Optimisation and evaluation of 1,2-indanedione for use as a fingermark reagent and its application to real samples

1,2-indanedione is an emerging fingermark reagent used on porous surfaces. The general consensus is that this reagent is at least as sensitive as DFO, with some research showing higher sensitivity for 1,2-indanedione as opposed to DFO. However, a number of discrepancies existed in the literature as to which formulation and which development procedure produces optimal results. This project set out to investigate the best formulation and development procedure under Australian conditions, encompassing all published recommendations as well as some novel approaches. 1,2-indanedione formulations were compared with respect to initial colour, fluorescence, concentration of reagent, acetic acid concentration, and the effect of different carrier solvents. Numerous development conditions were investigated, including a conventional oven, a heat press and humidity. Further enhancement using metal salt treatment and liquid nitrogen was also evaluated. The heat press set at 165 degrees C for 10s proved to give the best initial colour and most intense luminescence. Secondary metal salt treatment improved initial colour and luminescence. The Polilight, the VSC 2000, and the Condor Chemical Imaging macroscope have been used to detect the fingerprints developed with 1,2-indanedione on a variety of high- and low-quality porous and semi-porous surfaces, with impressive results overall. Laboratory and field tests were conducted to compare 1,2-indanedione with DFO and ninhydrin as well as to investigate the position of 1,2-indanedione in the sequence of reagents for fingermark detection on porous surfaces. Overall, 1,2-indanedione proved to be a viable alternative to traditional methods for the detection of fingermarks on porous surfaces, with more fingermarks being developed using this reagent on real samples than both DFO and ninhydrin and a combination of the two reagents.     

热敏纸表面上汗潜指纹的显现

茚三酮溶液显现法是显现普通纸表面汗潜指纹的常用方法。但是由于热敏纸表面涂有热敏涂料,使得上述方法在该客体表面汗潜指纹的显现中难以奏效。不过,在此方法基础上改良发展而来的1,2茚二酮法、二甲基氨基肉桂醛法、过量丙酮冲洗法、半醇酮茚显现法等4种方法能取得较好效果。     

胺端基型CdS／PAMAM潜在显现指印的应用

目的探索一种新型纳米荧光材料的制备方法及其在潜在指印显现方面的应用前景。方法以聚酰胺-胺（PAMAM）树形分子为模板，原位合成CdS纳米簇。并使用荧光光谱法对产物进行表征：应用这种新型荧光材料对多种客体表面、不同陈旧程度的潜在指印进行显现．并将显现结果与传统荧光染料进行比对。结果该荧光材料在365nm紫外光激发下可以发出很强的可见荧光：与传统的荧光染料相比。-NH2端基型CdS／PA—MAM可以同指印残留物进行靶向结合．其荧光强度高、背景干扰小，指印纹线与客体反差大。结论-NH2端基型CdS／PAMAM可以有效地显出非渗透性客体表面的潜在指EP。     

Mass spectra and time-resolved fluorescence spectroscopy of the reaction product of glycine with 1,2-indanedione in methanol

The reaction products of 1,2-indanedione (a new fluorescent fingerprint reagent) with glycine in methanol, at room temperature have been studied using excitation and emission and time-resolved fluorescence spectroscopy. Gas chromatography-mass spectroscopy (GC/MS) has also been used to determine which compounds are formed. Reaction products were identified using GC/MS as 2-carboxymethyliminoindanone (MW=203 g) and 1,2-di(carboxymethylimino)indane (MW=260 g). Identified compounds show room temperature fluorescence lifetimes of tau(1)=7.69 ns and tau(2)=1.27 ns. It is not clear yet which compound is having fluorescence lifetime of 7.69 ns and which one is showing 1.27 ns.     

LED多波段光源显现人民币上潜指印的研究

目的研究显现、提取遗留在人民币上潜在指印的方法。方法采用荧光试剂罗丹明6G对人民币进行染色处理,以LED多波段光源输出的波长为520nm的绿光照射检材,透过580nm的带通型干涉滤光镜观察指印的显现效果,并拍照提取。结果获得亮纹线暗背景的指印图像,指印纹线清晰,反差良好,特征丰富,具备良好的检验鉴定条件。结论 LED多波段光源输出的波长为520nm的绿光与罗丹明6G染色指印的吸收特性吻合,是显现、提取遗留在人民币上潜在指印的良好光源。     

PAMAM G7.0的制备及在非渗透性表面手印显现中的应用

目的探索一种非渗透性表面手印显现的新方法。方法根据现有方法合成第七代聚酰胺-胺（PAMAM G7.0）树形分子材料,并使用荧光光谱法对产物进行荧光测试;将合成材料对多种客体表面、不同遗留时间的手印进行显现,并将显现结果与粉末法和传统的荧光染料法进行比对。结果实验表明该荧光材料在365nm光激发下可以发出较强的可见荧光;与粉末法和传统的荧光染料法相比,PAMAM G7.0可以同手印残留物进行高选择性结合,手印纹线与背景之间的反差大。结论PAMAMG7.0可以有效地显出非渗透性客体表面的手印。     

Visualization of Aged Fingerprints with an Ultraviolet Laser

Detection of aged fingerprints is difficult because they can degrade over time with exposure to light, moisture, and temperature. In this study, aging fingerprints were visualized by time‐resolved spectroscopy with an ultraviolet‐pulsed laser. Fingerprints were prepared on glass slides and paper and then stored under three lighting conditions and two humidity conditions for up to a year. The fluorescence intensities of the fingerprints decreased with time. Samples were stored in the dark degraded less than in sunlight or under a fluorescent lamp. Samples were stored under low humidity degraded less than under moderate humidity. As the storage period increased, a fluorescence emission peak appeared that was at a longer wavelength than the peak visible in earlier spectra. This peak was used for visualization of an aged fingerprint over time. An image of the fingerprint was not initially visible, but an image appeared as the time since deposition of the fingerprint increased.     

Fingerprint reagents with dual action: color and fluorescence

We define "dual fingerprint reagents" as chemical formulations that produce with latent fingerprints in one stage impressions that are both colored and fluorescent. Solutions containing ninhydrin and group IIb metal salts appear to be true dual reagents. Application of these formulations to latent fingerprints on paper is as efficient as the two-step process beginning with ninhydrin and followed by treatment with metal salt. In the color mode, fingerprint detectability with the two ninhydrin-metal salt reagents (one with zinc chloride and the other with cadmium chloride) is comparable with that of ninhydrin itself, in spite of the difference in color. The sensitivity is significantly higher in the fluorescence mode. To view the latent impressions the exhibits are treated with ninhydrin-metal salt reagents and observed under white light illumination and under fluorescence conditions. Cooling to liquid nitrogen temperature enhances the fluorescence considerably. In the shorter wavelength domain, ninhydrin-metal salt reagents exhibit higher sensitivity than the recently reported dual reagent, genipin. The latter is advantageous, however, in the longer wavelength domain, on paper items with strong self-fluorescence, such as brown wrapping paper or paper printed with fluorescent ink. Upon reduction of the ninhydrin concentration 10-fold, ninhydrin-metal salt formulations become purely fluorogenic reagents; no color is noticed but the fluorescence is as intense as with concentrated solutions. Working at lower concentrations is an advantage from ecological and economical viewpoints.     

ABTS: a safe alternative to DAB for the enhancement of blood fingerprints

The use of 2,2'-azino-di-[3-ethylbenzthiazolinesulfonate(6)] diammonium salt (ABTS) for the enhancement of fingerprints in blood has been investigated. Optimal pH conditions and H2O2 concentrations have been determined using UV/Vis spectroscopy. ABTS is an effective and safe noncarcinogenic (though more expensive) alternative to the presently used 3,3'-diaminobenzidine (DAB) for the development of blood fingerprints, especially on porous surfaces. The bright green color of the oxidized ABTS is an advantage on certain colored surfaces where the dark brown color of DAB does not stand out well from the background. Development with ABTS does not interfere with subsequent DAB treatment, making ABTS a "nothing-to-lose" reagent. ABTS can be used after ninhydrin treatment, but the reverse is not the case.     

掺杂Cd的水溶性荧光ZnSe/MPA量子点显现胶带手印方法

目的探索水溶性荧光量子点溶液——掺杂镉的硒化锌（ZnxCd（1-x）Se）对胶带手印的显现方法。方法以巯基丙酸（MPA）为修饰剂合成了掺杂Cd的水溶性荧光ZnSe/MPA量子点,利用它显现水浸胶带及粘连胶带上的油汗指印,并在365nm下拍照成像。结果良好的显现出水浸胶带上的指印以及粘连胶带上的指印。与常规方法相比,优势更为明显。结论水溶性荧光量子点ZnxCd（1-x）Se溶液显出的指印纹线细腻流畅,在法庭科学领域具有很好的应用前景。     

Genipin, a novel fingerprint reagent with colorimetric and fluorogenic activity, part II: optimization, scope and limitations

Genipin, a hydrolytic product of geniposide extracted from gardenia fruit, was thoroughly studied as a potential fingerprint reagent, and optimal conditions for fingerprint development have been determined. Latent fingerprints on paper items that have been treated with a non-ink running formulation containing 0.17% of the reagent, showed up as both colored and fluorescent images. On brown wrapping paper and on papers with highly luminescent backgrounds, genipin developed more visible and clearer prints than did classical reagents such as ninhydrin or DFO. Another potential advantage of genipin is that it is totally harmless and an environmentally friendly reagent.     

An evaluation of the effect of incorporating metal salts into 1,8 diazafluoren-9-one (DFO) formulations for fingermark enhancement

A study into the modification of 1,8-diazafluoren-9-one (DFO) formulations by the additions of metal salts into the working solution is reported. Similar additions have been found to increase the fluorescence of marks developed using other amino acid reagents including 1,2-indandione and the ninhydrin analogue 5-methylthioninhydrin. It was found that adding zinc chloride to give a 1:1 ratio of zinc ions:DFO molecules gave optimum fluorescence, and improvements in performance over the standard DFO formulation were achieved. Attempts to produce equivalent formulations with iron, nickel and palladium chlorides were unsuccessful. In a comparative trial with a 1,2-indandione-zinc formulation on brown paper and cardboard substrates, 1,2-indandione-zinc gave superior results and it was decided to focus further research on this reagent instead of DFO-zinc.     

A scanning beam time-resolved imaging system for fingerprint detection

A highly sensitive confocal scanning-beam system for time-resolved imaging of fingerprints is described. Time-resolved imaging is a relatively new forensic procedure for the detection and imaging of latent fingerprints on fluorescent substrates such as paper, cardboard, and fluorescent paint. Ordinary fluorescent imaging of latent fingerprints on these surfaces results in poor contrast. Instead, the specimens are treated with a phosphorescent dye that preferentially adheres to the fingerprint which allows time-resolved discrimination between the fingerprint phosphorescence and the background fluorescence. Time resolved images are obtained by synchronizing the digital sampling of the specimen luminescence with the on-off cycle of the chopped illumination beam. The merit of this technique is illustrated with high contrast images of fingerprints obtained from the fluorescent painted surface of a Coke can.     

Improved method for DFO development of latent fingerprints

A new formulation has been developed for DFO stock solution. The working DFO solution, based on the new stock solution, appears to be more stable, has a longer shelf life, and has little effect on inks (and therefore does not cause inks to run). Photoluminescence spectra of latent fingerprints developed with DFO reagent have been measured and the choice of filters for excitation and emission (barrier) have been derived from these measurements. Comparisons of latent fingerprints developed with ninhydrin and DFO have been made using various papers and at various intensities. These comparisons show the much greater sensitivity of DFO developed latent fingerprints. Although enhanced ninhydrin and DFO develop latent fingerprints with similar sensitivity, the DFO process is much simpler.     

Fluorescence of 1,2‐Indanedione with Amino Acids Present in the Fingerprint Residue: Application in Gender Determination

1,2‐indanedione is used for latent fingerprint visualization on porous surfaces. In this paper, fluorescence spectra of 1,2‐indanedione after reacting with 21 individual amino acids present in latent fingerprints residue were measured in water‐methanol solutions. The fluorescence intensity depends on the amino acid used, while the fluorescence peak does not change much. The concentration of amino acids in fingerprint residue in females is almost the double of their concentration in males. This property combined with fluorescence of 1,2‐indanedione‐amino acids compounds is used for gender determination, by comparing the fluorescence intensity peaks in the same experimental conditions. In this preliminary study, the fluorescence signal from the samples representing females was almost two times the signal for samples representing males. In addition to the reduction by almost 50% of the number of suspects in a criminal research case, these results could be helpful in gaining some knowledge about the papillary residue composition.     

Luminous lip-prints as criminal evidence

Luminescence is specially a useful property for the search of invisible evidences at the scene of a crime. In the latent fingerprints particular case, there are at one's disposal fluorescent reagents for their localization. The study of latent lip prints (that is lip prints from protective lipstick, or permanent or long-lasting lipstick that do not leave any visible marks) is more recent than fingerprints study. Because of the different composition of both types of prints, different reagents have been tried out on their developing. Although, lysochromes are particularly useful reagents to obtain latent lip prints, it may occur on coloured or multicoloured surfaces, the developing is not perceived due to contrast problems between the reagent and the surface where the print is searched. Again, luminescence offers the possibility to solve this problem. Nile Red is being studied as a potential developer for latent lip prints. The results on very old prints (over 1year) indicate that this reagent is highly efficient to get latent lip prints.     

Visualization of latent fingerprints using fluorescence lifetime imaging on paper emitting strong fluorescence

Latent fingerprints were successfully visualized using fluorescence lifetime imaging (FLIM) on paper which emits strong fluorescence with a lifetime close to that of fingerprints and thus from which it is difficult for time-resolved spectroscopy to visualize fingerprints. Latent fingerprint samples on paper were excited using a 450 nm or 532 nm nanosecond pulsed-laser, and time-resolved fluorescence images were obtained at a delay time of 6–16 ns in intervals of 1 ns, to the excitation pulse. The excitation beam was expanded using a lens, and the fluorescence from the fingerprints was captured using an intensified CCD camera. Because of the large fluorescence intensity of the background paper of approximately two to four orders of magnitude larger than that of the fingerprint, the fingerprint was not visualized on each fluorescence image by time-resolved spectroscopy. However, the fingerprint was visualized in a FLIM image constructed using a series of the fluorescence images for the case with the fluorescence intensity of the background paper being four orders of magnitude larger than that of the fingerprint. The difference in fluorescence lifetime in the FLIM image of the visualized fingerprint and background paper was in the order of 0.1 ns, which was an order of magnitude smaller than the inherent fluorescence lifetime of a few nanoseconds for the fingerprints and paper. It was demonstrated that, at a background fluorescence intensity with a certain order of magnitude larger than that of fingerprints, FLIM has the potential to visualize latent fingerprints which cannot be visualized by time-resolved spectroscopy.     

紫外激光技术显现潜在指印的研究

目的研究显现潜在指印的新技术。方法用自主研发的266nm短波紫外线输出的ND：YAG激光器作为激发光源激发渗透性客体表面的潜在指印,使指印发出荧光。结果能有效显现出亮纹线暗背景的潜在指印发光图像。结论利用该紫外激光技术可以显现纸张等渗透性客体表面的潜在指印。     

Luminescent visualization of latent fingerprints by direct reaction with a lanthanide shift reagent.

The utilization of the lanthanide shift reagent tris (6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedionato) europium (III) [Eu(fod)3] as a simple one-step reagent for the luminescent visualization of latent fingerprints has been investigated. UV excitation of Eu(fod)3-treated prints, achieved by using a hand-held UV lamp or a Polilight, results in an orange emission at 614 nm. Time-resolved imaging is not required for visualization. Visualization of latent fingerprints on paper under the conditions used, although good, was found to be inferior to that obtained by standard DFO (1,8-diazafluoren-9-one) treatment, whereas visualization of prints obtained on aluminum drink cans and galvanized iron proved superior to that obtained by Superglue/panacryl treatment. Eu(fod)3 treatment can also be used first without compromising subsequent ninhydrin or DFO treatment, making it a 'nothing-to-lose" reagent.     

Photoluminescent semiconductor nanocrystals for fingerprint detection

The concept of utilizing photoluminescent semiconductor nanocrystals for latent fingerprint detection, especially in concert with phase-resolved imaging for background fluorescence suppression, is reduced to practice with CdS nanocrystals that are capped with dioctyl sulfosuccinate. The nanocrystals are dissolved in heptane or hexane and are applied in much the same way as staining with fluorescent dye, on articles that have been pre-fumed with cyanoacrylate ester and also on the sticky side of electrical tape without pre-fuming. Since CdS can form a photoluminescent nanocomposite with dendrimers, a feasibility examination of dendrimer tagging of fingerprints has also been conducted.