Replacing Synperonic® N in the Physical Developer fingermark visualisation process: Reformulation.

The Physical Developer solution currently recommended for use in the United Kingdom for fingermark visualisation uses two surfactants: n-dodecylamine acetate (nDDAA) and Synperonic® N. Synperonic® N is covered by the EU directive 82/242/EEC, which sought to phase out chemicals with degradation products more harmful than their precursor. This study explores the replacement of Synperonic® N with alternative detergents and examines their ability to produce clear, stable solutions that are effective at developing fingermarks. The critical properties of the detergents were investigated, such as the critical micelle concentration and the hydrophilic-lipophilic balance, and planted mark comparisons were performed on promising formulations. Tween® 20 was deemed unsuitable due to the production of cloudy solutions and the requirement to age the formulation to improve effectiveness. Brij® C10 produced clear formulations; however, these were too stable causing unacceptably long exhibit processing times, and an additional preparation stage was necessary. Brij® L23, Brij® S10, Igepal® CO-630, Polyoxyethylene (10) tridecyl ether and Tergitol™ 15-S-9 also proved to be unsuccessful alternatives. Decaethylene glycol monododecyl ether (DGME) was found to be a suitable alternative to Synperonic® N and depletion series experiments suggested that a range of DGME and nDDAA detergent quantities were effective at developing marks. The processing time using DGME was similar to Synperonic® N and the most favourable ratio of reagents is proposed in this paper as a reformulated Physical Developer solution.

Replacing Synperonic® N in the physical developer fingermark visualisation process: Pseudo-operational trial and parameter studies.

A reformulated physical developer (PD) solution has been devised to replace the use of Synperonic® N for environmental reasons. The performance of the replacement solution has proved promising in laboratory trials using planted fingermarks [1] however; this may not always represent how a reagent works on real world samples. This paper therefore explores the effectiveness of the decaethylene glycol monododecyl ether (DGME)-based PD formulation through a pseudo-operational trial. A range of naturally handled, porous substrates were processed, which totalled over 600 samples that had been previously treated with amino acid reagents (1,2-indandione (IND) or 1,8-diazafluoren-9-one (DFO) and ninhydrin). The trial was representative of the operational use of PD at the end of a processing sequence for porous exhibits. The results from the trial establish that DGME is an effective replacement detergent for Synperonic® N in PD solutions and demonstrated the added benefit of using PD as a sequential treatment. Planted mark studies to assess the parameters of the DGME-based PD formulation are also included in this paper. These studies explored the preparation, processing and storage temperature required for the solution as well as the shelf life. The effectiveness of DGME-based PD on items that have been previously wetted was also investigated. These studies show the formulation is suitable for use in an operational laboratory and is therefore an effective replacement formulation for the Synperonic® N-based PD.