Fluorescent TiO2 powders prepared using a new perylene diimide dye: applications in latent fingermark detection

A new, highly fluorescent dye was synthesised using oleylamine combined with a perylene dianhydride compound. The new dye was characterised by 1H NMR, UV-vis spectroscopy and fluorescence spectroscopy as well as quantum yield. The dye was absorbed onto titanium dioxide nanoparticles for use as a fingerprint detection powder. The new fluorescent powder was applied to latent fingermarks deposited onto different non-porous surfaces and compared with commercial fluorescent powders. The powder exhibits strong fluorescence at 650-700 nm under excitation at 505 nm. On glass surfaces, the new powder gave images showing tertiary-level detail of the fingermark ridges with almost no background development. Compared with current magnetic fluorescent powders, the new powder was slightly weaker in fluorescence intensity but produced significantly less background development, resulting in good contrast between the fingermark and the substrate.     

Identification and dating of the fountain pen ink entries on documents by ion-pairing high-performance liquid chromatography

A novel approach for the identification and dating of the fountain pen ink entries on paper has been established by ion-pairing high-performance liquid chromatography (IP-HPLC). Twelve black and six red fountain inks have been collected, and their ink entries have been prepared by drawing lines on paper. The chromatographic conditions for separation of their dye components after extraction with solvents were optimized. Under the optimized conditions, the 18 fountain pen inks were differentiated individually by comparing the number of detectable main or minor dye components, and the relative peak intensities of each component. The ink entries were artificially and naturally aged, and the analysis results showed that the ink dye components were significantly decomposed when exposed to UV or fluorescent light compare to those of inks stored under natural condition. The changes of the relative peak height for the dye components were linearly related to the aging time, especially under natural aging conditions. The degradation characteristics of the dye components under different aging conditions provide scientific evidences for dating of the suspicious fountain pen ink entries on document.     

Thin layer chromatography/fluorescence detection of 3,4-methylenedioxy-methamphetamine and related compounds

A rapid and sensitive method for the detection of six methylenedioxylatedphenethylamines, 3,4-methylenedioxymethamphetamine (MDMA); 3,4-methylenedioxyamphetamine; 3,4-methylenedioxyethylamphetamine; N-methyl-1-(3,4-methylenedioxyphenyl)-2-butamine; N-methyl-1-(3,4-methylenedioxyphenyl)-3-butamine; and 3,4-methylenedioxydimethylamphetamine, by thin-layer chromatography with fluorescence detection is proposed. These compounds form fluorophores on the developing plate following spraying with a reagent consisting of sodium hypochlorite, potassium hexacyanoferrate (III), and sodium hydroxide, and heating for 3 min at 100 degrees C. Blue fluorescent spots were observed under ultraviolet light in a wavelength range of 250-400 nm. The detection limits for MDMA and the above related compounds were 50 ng. The proposed method was effectively applied to the detection of MDMA in urine samples.     

刑事照相常用紫外光源照射对DNA检验的影响研究

目的探究刑事照相常用紫外光源照射不同客体上的血指印和汗潜指印后对DNA检验产生的影响。方法分别使用254nm和365nm紫外光源在不同照射距离,不同照射时间下对不同客体表面制备的原血指印、微量血指印和汗潜指印检材进行照射,随后进行DNA定量分析。结果原血指印经紫外照射后对DNA检验结果无显著影响,微量血指印和汗潜指印经紫外照射对后续DNA检验结果认定影响较大。结论紫外光波长越短、功率越大、照射距离越短、照射时间越长,对DNA检验结果的影响越大。     

Ultraviolet illumination as an adjunctive aid in dental inspection

Tooth-colored resin fillings have become increasingly popular as restorative materials. Their presence in the dentition presents a challenge to the clinician and the forensic odontologist, as detection of the fillings can be difficult both visually and radiographically. As they necessarily form part of the unique dentition of an individual, recognition of the resins is important for forensic identification. Alternative light sources have been used with success in various fields of forensic science. In recent years small LED flashlights emitting at specific wavelengths in the ultraviolet light (UV) range have been developed. Their low cost, small size, and ready availability makes their use practical in both forensic dental inspection and clinical settings. UV inspection is of interest because enamel, dentin and dental materials all have differing fluorescent properties when illuminated by UV light. It was one goal of this research to quantitatively assess the fluorescence properties of modern restorative resins in order to predict their behavior during inspection using UV illumination. The second goal was to demonstrate practical use of UV in dental inspection with examples of how different materials fluoresce. Quantitative measurements were obtained for optical emission wavelength and intensity for 15 modern resins using a spectrophotometer. Results indicated that resin brands fluoresce at different wavelengths and with varying intensities. Practical use and comparison of the flashlights revealed that the most useful excitation wavelengths for resin detection were in the UVA range (365 and 380 nm). Porcelain restorations and composite resin fillings exhibited different responses to these two wavelengths and thus use of both is recommended for forensic dental inspection.     

Statistical Evaluation of Alternative Light Sources for Bloodstain Photography

Bloodstain photography is important in forensic applications, especially for bloodstain pattern analysis. This study compares the enhancement effect of bloodstain photography using three different types of light source: fluorescent white light, near‐ultraviolet (UV) light‐emitting diode (LED) light, and 410 nm LED light. Randomized complete block designs were implemented to identify the lighting that would statistically produce the best enhancement results for bloodstains on different types of surfaces. Bloodstain samples were prepared on white cotton, brown carpet, tar road, and wood. These samples were photographed in darkroom conditions using a Canon EOS 50D digital SLR camera, with Canon EFS 60 mm f/2.8 Macro USM lens. Two‐way analysis of variance and Fisher's least significant difference test were used to analyze the contrast of the images. The statistical analysis showed that 410 nm light is the best among the tested lights for enhancing bloodstains on the tested surfaces, where the contrast of bloodstain to background was the highest.     

Instability of calcium channel antagonists during sample preparation for LC-MS-MS analysis of serum samples

1,4-Dihydropyridines calcium channel antagonists (1,4-DHP CCAs) are photolabile and the products of their photodecomposition have no pharmaceutical activity. In our previous work we have presented a screening procedure for eleven 1,4-DHPs in plasma by LC-MS-MS using multiple reaction motoring. The laboratory process includes preparation and storage of stock solutions, plasma storage, solid-phase extraction, reconstitution of extracts and storage time in an autosampler for LC-MS-MS analysis. Prior to validation of the analytical procedure, we have tested the stability of these compounds by exposure to light. Methanolic solutions have been exposed to laboratory and UV light and the stability of the compounds in plasma was tested by exposure of spiked plasma samples to laboratory light at room temperature. Stability during freeze-thaw cycles and stability during 2 month storage at -20 degrees C have been tested as well. Products of photodecomposition have been identified after forced degradation and the degree of degradation has been quantified using LC-UV-DAD and LC-MS-MS, respectively. A 96% degradation after only 2h has been observed when solutions of nifedipine or nisoldipine were exposed to laboratory light in clear glass vials. In plasma samples degradation was 25% in only 2h for both compounds. The main degradation product was produced by oxidation of the dihydropyridinic ring resulting in the pyridine analogue that has been described as the first metabolite in the metabolic pathway. Only minor degradation was found for the other tested compounds after 2h light exposure in methanolic solutions. Furthermore, lercanidipine and nicardipine were also degradated by esterhydrolysis. Several additional minor degradation products were found for the other tested 1,4-DHPs, however, some of them could not be identified. Preconditions for storage and handling of plasma samples prior to and during analysis for 1,4-DHP CCAs are suggested in order to avoid photodecomposition of the analytes.     

ZnS和ZnS:Cu无机紫外荧光材料的制备及其在汗潜手印显现中的应用

目的制备荧光强度高、客体适用性广、显现效果优良且合成方法简单的ZnS及ZnS:Cu无机紫外荧光材料,并将其用于汗潜手印的显现。方法通过一步溶液反应共沉淀法制备ZnS无机紫外荧光材料,并在ZnS材料中加入Cu^2+得到ZnS:Cu以改善荧光性质,将其应用于普通客体(白色捺印纸、载玻片、铁架台、乳白色花纹瓷砖表面、磨砂化学实验台面、不锈钢表面)和复杂客体(拼色花纹瓷砖、农夫山泉塑料标签和杂志封面铜版纸)上汗潜手印的显现,并与传统荧光粉末显现效果进行对比。结果ZnS材料具有荧光性,并且在ZnS材料中掺杂Cu^2+后得到的ZnS:Cu材料荧光强度增强,荧光光谱范围变广,稳定性提升。显现汗潜手印时,适用客体范围更广,并且可通过调节激发光的波长呈现不同的显现效果。结论通过在无机荧光材料ZnS中掺杂Cu^2+可改善材料的荧光范围,从而得到适用于不同客体上汗潜手印显现且效果更好的ZnS:Cu无机紫外荧光材料。     

Rapid,presumptive identification of seed-based toxins using direct analysis in real time mass spectrometry (DART-MS) and its variants

Detection of seed-based toxins is a need for forensic chemists when suspected poisonings occur. The evidence that is found is often physically unidentifiable, as the seeds are mashed to extract the toxin. This work investigates potential strategies for rapid detection of seed-based toxins and seed mashes containing these toxins using chemical signatures obtained by direct analysis in real time mass spectrometry (DART-MS). Seven toxins (digoxin, digitoxin, hypaconitine, hyoscyamine, lanatoside, oleandrin, and scopolamine) and six seeds containing these toxins were studied. While detection of four of the toxins was readily attainable, detection of digoxin, digitoxin, and lanatoside was hindered by the inability to thermally desorb these larger compounds under normal operating conditions. The use of DART-MS variants capable of higher desorption temperatures (thermal desorption (TD)-DART-MS and infrared thermal desorption (IRTD)-DART-MS) enabled detection of these compounds. Detection of toxins from direct analysis of seed mashes and methanolic seed mash extracts was found to be compound and technique dependent. Principal component analysis (PCA) of generated mass spectra enabled differentiation of seed species, even in cases where the toxins were undetectable.     

Genes involved in damage response caused by UV radiation in Ecuadorian population of different altitude regions

Ecuador has various regions at different altitudes. It is known that at high altitudes, organisms experience multiple stressors, including exposure to ultraviolet (UV) radiation. The UV radiation exposure increases when getting closer to the Equator line. Consequently, cities in the Ecuadorian inter-Andean region and located at 2,800-3,000 m above sea level (masl) are exposed to UV levels approximately 40% higher than those of the lowlands. UV light is a carcinogen that causes mutations, DNA damage and cellular apoptosis. However, the XPC, XPD and XPG genes encode proteins that repair DNA caused by UV radiation. The aim of this study was to evaluate the distribution of three polymorphisms (rs2228001, rs13181 and rs17655) involved in the response to the damage caused by UV radiation in the Ecuadorian populations of high and low altitudes, and thus, correlate the ancestral proportions of these populations. Results showed that the behavior of both groups located at different altitudes is similar. The ancestry of these groups exhibited that the Native American component prevails, and the European and African component varies.     

HPLC analysis of ballpoint pen inks stored at different light conditions

A method for comparison of ink entries on documents stored in different light conditions is presented. Various blue inks were exposed to light, both daylight and artificial light from fluorescent tubes. Inks were then extracted from the document and analyzed by HPLC (high performance liquid chromatography). Significant changes in composition were noted on exposure to light. These changes were followed by using ternary diagrams constructed for dyes generally present in blue-colored inks--Crystal Violet, Methyl Violet, and Tetramethyl Para Rosaniline. Also, the amount of the various compounds formed by decomposition of these dyes on exposure to light was measured and employed for comparison of inks. An example of the use of the proposed method in casework is given.     

An investigation into the persistence of textile fibres on buried carcasses

A significant amount of research has been carried out on fibres to aid the forensic scientist in determining the significance of these when found on a victim or suspect. This work has focused on open-air environments, and as such no research has been undertaken to examine the persistence of fibres on bodies in the burial environment.Wool and cotton fibres, known to fluoresce under ultraviolet (UV) light, were transferred onto the skin of four porcine (Sus scrofa) carcasses (two carcasses per fibre type). The number of fibres transferred was recorded from images taken under UV light. The remains were subsequently placed in four burial sites and left interred for 14 days. After this period the carcasses were excavated and lightly brushed down to remove the soil layer that had adhered to the skin. Once again photography under UV light was used to record the number of fibres which persisted on the skin.Results showed that after 14 days, wool and cotton fibres remain on the surface of the buried carcasses. In no circumstance was there a total loss of fibres suggesting that in such scenarios, the likelihood of finding fibres is high but the initial number of fibres transferred would be strongly diminished. This has important implications for both the excavation protocol for buried remains and the subsequent analysis for physical evidence.     

Blocks of colour IV: the evidential value of blue and red cotton fibres.

Samples of blue and red cotton fibres were examined using light and fluorescence microscopy as well as UV/VIS microspectrophotometry and fluorescence microspectroscopy. The degree of fluorescence and spectral variation was recorded. Particular attention was paid to the recurrence of certain spectral patterns. The importance of spectral information in the UV range is emphasized again. Colour plays a critical role in the comparison of cotton fibres in forensic sciences. Normally, fibres producing spectral patterns that are frequently seen will tend to have a lower evidential value in criminal cases as the choice of putative sources is theoretically greater and vice versa. Besides black cotton, blue and red cotton fibres are very frequent in fibre casework. The very high discriminating power using a combination of light microscopy, fluorescence microscopy and UV/VIS microspectrophotometry shows that even blue and red cotton fibres can provide excellent evidence when involved in fibre transfer cases.     

Vapor-phase staining of cyanoacrylate-fumed latent fingerprints using p-dimethylaminobenzaldehyde

Contrasting or enhancing of cyanoacrylate ester-fumed latent fingerprints deposited on solvent-sensitive materials such as oil marker writings and rough surface materials such as unglazed earthenware is not easy by conventional dye solutions dipping or dye powder dusting. In this study, a new vapor-phase staining method using p-dimethylaminobenzaldehyde (DMAB) is proposed for staining such materials. DMAB has high volatility and selective absorbability to cyanoacrylate-fumed fingerprints, so that cyanoacrylate-treated samples can be easily stained by leaving them simply in a closed container along with DMAB crystals for 48-96 h at room temperature or in conjunction with the use of mild heating. The stained fingerprint could be excited by UV irradiation (365 nm), and the fluorescent fingerprint was photographed through a UV cut-off filter (420 nm). The new method achieved minimally destructive fluorescent staining for the solvent-sensitive samples and the rough surfaced samples.     

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.     

Ultraviolet 365 as an Alternative Light Source for Detection of Blood Serum

The use of alternative light sources (ALS) in bloodstain analysis has focused on dried (whole) blood, while information on detection of blood serum is lacking. Serum detection by ALS could provide valuable information at a crime scene, as serum may become separated from blood during clotting and cast off, especially in cases where the victim is moved. Additionally, a perpetrator may concentrate on the removal/scouring of dried blood with small amounts of serum going unnoticed, as it dries relatively clear on certain objects. In this report, the detection of human blood serum was evaluated using ultraviolet (UV) light at two different wavelengths. These results show that ultraviolet (UV) at 365 nm (UV365) was effective in the detection of even small amounts of blood plasma and serum, compared with UV at 395 nm, which was not. UV365 was also found to be useful in distinguishing blood imprints from clotting blood which had been transferred to material versus blood that had been added directly. Taken together, these results demonstrate that UV365 may be utilized as a simple, nondestructive method for blood serum detection.     

Exploiting expressed sequence tag databases for the development and characterization of gene-derived simple sequence repeat markers in the opium poppy (Papaver somniferum L.) for forensic applications

Simple sequence repeat (SSR) markers in the opium poppy (Papaver somniferum L.) were identified from an expressed sequence tag (EST) database comprised of 20,340 sequences. In total, 2780 SSR-containing sequences were identified. The most frequent microsatellite had an AT/TA motif (37%). Twenty-two opium poppy EST-SSR markers were presently developed and polymorphisms of six markers (psom 2, 4, 12, 13, 17, and 22) were utilized in 135 individuals under narcotic control investigation. An average of three alleles per locus (range: 2-5 alleles) with a mean heterozygosity of 0.167 was detected. Six loci identified 29 unique profiles in 135 individuals. The EST-SSR markers exhibited small degrees of genetic differentiation (fixation index = 0.727, p < 0.001). Other variable markers will be needed to facilitate the forensic identification of the opium poppy for future cases. To determine the potential for cross-species amplification, six markers were tested in five Papaver genera species and two Eschscholzia genera. The psom 4 and psom 17 primer pair was transferable. This is the first study to report SSR markers of the opium poppy.     

A further study of dye batch variation in textile and carpet fibres.

Four sets of acrylic fibre samples were obtained from a company that dyes fabrics for the fashion industry. Between seven and ten different batches of fibres constituted each set. Comparison microscopy, visible and UV range microspectrophotometry and thin layer chromatography (TLC) were used to compare the dyes on each batch of fibres within the sets. Only one of the four sets exhibited variation within the batches. The differences were seen when both microscopical and analytical techniques were used. In addition, two further sets of samples had been obtained from a company that produces carpets for the car industry. The first set consisted of 26 batches of acid dyed orange nylon fibres. The second consisted of 21 batches of acid dyed mustard coloured nylon and direct dyed brown viscose fibres blended together. When the first set was viewed under UV light one batch had more pale orange fibres present and they fluoresced more brightly than the other fibres. This could be due to the blending with a different dye batch of fibre or due to poor dye uptake--the latter being more likely. When tested using visible and UV range microspectrophotometry and TLC, further dye batch variation was not detected. The second set was examined after separating the nylon and viscose fibres from each other. The nylon fibres were indistinguishable when a range of microscopical and analytical techniques were employed; however, the viscose fibres showed dye batch variation when TLC was used.     

Visualization and LC/MS analysis of colorless pepper sprays

Pepper sprays are used in a variety of circumstances, including criminal activity, self-defense, and law enforcement. As such, the presence or absence of pepper sprays on evidentiary materials is often important when determining the facts of an incident. When no visible stains are present on evidentiary materials, ascertaining the presence or absence of pepper spray can be a challenge to the forensic analyst. A method, based on a chemical derivatization of capsaicinoids using a diazonium salt, has been developed for the visualization of colorless, ultraviolet (UV) activated fluorescent dye-free pepper sprays on textiles. Identification of both the capsaicinoids and their derivatives is confirmed via extraction of the derivatized capsaicinoids followed by liquid chromatography/mass spectrometry (LC/MS) analysis. LC/MS analysis is conducted using a YMC Basic column and elution of the compounds using a gradient of 10 mM ammonium formate, pH 4.2 and methanol at 0.35 mL/min. Full-scan MS data are collected for the full 6.5 min LC analysis. Although this method is qualitative in nature, visual detection of as little as 50 microL of a 0.2% pepper spray (equivalent to approximately 0.1 mg) on a variety of garments is possible, and more than adequate signal-to-noise is obtained for reconstructed ion chromatograms on LC/MS analysis at these levels.