Editorial Feature

Analyzing Surface Yellowing of Drug Tablets With ToF Secondary Ion Mass Spectrometry

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Contemporary techniques of surface chemical characterization have a vital role to play in the research and advancement of pharmaceutical products.

The two most important surface analysis techniques are time-of-flight secondary ion mass spectrometry (ToF-SIMS) and X-ray photoelectron spectroscopy (XPS). Their features are listed below:

X-Ray Photoelectron Spectroscopy (XPS)

  • Quantitative analysis
  • Elemental and chemical state information.

Time of Flight Secondary Ion Mass Spectroscopy (ToF-SIMS)

  • Imaging with a high spatial resolution (< 200 nm)
  • Comprehensive and highly specific chemical information (chemical groups, elements, molecules, and polymer structures)
  • Extremely sensitive (trace detection limits)

Case Study

Surface Yellowing of a Drug Tablet upon Light Exposure

ToF-SIMS was used to examine the issue of yellow discoloration of white drug tablets when they are exposed to light.

The data demonstrated that selective degradation of the drug molecule had occurred where an acetic acid group was changed to an aldehyde group (mass difference = 30). This led to the development of a new molecule (Mdeg) with a mass of 30 less than the pristine molecule (Mdrug), where M is equal to molecular mass.

Coupling of this aldehyde group with an aromatic ring caused a shift in the light absorption from the ultra-violet region of the electromagnetic spectrum into, at least partially, the blue region of the visible spectrum, leading to the yellow discoloration.

Pharmaceutical White Paper-Surface Analysis Exposes Counterfeit Drugs

Since counterfeit drugs are becoming more and more available (the US-based Center for Medicines in the Public Interest expects that counterfeit drug sales will be worth an estimated US$75 billion worldwide in 2010), the technology that is used to produce these counterfeit medicines is becoming increasingly advanced.

CERAM Surface and Materials Analysis, in collaboration with GlaxoSmithKline, has created a technique for identifying fake tablets, in comparison with genuine drugs, by using methods like ToF-SIMS and XPS.

With reference to standard techniques of analyzing the composition, this technique focuses on process and the manufacturing method of the drugs, the outcome being that earlier undetectable chemical copies of pharmaceuticals can be detected.

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