Forensic classification of counterfeit banknote paper by X-ray fluorescence and multivariate statistical methods

Area of Science:

• Forensic Science
• Analytical Chemistry
• Materials Science

Background:

• Banknote counterfeiting poses significant economic threats.
• Analyzing materials like paper, ink, and toners can link counterfeit cases.
• Identifying common raw materials used by counterfeiters is crucial for law enforcement.

Purpose of the Study:

• To investigate the utility of elemental composition analysis for classifying counterfeit banknote papers.
• To determine if X-ray fluorescence (XRF) can differentiate and group counterfeit banknote samples.
• To assess the potential of statistical methods in linking counterfeit cases based on paper analysis.

Main Methods:

• Twenty-one counterfeit banknote paper samples from 13 cases were analyzed.
• Wavelength dispersive X-ray fluorescence (XRF) was employed for elemental composition measurement.
• Multivariate statistical methods, including cluster analysis and principal component analysis, were applied to the data.

Main Results:

• Semi-quantitative elemental composition data for 10 elements were obtained.
• The analyzed paper samples were primarily classified into 3 distinct groups.
• Nine separate criminal cases were successfully linked based on paper sample similarities.

Conclusions:

• Elemental composition analysis of banknote paper using XRF is a valuable forensic tool.
• XRF provides a reliable method for comparing and classifying papers used in different counterfeiting operations.
• This technique aids in connecting counterfeit cases and identifying common sources of illicit materials.