dispensing errors in pharmacies.

Keywords

• terahertz
• spectroscopy
• non-destructive testing
• attenuated total reflection
• refractive index
• absorption coefficient