Oral Presentation Royal Australian Chemical Institute National Congress 2026

Eliminating PFAS solvents from fingermark development processes (136440)

Jodie L Harrington 1 , Kristen T Clarke 1 2 , Matthew N Krosch 2 , Sina S Jamali 1 3 , William J Gee 1
  1. School of Environment and Science, Griffith University, Brisbane, QLD, Australia
  2. Quality Management Section, Forensic Services Group, Queensland Police Service, Brisbane, QLD, Australia
  3. Queensland Quantum and Advanced Technologies Research Institute, Griffith University, Brisbane, QLD, Australia

The ability to visualise fingermarks on a variety of surfaces is an essential tool in forensic science and law enforcement. Porous substrates, such as paper, absorb the water-soluble (eccrine) components of fingerprints, thereby requiring an amino acid-targeting reagent for development. Operationally, 1,2-indanedione (IND) and zinc chloride are employed in a carrier solvent of HFE-7100, producing coloured, fluorescent fingermarks. HFE-7100 was introduced into fingermark development as a replacement for chlorofluorocarbons (CFCs); however, the manufacturer of HFE-7100, 3M, has now discontinued production of all per- and polyfluoroalkyl substances (PFAS), making it nearly impossible to source and necessitating the urgent identification of a suitable replacement that also addresses the recurring issue of solvent phase-outs.1

 

Many alternatives have been suggested to replace HFE-7100, but they are either costly, flammable, or have other practical drawbacks, such as low boiling points in warm climates, making them unsuitable as long-term replacements. The ideal low-cost, safest and greenest carrier solvent replacement is water. However, indanedione lacks solubility in water and can cause amino acids to dissolve, subsequently blurring or even washing away the fingermark.

 

A xanthan gum-based hydrogel delivery system has been shown to reveal fingermarks left on paper.2 The drawback of this approach is occasional blurring of ridge detail and streaking defects during manual application of the gel, which were linked to inconsistencies in the gel structure and in the application pressure. In this work, the IND hydrogel application process has been automated using an automatic film applicator. The application of thinner gels with more even pressure reduced streaking in the treated fingermarks and improved clarity of ridge detail. Other features explored in this work include a heated vacuum bed that secures the substrate and rapidly dries the applied gels, further mitigating blurring. Overall, this work demonstrates that hydrogels provide a sustainable, PFAS-free alternative for fingermark development.

  1. 1. 3M, https://news.3m.com/2022-12-20-3M-to-Exit-PFAS-Manufacturing-by-the-End-of-2025, (accessed January 2026)
  2. 2. K. T. Clarke, S. L. Hopkins, M. N. Krosch, S. L. Cresswell and W. J. Gee, Forensic Chemistry, 2025, 43, 100650.