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ELSEVIER Forensic Science International 284 (2018) 53-64 Contents lists available at ScienceDirect Forensic Science International journal homepage: www.elsevier.com/locate/forsci int An alternative carrier solvent for fingermark enhancement reagents Izabela Olszowskaa, Paul Deaconb, Maurice Lindsay`, Adam LeSniewskia, Joanna Niedziolka-Jonssona, Kevin Farrugia" a Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224, Warsaw, Poland b e/o School of Science, Engineering & Technology, Division of Science, Abertay University, Bell Street, Dundee, DDI 1HG, UK `School of Science, Engineering & Technology, Division of Science, Abertay University, Bell Street, Dundee, DDI IHG, UK (g ) Check for ARTICLE INFO Article history: Received 22 September 2017 Received in revised form 27 November 2017 Accepted 5 December 2017 Available online 11 December 2017 Keywords: Ninhydrin DF0 1,2-indanedione HFE7100 Solstice PF Pseudo-operational trial ABSTRACT Solstice Performance Fluid (PF), trans-1-chloro-3,3,3-trifluoropropene, is presented as an alternative to HFE7100, methoxy-nonafluorobutane, as a carrier solvent in a number of chemical formulations used for the visualisation of latent fingermarks. The supply of HFE7100 may be at risk due to a recent European Union regulation to control global warming. Laboratory trials using split depletions and a pseudooperational trial of 1000 porous samples have shown that Solstice PF is a viable alternative to HFE7100 for the chemical formulations of ninhydrin and 1,2-indanedione. Other preliminary trials have also indicated that Solstice PF can be used as a carrier solvent for the zinc toning of marks found using ninhydrin as well as the a-naphtholflavone fixative solution for iodine developed marks. Results from the pseudo-operational trial demonstrate that the number of marks detected by ninhydrin and 1,2indanedione formulations for each carrier solvent is comparable. When compared to HFE7100, advantages of Solstice PF include a very low global warming potential and atmospheric lifetime in addition to a higher wetting index and lower costs. This study also provides a validation study that supports the potential replacement of DFO with 1,2-indanedione. 2017 Elsevier B.V. All rights reserved. 1. Introduction Due to the global warming effect contributed by fluorinated greenhouse gases, the European Parliament is considering a ban on some of the hydrofluorinated solvents listed in Annex II of Regulation (EU) No 517/2014 of 16 April 2014 [1]. Fluorinated gases listed in Annex I of the regulation will see a reduction year on year until 2030 whereas those listed in Annex II are currently only subject to reporting quantities placed on the market to the EU commission. Therefore, an alternative and effective replacement for HFE as the carrier solvent in a number of chemical formulations used in latent fingermark development needs to be investigated due to the potential withdrawal, partial or otherwise, of HFE products. The reaction of ninhydrin with amino acids and proteins to produce a purple colouration (Ruhemann's complex) has been known for over 100 years. The carrier solvent for amino acid reagent formulations has changed many times since the first reported use of ninhydrin as a fingerprint reagent in 1954. Such * Corresponding author. Tel: E-mail address: @abertay.ac.uk (K. Farrugia). https://doi.org/10.1016/j.forsciint.2017.12.012 0379-0738/ 2017 Elsevier B.V. All rights reserved. changes were applied to improve the safety of the reagent (e.g. non-flammable ninhydrin), the performance of the reagent (addition of acetic acid to ninhydrin formulation) and environmental regulations (replacement of CFC-113). Oden and van Hofsten [2] reported one of the first instances of ninhydrin (acetone-based) for the detection of latent fingermarks on paper. Other studies have investigated the use of petroleum ether, 1,1,2trifluorotrichloroethane (CFC-113) and heptane as carrier solvents for the ninhydrin reaction [3-5]. The UK Home Office Centre for Applied Science and Technology (CAST) does not recommend the use of petroleum ether or heptane due to its flammability. In the UK, CFC-113 was the main solvent carrier from 1974 up to the late 1990s until it was banned under the Montreal Protocols of 1987. CAST embarked on a research project to find an alternative for CFC113 formulations that was non-flammable, non-toxic, volatile and relatively non-polar to minimise the diffusion of ink [6,7]. Ideally, the alternative solvent should also provide equivalent, or superior, performance in the detection of latent fingermarks on porous surfaces. An early study identified Genesolv 2000 as a possible replacement for both ninhydrin and DFO; however, the solvent resulted in ink removal or diffusion [8]. CAST identified hydrochlorofluorocarbons (HCFC), hydrofluorocarbons (HFC) and hydrofluoroethers (HFE) as potential replacements to CFC-113. It may be 54 I. Olszowska et al. / Forensic Science International 284 (2018) 53-64 assumed that the efficiency of the reagent is largely unaffected by the choice of carrier solvent; however, trials by CAST have indicated otherwise. Ninhydrin formulations based on two solvents, 2,3-dihydrodecafluoropentane (HFC-4310mee) and 1methoxynonafluorobutane (HFE7100) outperformed CFC-113 formulations based on laboratory trials which were also confirmed by pseudo-operational trials [7,9]. Similar results were reported by Petruncio [10] whereby HFC-4310mee and HFE7100 provided an increased detection rate and reduced ink diffusion in a comparative study including petroleum ether. Around 2009 [11], in an effort to reduce costs to police forces, CAST investigated an alternative solvent for ninhydrin formulations, Asahiklin AE-3000. Initial price estimates were quoted as 30% cheaper than HFE7100; however, further estimates from the supplier indicated that there will be little, if any, cost saving. A pseudo-operational comparative trial between ninhydrin formulations of HFE7100 and AE-3000 indicated that there was no statistical difference between the effectiveness of these two ninhydrin formulations [11,12]. Research has also investigated analogues of ninhydrin to improve the detection of fingermarks by means of better contrast or fluorescence [13-17]. These have largely been replaced by the use of DFO and 1,2indanedione (1,2-IND) which can be prepared using HFE solvents [18-20]. The UK Home Office Fingermark Visualisation Manual (FVM) classifies ninhydrin and DFO as `category A' processes which are defined as "processes extensively evaluated by the Home Office and considered suitably effective. Standard processes for routine opera- tional use. They must be used in preference to other category processes where possible" [21]. 1,2-IND is currently classified as a category B process that is generally less effective but has not been fully evaluated by the Home Office CAST. Nonetheless, in recent newsletter updates, CAST have indicated that 1,2-IND may replace DFO and provided an updated 1,2-IND formulation that supersedes the FVM formulation [22,23]. This study presents a comparative pseudo-operational trial to assess the possible replacement of HFE7100 as the carrier solvent in the ninhydrin and 1,2-IND formulations. The possible replacement solvent is Solstice1 Performance Fluid (Solstice1 PF), trans1-chloro-3,3,3-trifluoropropene, manufactured by Honeywell Research Chemicals. At the same time, this trial also provides a validation study for the potential replacement of DFO with 1,2IND. 2.2. Pseudo-operational trials The extensive pseudo-operational trial was carried out on a variety of porous surfaces (paper, magazines, junk mail, newspaper and envelopes). The substrates were obtained from family, friends, colleagues and recycling bins. A maximum of 10 items was taken from each person. 1000 samples were included in this study and grouped as 250 papers, 250 envelopes, 250 junk mail/magazines and 250 newspaper pages. In the case of newspapers and magazines, the first and last page were included as well as another random two pages in between. The items were treated in 10 batches of 100 samples (25 of each substrate). Each item was split into five equal sections and labelled A (ninhydrin-HFE7100), B (ninhydrin-Solstice1 PF), C (DFO-HFE7100/71DE), D (1,2-INDHFE7100) and E (1,2-IND-Solstice1 PF) (Fig. 1). Sequential treatment with ninhydrin was carried out on processes C-E. The item labelling and treatment was rotated for each sample to eliminate any bias, so, for example, for item no. 2 the order was B, C, D, E and A. Any marks developed with continuous ridge detail and an area greater than 64 mm2 were included in the count for the number of latent marks detected. 2.3. Formulations The effectiveness of the Solstice1 PF solvent used for both ninhydrin and 1,2-IND processes was compared to the standard HFE7100 solvent. The DFO process was included in the study as a validation study for the possible replacement with 1,2-IND. The formulations for processes A, C and D were prepared according to CAST [21,23]. For the Solstice1 PF processes (B and E), the same formulations as recommended by CAST were used by directly replacing the HFE7100 with Solstice1 PF. To minimize evaporation, shallow troughs with a curved, corrugated bottom surface were used for passing through the items [21]. 2.3.1. Ninhydrin A concentrated solution of ninhydrin was prepared by dissolving ninhydrin (25 g, Sigma Aldrich) in ethanol (225 mL, Fisher), glacial acetic acid (25 mL, Fisher) and ethyl acetate (10 mL, Fisher). A working solution was then prepared by measuring 52 mL of the ninhydrin concentrated solution together with HFE7100 (1 L, 2. Methodology The methodology used in this study is based on recommendations for fingermark research from CAST [24] and the International Fingerprint Research Group [25]. 2.1. Laboratory trials Split depletion trials using 5 donors (4 female and 1 male) were tested on white paper. Donors were asked not to wash their hands for at least half an hour prior to deposition. Each donor made a total of 4 depletion series', each containing 8 marks in the depletion. Each series of depletion was divided into half and enhanced with the appropriate enhancement technique. The following comparisons were carried out: ninhydrin-HFE7100 and ninhydrinSolstice1 PF; 1,2-IND-HFE7100 and 1,2-IND-Solstice1 PF; DFOHFE and 1,2-IND-HFE7100 as well as DFO-HFE and 1,2-INDSolstice1 PF. Results were evaluated by putting the split series' back to the original position and grading the developed fingermarks as recommended by CAST [24]. The use of Solstice1 PF was also assessed and compared to HFE7100 in the formulations of zinc toning as well as iodine fixing. Fig. 1. Scheme of sample division for a substrate in the study. I. Olszowska et al. / Forensic Science International 284 (2018) 53-64 55 3 M Novec) or Solstice1 PF (1 L, Honeywell). The articles under examination were drawn through the working solution in the trough and the excess liquid allowed to drain back before drying completely in a fume hood. The articles were then placed in a humidity oven (Gallenkamp FDC018) at 80 C and 65% humidity for 4 min. Observations of developed marks were checked immediately and over the next 10 days. 2.3.2. DFO A DFO working solution was prepared by dissolving DFO (0.25 g, Sirchie) in methanol (30 mL, Fisher) and glacial acetic acid (20 mL, Fisher) followed by the addition of HFE71DE (275 mL, 3 M Novec) and HFE7100 (725 mL, 3 M Novec). The articles under examination were drawn through the working solution in the trough and the excess liquid allowed to drain back before drying completely in a fume hood. The articles were then placed in a dry oven (Hereaus) at 100 C for 20 min. Fluorescence examination was carried out with a Quaser 2000 equipped with a green excitation source (band-pass filter 473-548 nm at 1% cut-on and cut-off points) and viewed with a long-pass 549 nm filter (1% cuton point). 2.3.3. 1,2-Indanedione A working solution of 1,2-IND was prepared by dissolving 1,2- indanedione (0.25 g, BVDA) in ethyl acetate (45 mL Fisher), methanol (45 mL Fisher), glacial acetic acid (10 mL, Fisher) and zinc chloride stock solution (1 mL) followed by the addition of HFE7100 (1 L, 3 M Novec) or Solstice1 PF (1 L, Honeywell). The chemicals were added in the order described as the solution may become unstable or go cloudy. The zinc chloride stock solution was prepared by dissolving zinc chloride (0.1 g, Sigma) in ethyl acetate (4 mL, Fisher) and acetic acid (1 mL, Fisher). The articles under examination were drawn through the working solution in the trough and the excess liquid allowed to drain back before drying completely in a fume hood. The articles were then placed in a dry oven (Hereaus) at 100 C for 10 min. Fluorescence examination was carried out with a Quaser 2000 equipped with a blue/green excitation source (band-pass filter 468-526 nm at 1% cut-on and cut-off points) and viewed with a long-pass 529 nm filter (1% cuton point). 2.3.4. Ninhydrin enhancement - zinc toning A working solution for zinc toning was prepared by dissolving zinc chloride (1.2 g, Acros) in ethanol (10 mL, Fisher), 2-propanol (2 mL, Fisher) and acetic acid (2 mL, Fisher) followed by the addition of HFE7100 (40 mL, 3 M Novec) or Solstice1 PF (40 mL, Honeywell). The solution was then applied through an Ecospray1 fine mist sprayer (nozzle diameter: 0.70 mm, flow rate: 0.45 mL/s) at a distance of approximately 15-20 cm. After drying, the articles were then placed in a humidity oven (Gallenkamp FDC018) at 80 C and 65% humidity for 4 min. Fluorescence examination was carried out with a Quaser 2000 equipped with a blue/green excitation source (band-pass filter 468-526 nm at 1% cut-on and cut-off points) and viewed with a long-pass 529 nm filter (1% cut-on point). 2.3.5. Iodine Iodine crystals were heated gently to about 50 C in a cabinet loaded with the articles under examination. To prevent fading, developed marks were treated with a fixing solution. An iodine fixing solution was prepared by dissolving a-naphthoflavone (0.1 g, Acros) in acetic acid (5 mL, Fisher) followed by the addition of HFE7100 (30 mL, 3 M Novec) or Solstice1 PF (30 mL, Honeywell). The fixing solution was then applied through an Ecospray1 fine mist sprayer (nozzle diameter: 0.70 mm, flow rate: 0.45 mL/s) at a distance of approximately 15-20 cm. 3. Results and discussion 3.1. Solvent properties The solvent industry moved from CFCs to HCFCs, HFCs and HFEs to limit ozone depletion; however, another problem with greenhouse gases and global warming potential (GWP) ensued. The solvent industry then moved to the production of HFOs and HCFOs which have a much shorter lifetime in the atmosphere as well as a very low GWP. GWP is defined as the "climatic warming potential of a greenhouse gas relative to that of CO2 calculated in terms of the 100-year warming potential of one kilogram of a greenhouse gas relative to one kilogram of CO2 [1]. A suitable alternative solvent to HFE7100 should ideally be nonflammable, non-toxic, volatile, environmentally friendly and relatively non-polar to minimise the diffusion of ink. Solstice1 PF, manufactured by Honeywell, fulfills these criteria and when compared to HFE7100 has a lower toxicity and surface tension as well as a higher wetting index. The high wetting index indicates that the solvent can be absorbed easier by the substrate to reach amino acids ingrained in the pores of the porous substrate. Although a fluorinated solvent itself, Solstice1 PF has a very low GWP rate of 1 and atmospheric lifetime of 26 days compared to a GWP of 320 and an atmospheric lifetime of 4.1 years for HFE7100. Table 1 summarises the solvent properties of Solstice1 PF, HFE7100 and CFC-113. Solstice1 PF has a boiling point of 19 C but a high enthalpy of vaporisation which limits the evaporation of the solvent. According to UN regulations (UN3163), that classifies it as non-flammable liquefied gas, the solvent is shipped in pressurerated cylinders. It also prevents loss of product by evaporation during transportation and storage. In addition to the environmental friendly attributes when compared to HFE7100, Solstice1 PF has a lower cost of about a third on a single unit which increases to about a half cost-saving on bulk orders (Fig. 2). 3.2. Laboratory trials Split depletion series were done to compare the effectiveness of HFE7100 and Solstice1 PF as the amino acid reagent carriers. Each half of the depletion series was treated with a different processing technique and then recombined. For both ninhydrin-HFE7100 and ninhydrin-Solstice1 PF treatment only the first few depletions (up to the fourth) were observed (Fig. 3). The fingermarks were weakly visible but no obvious difference was seen between HFE7100 and Solstice1 PF ninhydrin formulations. There was no significant quality differences between the split depletion series halves of fingermarks recovered with DFO and 1,2-IND-HFE (Fig. 4b) and 1,2IND in both solvents (Fig. 4c). A slightly difference in fluorescence intensity was observed from the camera response but not visually. 3.3. Pseudo-operational trial A pseudo-operational trial was then set-up following the successful results with split depletions under laboratory conditions. A pseudo-operational trial can be used to "establish whether the results obtained in laboratory trials are replicated on articles/surfaces typical of those that may be submitted to a fingerprint laboratory, or to distinguish between closely equivalent formulations that cannot be separated in laboratory trials" [24]. The number of fingermarks detected for each process is presented in Tables 2 and 3. Figs. 5 and 6 are the graph representatives of Table 2. The results obtained show that both ninhydrin and 1,2-IND are comparable for the two carrier solvents tested, HFE7100 and Solstice1 PF. There are slightly more fingermarks developed with ninhydrin-HFE7100 (3.6% more) than with ninhydrin-Solstice1 PF, whereas 1,2-IND-Solstice1 PF appeared to develop the highest 56 I. Olszowska et al. / Forensic Science International 284 (2018) 53-64 Table 1 Physical properties of three different carrier solvents. Chemical name Honeywell Solstice1 PF performance fluid Trans-1-chloro-3,3,3-trifluoropropene 1233zd 3M Novec HFE7100 Methoxy-nonafluorobutane Chemical family Chemical formula Chemical structure Hydrochlorofluoro-olefin (HCFO) CF3-CHCClH Hydrofluoroether (HFE) C4F9OCH3 (mixture of two isomers) CFC-113 1,1,2-Trichloro-1,2,2trifluoroethane Chlorofluorocarbon (CFC) Cl2FC-CClF2 Molecular weight Appearance Boiling point (C) Latent heat of vaporisation at bp (kJ/kg) Freezing point (C) Vapour pressure at 25 C (kPa) Liquid density at 25 C (g/mL) Surface tension at 25 C (mN/m) Viscosity at 25 C (mPa s) Wetting index: 1000 x density/(surface tension viscosity) Solubility of water in solvent at 25 C (ppmv) Solubility of solvent in water (ppmv) Flash point (C) Flammability range in air Atmospheric lifetime Occupational exposure limit (ppm) Global warming potentiala Ozone depletion potentialb Cost ()/L (inclusive of VAT)c (minimum order) Cost ()/L (inclusive of VAT)c (bulk order) 130 Colourless 19 194 107 126 1.26 12.7 0.45 220 460 1900 None None 26 days 800 1 0.00 64.66 (6 kg drum equates to 4.76 L which costs 307.80) Delivery charge 36 43.87 (4 6 kg drums equate to 19.05 L which costs 835.20) Delivery charge 36 250 Colourless 61 112 135 28 1.52 13.6 0.61 183 95 12 None None 4.1 years 750 320 0.00 90.93 (5.4 kg drum equates to 3.55 L which costs 322.80) Free delivery 85.33 (15 kg drum equates to 9.87 L which costs 842.24) Free delivery a GWP-100 year Integration Time Horizon (ITH). b CFC-11 = 1.0. c Prices as given by Samuel Banner Chemicals and Severn Biotech for Solstice1 PF and HFE7100 respectively (September 2017). 187 Colourless 48 146 35 44 1.56 17.3 0.68 133 110 170 None None 85 years 1000 6000 0.80 N/A N/A number of fingermarks which is 1.0% higher than with 1,2-INDHFE7100 (3.8% higher for the Solstice1 PF formulation when taking into account ninhydrin sequencing). Fig. 7 represents the cumulative increase of fingermarks detected by batches of Fig. 2. Solstice1 PF 6 kg container. 100 samples. Figs. 8-10 show several examples of enhanced latent marks with the different processes employed in this study. 3.3.1. Before ninhydrin sequencing There is little difference in the number of fingermarks detected when comparing the two carrier solvents for ninhydrin and 1,2IND for each substrate. 1,2-IND-HFE7100 detected considerably higher amount of fingermarks on envelopes whereas the opposite was true for newspapers and 1,2-IND-Solstice1 PF. A further observation is that ninhydrin-Solstice1 PF developed more latent fingermarks on grey papers (44% more) as well as brown and grey envelopes (61% more). A second examination of ninhydrin developed marks after 10 days indicated an increase of approximately 11% in fingermark recovery. A higher number of additional marks using the ninhydrin-Solstice1 PF process was found on paper (8%) and newspaper (21%), whereas while using the ninhydrin-HFE7100 formulation the quantity of new marks reached 7% and 15% respectively. An equivalent number of new marks on magazines/leaflets (11%) was observed whereas an increase of 11% was detected with envelopes treated with the ninhydrin-HFE7100 formulation and 8% for the ninhydrin-Solstice1 PF formulation. DFO (HFE formulation) was included in this study as a validation study for its possible replacement with 1,2IND [23]. The results show that the total number of fingermarks developed with the DFO formulation is 20% lower in comparison to 1,2-IND-HFE7100 and 21% lower than 1,2-IND-Solstice1 PF I. Olszowska et al. / Forensic Science International 284 (2018) 53-64 57 Fig. 3. Depletion series on paper: ninhydrin-HFE7100 (lower half), ninhydrin-Solstice1 PF (upper half). Fig. 4. Depletion series on paper by different donors: (a) DFO (left) and 1,2-IND-HFE (right); (b) DFO (left) and 1,2-IND-Solstice1 PF (right); (c) 1,2-IND-HFE (left), 1,2-INDSolstice1 PF (right). formulation. The HFE7100 and Solstice1 PF formulations for 1,2IND developed 1.2 times as many marks as DFO. In contrast, a recent CAST study [23] on 432 porous items (paper and cardboard) reported that 1,2-IND-HFE7100 (same formulation as this study) developed 1.6 times as many marks as DFO. 3.3.2. After ninhydrin sequencing The DFO-ninhydrin sequence produced an increase of 27% new marks and 60% of DFO recovered marks were also visualised with ninhydrin treatment. Ninhydrin sequencing of 1,2-IND enhanced fingermarks yielded an increase of 20% and 23% for the HFE7100 and Solstice1 PF formulations respectively. Furthermore, 63% of previously recovered 1,2-IND-HFE7100 marks and 66% of 1,2-IND-Solstice1 PF marks were also visualised with ninhydrin treatment. DFO-ninhydrin sequencing was particularly effective on newspaper (61% new marks) whereas 1,2-IND-ninhydrin sequencing was effective for magazines (72% and 61% new marks for HFE and Solstice1 PF respectively). 58 I. Olszowska et al. / Forensic Science International 284 (2018) 53-64 Table 2 Total number of fingermarks detected for each process and substrate (including sequencing). Surface A B C C (DFO/NIN) C (NIN new) D D (IND/NIN) D (NIN new) E E (IND/NIN) E (NIN new) Envelopes 65 60 115 71 37 Papers 318 311 503 300 114 Magazines 45 37 47 29 14 Newspapers 65 68 33 21 20 134 80 32 594 386 94 39 24 28 72 37 15 101 73 20 587 387 124 51 41 31 108 56 24 Total 493 476 698 421 185 839 527 169 847 557 199 Table 3 Cumulative number of fingermarks detected for each process and substrate. Batch Envelopes Paper Magazines Newspaper A B C D E A B C D E A B C D E A B C D E 1 16 12 34 58 40 49 39 65 80 51 0 0 1 0 1 8 6 1 4 7 2 30 25 71 86 57 79 71 135 163 119 3 2 1 9 16 14 10 7 14 14 3 36 29 89 100 62 96 93 193 242 199 11 5 2 21 24 15 10 9 14 18 4 37 34 96 111 72 116 108 221 297 277 15 6 9 25 33 16 13 16 23 31 5 43 43 115 125 84 135 127 265 355 348 34 26 36 51 71 31 33 36 44 70 6 45 46 118 131 88 160 148 337 434 418 41 28 43 57 77 33 33 36 46 71 7 46 47 131 136 98 187 185 417 502 507 44 36 53 57 78 40 42 39 56 95 8 48 49 144 152 107 243 236 500 588 608 45 37 58 57 78 43 44 42 66 109 9 52 54 145 156 109 262 255 551 637 659 45 37 61 64 80 54 58 44 74 121 10 65 60 152 166 121 318 311 617 688 711 45 37 61 67 82 65 68 53 87 132 Fig. 5. Number of detected fingermarks for each process on all substrates. 3.3.3. Zinc toning A zinc toning solution was prepared using both HFE7100 and Solstice1 PF. Successful enhancement was achieved for both formulations on split depletions as well as on marks recovered during the pseudo-operational trial (Fig. 11). 3.4. Solvent usage 500 mL solution were prepared for all formulations just prior to use. This was enough to treat approximately 200 samples. During the pseudo-operational study, the age of the solution varied from one to fourteen days; however, ageing consistency across each batch of 100 samples was maintained. Solutions were stored in a refrigerator at 4 C with parafilm on the bottle caps and were allowed to reach room temperature prior to use. Preliminary trials showed that the Solstice1 PF working solutions for ninhydrin and 1,2-IND were still effective after 6 months. All solutions showed good stability and no precipitation or phase separation was observed. The total amount of solvent used during the pseudooperational trial of 1000 samples is given in Table 4. For the ninhydrin and 1,2-IND formulations, an average of about 20% more solvent was required for Solstice1 PF as compared to HFE7100 which may be explained by the lower boiling point of Solstice1 PF. There appears to be no correlation between the I. Olszowska et al. / Forensic Science International 284 (2018) 53-64 59 Fig. 6. Number of detected fingermarks for each process and substrate. Fig. 7. Cumulative number of fingermarks detected on all substrates for each process. quantity of solvent used for sample processing and weather conditions like temperature or humidity. The temperature and humidity in the laboratory were not controlled; however, external temperatures and relative humidity ranged from 11 to 19 C and 35-95% respectively during the trial. There were slight differences in solvent usage between each batch which may be due to varying sample size, sample wetness or porosity. The ninhydrinHFE7100 solution became cloudy after processing approximately 25 samples. This may occur due to sample contaminants or ninhydrin precipitation caused by solvent evaporation. For the 1,2IND-HFE7100 formulation no cloudy solution was noticed; however, the solution became slightly milky when the solvent was left to evaporate completely. DFO-HFE solution remained clear during the processing of samples. When the solution was left to evaporate, yellow oily droplets appeared on the surface. These droplets are formed due to water from the samples which is immiscible with the HFE solvent. For the ninhydrin and 1,2-IND Solstice1 PF formulations there was no issues with cloudy solutions, oily droplets, phase separation or reagent precipitation. Two magazine samples were observed to release some dye during treatment with 1,2-IND-Solstice1 PF. Due to the low boiling point of Solstice1 PF, shallow troughs with a curved, corrugated bottom surface should be used to minimise evaporation. This is also advised for solutions prepared 60 I. Olszowska et al. / Forensic Science International 284 (2018) 53-64 Fig. 8. Latent fingermarks enhanced with ninhydrin-HFE7100 (a,b) and ninhydrin-Solstice1 PF (c,d) on paper (a,c) and on newspaper (b,d). Fig. 9. Latent fingermarks enhanced with DFO on various substrates: envelope (a); paper (b); magazine (c) and newspaper (d). I. Olszowska et al. / Forensic Science International 284 (2018) 53-64 61 Fig. 10. Latent fingermarks enhanced with 1,2-IND-HFE7100 (a,b) and 1,2-IND-Solstice1 PF (c,d) on paper (a,c) and on newspaper (b,d). Fig. 11. Depletion series on paper: ninhydrin-HFE7100-zinc toning (lower half), ninhydrin-Solstice1 PF-zinc toning (upper half). with HFE-7100 [21]. To further minimise evaporation, solutions prepared with Solstice1 PF could be prepared just prior to use, otherwise appropriately sealed bottles should be used to store solution in a refrigerator. The fact that Solstice1 PF is shipped in pressure-rated cylinders prevents loss of product by evaporation during transportation and storage. 3.5. Ink diffusion The common ink constituents are a mixture of dyes, resins and carrier components such as glycol-based solvents or water. Exposure to polar solvents of these constituents may cause the ink to run and diffuse [26]. An assessment of the diffusion properties for the Solstice1 PF and HFE formulations was carried out. A random selection of 14 different ink types and colours was prepared on A4 white paper and treated with the different formulations. For 1,2-IND, two writing implements, Staedtler (black ink felt-tip pen) and Apex (blue ball-point pen), showed minimal ink running when treated with Solstice1 PF but not with HFE when observed under white light; however, under fluorescence examination, ink diffusion was observed for both carrier solvents (Fig. 12). No ink diffusion was observed when Table 4 Solvent usage for the pseudo-operational trial. Process Solvent usage/mL A Ninhydrin (HFE-7100) 2150 B Ninhydrin (Solstice1 PF) 2500 C DFO (HFE/7100/71DE) 2100 D 1,2-IND (HFE-7100) 1945 E 1,2-IND (Solstice1 PF) 2480 62 I. Olszowska et al. / Forensic Science International 284 (2018) 53-64 Fig. 12. A4 white paper with various inks as viewed under white light and fluorescence (blue-green light and 529 nm orange filter) after treatment with 1,2-IND: HFE7100 (a, b) and Solstice1 PF (c,d). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.) Fig. 13. Split paper sample from the pseudo-operational trial treated with ninhydrin: HFE formulation (bottom) and Solstice1 PF formulation (top). Solstice1 PF was used on its own suggesting that the polar components (e.g. methanol, acetic acid), although in small quantities, in the 1,2-indanedione formulation also play a role in the minimal ink diffusion observed. Ink diffusion was also monitored during the pseudo-operational trial. Fig. 13 shows a split paper sample with no ink diffusion observed, the lower half treated with ninhydrin-HFE7100 formulation and the upper half treated with the ninhydrin-Solstice1 PF formulation. The results indicated that neither HFE nor Solstice1 PF caused diffusion of handwritten or printed inks. From the 1000 samples in the pseudo operational trial, two samples showed slight ink diffusion. I. Olszowska et al. / Forensic Science International 284 (2018) 53-64 63 Fig. 14. A split handprint treated with iodine fuming with no fixing (right) and fixing with a-naphthoflavone- Solstice1 PF (left). 3.6. Iodine fixing solution An iodine fixing solution was prepared in both carrier solvents to assess their suitability to fix iodine treated marks on paper. Both solvents performed as expected where the fixative solution of a-naphthoflavone provided a blue colour enhancement to provide further contrast. Fig. 14 shows an example of a split handprint where one side was only fumed with iodine (right) and the other side was fumed with iodine followed by fixing with a a-naphthoflavone solution prepared with Solstice1 PF (left). 4. Conclusions As the EU is considering a ban on some of the hydrofluorinated solvents, including HFE7100, research into alternative solvents used in fingermark enhancement techniques is required. This study assessed Solstice1 PF as a possible replacement to HFE7100 for the preparation of various chemical formulations used in the development of latent fingermarks. A pseudo-operational trial of 1000 porous samples showed that the number of marks detected by ninhydrin and 1,2-IND formulations for both carrier solvents is comparable. Both solvents are fluorinated and non-ozone depleting; however, Solstice1 PF has a much lower GWP and atmospheric lifetime as well as a higher wetting index (lower surface tension). Furthermore, Solstice1 PF can have a cost saving of about 50% at current prices although an average of 20% more solvent was used during the pseudo-operational trial of 1000 samples. Ink diffusion for both solvents was comparable with minimal ink running. Although it is recognised that further research is required, this study shows that Solstice1 PF is a viable substitute to HFE7100 as a carrier solvent in a number of chemical formulations used in the visualization of latent fingermarks. The increased detection rate and the reduction of heating time (10 vs 20 min) of 1,2-IND when compared to DFO provides support for the potential replacement of DFO with 1,2-IND as a category A process. Acknowledgement The authors would like to thank the European Union Erasmus Student Mobility programme for providing financial support as a contribution for travel and subsistence costs for Izabela Olszowska. References [1] Regulation (EU) No 517/2014, Regulation (EU) No 517/2014 of the European Parliament and of the Council of 16 April 2014 on fluorinated greenhouse gases and repealing Regulation (EC) No 842/2006, Off. J. Eur. Union (2014) L 150 195- 230. [2] S. Oden, B. von Hofsten, Detection of fingerprints by the ninhydrin reaction, Nature 173 (1954) 449-450. [3] D.A. Crown, Development of latent fingerprints with ninhydrin, J. Crim. Law Criminol. Police Sci. 60 (1969) 258-264. [4] J.R. Morris, G.C. Goode, NFN -- an improved ninhydrin reagent for detection of latent fingerprints, Police Res. Bull. 24 (1974) 45-53. [5] W.J. Watling, K.O. Smith, Heptane: an alternative to the freon/ninhydrin mixture, J. Forensic Identif. 43 (1993) 131-134. [6] D.F. Hewlett, V.G. Sears, Replacements for CFC113 in the ninhydrin process: part 1, J. Forensic Identif. 47 (1997) 287-299. [7] D.F. Hewlett, V.G. Sears, S. Suzuki, Replacements for CFC113 in the ninhydrin process: part 2, J. Forensic Identif. 47 (1997) 300-331. 64 I. Olszowska et al. / Forensic Science International 284 (2018) 53-64 [8] W.O. Jungbluth, Replacement for Freon 113, J. Forensic Identif. 43 (1993) 226- 233. [9] D.F. Hewlett, V.G. Sears, An operational trial of two non-ozone depleting ninhydrin formulations for latent fingerprint detection, J. Forensic Identif. 49 (1999) 388-396. [10] A. Petruncio, A comparative study for the evaluation of two solvents for use in ninhydrin processing of latent print evidence, J. Forensic Identif. 50 (2000) 462-469. [11] G.W. Wilson, Pseudo-operational Trial to Compare 2 Solvents in Ninhydrin Working Solution During the Development of Fingerprints on Porous Surfaces, Staffordshire University, 2009. [12] A. Harrison, Investigation into an Alternative Solvent for Ninhydrin, Staffordshire University, 2007. [13] C.J. Lennard, P.A. Margot, M. Stoilovic, R.N. Warrener, Synthesis of ninhydrin analogues and their application to fingerprint development: preliminary results, J. Forensic Sci. Soc. 26 (1986) 323-328. [14] R.J. Heffner, M.M. Joulli, A synthesis of two novel benzo[f]ninhydrin analogs: 6-methoxybenzo[f]ninhydrin and thieno[f]ninhydrin, Synth. Commun. 21 (1991) 1055-1069. [15] D.B. Hansen, M.M. Joullie, The development of novel ninhydrin analogues, Chem. Soc. Rev. 34 (2005) 408-417. [16] J. Almog, A. Klein, I. Davidi, Y. Cohen, M. Azoury, M. Levin-Elad, Dual fingerprint reagents with enhanced sensitivity: 5-methoxy- and 5-methylthioninhydrin, J. Forensic Sci. 53 (2008) 364-368. [17] N. Porpiglia, S. Bleay, L. Fitzgerald, L. Barron, An assessment of the effectiveness of 5-methylthioninhydrin within dual action reagents for latent fingerprint development on paper substrates, Sci. Justice 52 (2012) 42-48. [18] R. Grigg, T. Mongkolaussavaratana, C.A. Pounds, S. Sivagnanam, 1,8-Diazafluorenone and related compounds. A new reagent for the detection of alpha amino acids and latent fingerprints, Tetrahedron Lett. 31 (1990) 7215-7218. [19] R.S. Ramotowski, A.A. Cantu, M.M. Joullie, O. Petrovskaia, 1,2-Indanediones: a preliminary evaluation of a new class of amino acid visualising compounds, Fingerpr. Whorld 23 (1997) 131-140. [20] D.B. Hauze, O. Petrovskaia, B. Taylor, M.M. Joullie, R.S. Ramotowski, A.A. Cantu, 1,2-Indanediones: new reagents for visualizing the amino acid components of latent prints, J. Forensic Sci. 48 (1998) 744-747. [21] Home Office, Fingermark Visualisation Manual, (2014) . [22] CAST, Fingermark Visualisation Newsletter, (2016) February. [23] CAST, Fingermark Visualisation Newsletter, (2017) March. [24] V.G. Sears, S.M. Bleay, H.L. Bandey, V.J. Bowman, A methodology for finger mark research, Sci. Justice 52 (2012) 145-160. [25] IFRG, Guidelines for the assessment of fingermark detection techniques, J. Forensic Identif. 64 (2014) 174-200. [26] J.T. Stimac, The search for safe, non-running solvents: a brief history, J. Forensic Identif. 50 (2000) 455-461.