Research and analysis

HFE 7100 replacement research

Published 31 January 2024

3M will stop the manufacture of per- and polyfluoroalkyl substances (PFAS) by the end of 2025. This includes Novec™ 7100, also known as HFE 7100 (an engineered fluid containing a mixture of Methylnonafluorobutyl ether and 1-Methoxynonafluorobutane). The European Chemical Agency (ECHA) are also considering the restriction of PFAS.

These restrictions could be enforced in 2026 at the earliest. They could also result in a ban on the manufacture and use of the substances in Europe. Derogations are proposed for specific applications which allow for an extension to the deadline (by up to 12 years). It is not known if forensics will be covered though. The restriction would affect the availability of these chemicals and similar legislation may also be introduced in the UK.

Since the phase out of chlorofluorocarbons (CFCs), the Fingermark Visualisation Manual (FVM) recommends HFE 7100 as the carrier solvent for amino acid reagents. As these processes are important in fingermark enhancement laboratories (FELs), Dstl are investigating several different options to maintain this capability in consultation with the Home Office, Forensic Capability Network and Forensic Science Regulator.

Indandione is the most effective amino acid technique and so the priority is to develop an alternative formulation for this first. There is also a need for a replacement Ninhydrin formulation, as well as a safe and effective process for use at scenes. We anticipate that lessons learnt from replacing HFE 7100 in the Indandione formulation will enable these other processes to be resolved in succession.

Please contact us if you become aware of alternative solvent replacements or HFE replacement research that may be of interest.

Short-term option: alternative supplier

We are aware of a few potential ‘drop-in’ replacements that are marketed as being the same chemical composition as Novec™ 7100. Once samples of these are obtained, we will conduct confirmatory testing and release a report to UK FELs. Although this provides a temporary alternative, ‘drop-in’ replacements are still PFAS and so would be affected if the restrictions from ECHA are introduced.

Longer term options: non-PFAS alternatives

Solvent-less application methods will provide a more sustainable process in the future. Dstl will monitor research in this area - such as the PhD study funded by the Knowledge Transfer Partnership between West Technology and De Montfort University^{[footnote 1]}. As solvent-less techniques are still in their infancy, Dstl’s in-house research currently focusses on solvent-based alternatives; flammable and non-flammable solvents.

Figure 1: chart showing options currently being explored by Dstl

Option A: flammable solvents

Flammable alternatives (such as petroleum ether) are already in use internationally as a carrier solvent for Ninhydrin and Indandione. They are effective in fingermark development, but the potential health and safety hazards to staff, laboratories and crime scenes (for example, the risk of fire and the creation of a potentially explosive atmosphere) must be seriously considered and investigated. Incidents of fires have been reported in fingerprint laboratories using these solvents where the controls were insufficient.

We are commissioning a thorough assessment of the process to explore safe ways of working and to ensure compliance with the Dangerous Substances and Explosive Atmospheres Regulations (DSEAR) 2002. For example, we may need to adapt current methodology or equipment, which could have implications to FELs implementing the process. This may be unavoidable to retain the capability of amino acid chemical treatment but we will inform the user community when we have more information.

Option B: non-flammable solvents

In the current market, there is only 1 non-flammable, non-PFAS solvent that has been identified that could replace HFE 7100; Amolea AS-300 (also known as Maxion 100). De Montfort University1 have carried out some initial testing. They found that although it successfully developed fingerprints, it caused substantial ink running. Dstl plan to carry out further research to determine the effectiveness of this solvent and to see if the ink running could be reduced. We also anticipate that other products will become available as industry responds to the potential PFAS restriction, and we will continue to monitor the market.

Summary

Alternative suppliers to 3M may offer chemically equivalent products to Novec™ 7100, but these will only be short-term alternatives if PFAS are restricted. Dstl are researching non-PFAS alternative solvents, which include both flammable and non-flammable options, in order to maintain the use of amino acid chemical treatment processes in FELs.

1. Able, J., Armitage, R., Deacon P., Farrugia, K.J., Further research into alternative carrier solvents for the detection of latent fingermarks, submitted October 2023. ↩