The Role of XRD in Modern Forensic Materials

The increasing availability, consumption and ongoing development of illegal drugs has seen their analysis become a key element of contemporary forensic science. In order to trace drugs’ source, their type, form and composition must be accurately determined.

XRD (X-ray diffraction) analyses are a critical step in the analytical workflow of many forensic labs working with a range of powder and bulk samples, for example, drug-related samples and various other samples, including soils or textiles.

XRD analyses are able to verify findings from complementary analytical techniques such as mass spectrometry, offering key additional information about crystalline structures, which is useful in ascertaining phase quantities from complex mixtures.

Scientists in forensics laboratories working to analyze drug-related samples using XRD must consider three key questions:

  1. Is it possible to confirm results gained using related techniques; for example, is the preliminary test result that showed the presence of heroin valid?
  2. What chemical form of drug is present; for example, does the result show the base or hydrochloride hydrate form of heroin?
  3. Is it possible to both identify and quantify additional phase, and also the main drug component? This question is especially important when tracing and clustering drug samples.

This article aims to answer all three of these questions using a range of test samples.

ARL EQUINOX 100 diffraction system.

Figure 1. ARL EQUINOX 100 diffraction system. Image Credit: Thermo Fisher Scientific - Elemental Analyzers and Phase Analyzers

The ARL™ EQUINOX Series from Thermo Scientific™ is part of a portfolio of XRD instruments that ranges from simple, user-friendly bench-top systems designed for routine analysis to sophisticated floor-standing, research-grade systems.

The Thermo Scientific™ ARL™ EQUINOX 100 makes use of a custom-designed 50 W (Cu or Mo) or 15 W (Co) high-brilliance micro-focus tube. This tube utilizes mirror optics, removing any need for an external water chiller.

The unit can also be transported into the field or between laboratories without the use of specialized infrastructure.

The ARL™ EQUINOX 100 (Figure 1) offers rapid data collection when compared with other diffractometers. This is due to its unique curved position sensitive detector (CPS), which is able to provide real-time measurement of all diffraction peaks simultaneously.

Experimental

The scientific police provided the powdered drug samples, who also helped to evaluate these samples. Measurement was performed in reflection using an ARL™ EQUINOX 100 with Cu Kα radiation.

Results

Different chemical forms exist for many drug-related compounds. These include salts, hydrochlorides, stereoisomers and more.

Heroine Hydrochloride Monohydrate (10 min measurement time)

Figure 2. Heroine Hydrochloride Monohydrate (10 min measurement time). Image Credit: Thermo Fisher Scientific - Elemental Analyzers and Phase Analyzers

Each of these forms has the potential to prompt different physical effects, meaning that properly identifying these via sample tracing is vital. Figure 2 explicitly displays heroin in its hydrochloride monohydrate form in comparison with its base form.

Comparisons such as these allow users to evaluate related samples and trace their origin. There were no diluents detectable in this sample, meaning that it was most likely not designated for end customers’ distribution.

As well as the diluents present, the content of active ingredients in drugs also varies. Because of this, a critical element in the drug analysis process is the identification of phases and their respective quantification.

Cocaine blend Sample 1 (10 min measurement time).

Figure 3. Cocaine blend Sample 1 (10 min measurement time). Image Credit: Thermo Fisher Scientific - Elemental Analyzers and Phase Analyzers

Cocaine blend Sample 2 (10 min measurement time.

Figure 4. Cocaine blend Sample 2 (10 min measurement time. Image Credit: Thermo Fisher Scientific - Elemental Analyzers and Phase Analyzers

Figures 3 and 4 display two different types of cocaine hydrochloride samples. Each sample is primarily diluted with α-lactose, and each contains varying amounts of caffeine and other drug-related compounds. Sample 1 has a cocaine content of ~35 wgt%, while Sample 2 has a cocaine content of >90 wgt%.

Conclusion

The ARL™ EQUINOX 100 XRD is able to measure most drug-related samples within 10 minutes. A combination of the MDI JADE 2010 and the ICDD pdf 4 Organics database facilitates qualitative and quantitative phase analysis (WPF Rietveld refinement) of the samples.

These results definitively illustrate the type, form and composition of the samples, therefore allowing for the effective tracing and identification of these drugs.

Acknowledgments

Produced from materials originally authored by Dr. Simon Welzmiller, Application Specialist, and Dr. Henry Pilliere, Research Manager at Thermo Fisher Scientific.

This information has been sourced, reviewed and adapted from materials provided by Thermo Fisher Scientific - Elemental Analyzers and Phase Analyzers.

For more information on this source, please visit Thermo Fisher Scientific - Elemental Analyzers and Phase Analyzers.

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