Differentiation between inks of the same brand by infrared luminescence photography of their thin-layer chromatograms

A case is reported involving a U.S. Treasury check with an altered amount payable. The ink in the alteration and the ink in the endorsement signature were compared with ink from three Skilcraft ball pens all having Skilcraft black ink ball pen refills. Infrared luminescence photography of their thin-layer chromatograms revealed differences between the inks in the three pens.     

签字笔水、圆珠笔油红外发光特性的研究

目的记录不同激发光、接收滤光镜下,各种油墨红外发光强弱的程度,为文字检验提供基础性的研究。方法用多波段光源中510~650nm单色光激发各种油墨样本,全波段物证检验CCD系统记录样本在530~950nm接收滤光镜下出现的红外发光图像。结果多数油墨在接收滤光镜到达800~850nm时,呈现出强烈的红外发光状态,并随接收波段的上升而开始衰减。结论可利用某些油墨的发光与否,发光强与弱的特性,检验案件中涂改和涂抹字迹。     

Forensic discrimination of blue ballpoint pen inks based on thin layer chromatography and image analysis

This article aims to provide a new and fast method for differentiation of inks on a questioned document. The data acquisition was carried out by designing specific image analysis software for evaluating thin layer chromatograms (TLC-IA). The ink spot was extracted from the document using methanol and separated by TLC using plastic sheet silica gel 60 without fluorescent indicator, and a mixture of ethyl acetate, ethanol, and water (70:35:30, v/v/v) as mobile phase. To discriminate between different pen inks, new software was designed on the basis of intensity profile of red, green, and blue (RGB) characteristic. In practice, after development of chromatogram, the chromatograms were scanned by ordinary office scanner, intensity profiles of RGB characteristics on the development straight of each sample were produced and compared with the mentioned software. RGB profiles of ballpoint inks from various manufacturers showed that the patterns in most cases were distinctly different from each other. This new method allowed discriminating among different pen inks with a high reliability and the discriminating power of 92.8%. Blue ballpoint pen inks of 41 different samples available on the local market were successfully analyzed and discriminated.     

The use of filtered light for the evaluation of writing inks analyzed using thin layer chromatography

Thin layer chromatography (TLC) is a scientific methodology that can be used to compare and characterize ink formulations. Occasionally, when evaluating chromatographic profiles on a TLC plate with ambient light, different ink formulations, or the same inks from different batches, may appear indistinguishable. The use of filtered light can be very effective to illuminate characteristics that are not readily apparent with ambient light. There are a diverse number of components commonly found in writing inks, and it may be that some of them respond to particular wavelengths of energy that are not visible to the unaided eye (i.e., colorless). There has been very little information published that addresses the use of filtered light for evaluating TLC plates. Twenty-nine ballpoint writing ink samples were selected for TLC analysis. Further evaluation using an alternate light source, coupled with the appropriate filter, proved to be an effective means for definitive discrimination in some cases.     

Differentiation of coloured inks of inkjet printer cartridges by thin layer chromatography and high performance liquid chromatography

Document examiners are frequently asked to determine whether or not a colour printout has originated from a particular inkjet printer. The printer can rarely be identified unless some unique defects or irregularities of the printer are present on the printout. However, it is possible to decipher the make and/or model of the printer by comparing the ink-profile of the questioned printout with that of a seized inkjet printer cartridge or from one in a database. This paper presents an overview of a systematic approach to characterising and discriminating the inks of different inkjet printer cartridges using thin layer chromatography (TLC) and high pressure liquid chromatography (HPLC) with multi-wavelength ultra-violet/visible (UV/Vis) detection. Ink samples from 23 different inkjet printer cartridges (including originals and substitutes) of different brands and colour printouts, printed by known printers were examined with newly developed chromatographic methods. Subsequently, a database of the ink-profiles was generated. The methods provide a useful tool for discriminating coloured inks in inkjet printer cartridges of different brands.     

The discrimination potential of ultraviolet-visible spectrophotometry, thin layer chromatography, and Fourier transform infrared spectroscopy for the forensic analysis of black and blue ballpoint inks

The knowledge of the discriminating power of analytical techniques used for the differentiation of writing inks can be useful when interpreting results. Ultraviolet-visible (UV-VIS) spectrophotometry, thin layer chromatography (TLC), and diffuse reflectance Fourier transform infrared spectroscopy (FT-IR) were used to examine a population of 21 black and 12 blue ballpoint writing inks. Based on corroborative results of these methods, the discrimination power for UV-VIS, TLC, and FT-IR was determined to be 100% and 98% for the black and blue inks, respectively. Generally, TLC and UV-VIS can be used to differentiate the colorant components (i.e., dyes and some pigments) found in inks. As FT-IR can be utilized to identify some of the noncolorant components, it was determined to be an excellent complementary technique that can be implemented into an analytical scheme for ink analysis.     

薄层色谱法检测丁丙诺啡

目的建立丁丙诺啡薄层色谱分析方法。方法血浆先用乙醇除蛋白,尿、水剂样品则直接加pH10.8Na2CO3/NaHCO3缓冲溶液后用氯仿提取,提取液经净化浓缩后进行薄层色谱分析。结果选定碘化铋钾作显色剂,丁丙诺啡薄层色谱分析展开效果较好,检测灵敏度为0.5μg,血浆、尿液和水剂中检出限分别为0.7、0.7和0.6μg/ml。结论该方法适用于涉毒案件中丁丙诺啡的日常检验。     

A comparison of the use of visible microspectrometry and high performance thin layer chromatography for the discrimination of aqueous inks used in porous tip and roller ball pens

Ink lines made by porous tip and roller ball pens have been examined by high performance thin layer chromatography (HPTLC) and by transmission microspectrophotometry (VM) in the visible region. Better discrimination between apparently similar coloured inks was obtained with HPTLC but VM has value as an additional technique for ink examination.     

圆珠笔油墨字迹书写时间鉴别的研究

圆珠笔油墨字迹书写时间的鉴别是摆在文件鉴定人员面前的棘手问题.本文作者借鉴国外的检验方法,经过近十年的探索,考查了各种因素的影响,研究出了适合我国国情的通过圆珠笔字迹油墨被溶解能力测试来确定其书写时间的鉴定技术,并且进一步发展了国外的检验方法,研制出了专用的检验器材,发明了模拟低温操作程序,使这一技术的适用范围更广.在有合适比对样本的情况下,可以准确鉴别落款时间在一年以上、怀疑书写时间在半年以内的可疑文件的真伪.     

傅立叶变换拉曼光谱法鉴别黑色墨水的研究

采用傅立叶交换拉曼光谱法对6种黑色墨水字迹进行检验分析实验结果表明,能对黑色墨水样品进行有效的鉴别。该方法具有快速、简便、不破坏样品的特点。     

Raman spectroscopy of blue gel pen inks

Raman spectroscopy is becoming a tool of major importance in forensic science. It is a non-invasive, non-destructive analytical method allowing samples to be examined without any preparation. This paper demonstrates the use of the technique as a general tool for gel pen inks analysis. For this purpose, 55 blue gel pen inks, of different brands and models representative of gel pen available on the world market at the time of this study, were collected. A preliminary solubility test in methanol allowed separating them into two classes: 19 dye-based and 36 pigment-based gel inks. The latter were analysed by Raman spectroscopy (RS) using two wavelength laser sources (514.5 and 830 nm). Two main pigments were identified, pigment blue 15 and pigment violet 23.     

Identification of haloperidol and tiapride in the urine with thin layer chromatography

How to identify haloperidol and tiapride in the urine by thin layer chromatography was proposed. Optimal systems of solvents were selected by chromatographic mobility of the substances studied in 14 solvents with different polarity. The findings allowed making an optimal choice of the composition and proportion of the solvents. Diethylamine, as a basic modifier, was introduced in the system of solvents. This improved chromatographic mobility of haloperidol and tiapride. Optimal mobile phases, developers were found, the threshold of detectability of the substances in the given conditions was established. The techniques were used for identification of haloperidol and tiapride in the samples from model urine mixture in the presence of non-identified endogenic compounds. They are characterized by rapid performance, selectivity, sensitivity and good reproducibility and can be introduced into practice of chemicotoxicological laboratories.     

高效液相色谱法鉴别蓝色签字笔墨水的种类

目的通过对签字笔字迹成分进行检验，达到对签字笔成分进行分离并对签字笔种类进行鉴定的目的。方法使用高效液相色谱法对蓝色签字笔字迹色痕中的色料成分进行分析，并依据分析结果对墨水的种类划分，同时考察了纸张的背景影响、最小用样量以及实验结果的重现性。结果22种蓝色签字笔样品均可以实现区分。结论本研究对实际应用有较大参考价值。     

The importance of thin layer chromatography and UV microspectrophotometry in the analysis of reactive dyes released from wool and cotton fibers

Samples of reactively-dyed wool and cotton were obtained from a range of dye manufacturers, dye distributors and the Forensic Science Service (FSS) Fibre Data Collection. The wool fibers were red in color and had previously been compared using comparison microscopy (CM), visible range microspectrophotometry (VS) and thin layer chromatography (TLC). The cotton fibers were blue and black in color and had not been previously compared. Red, blue and black fibers were chosen because they are often encountered in casework. The usage of reactive dyes to color fibers has increased over the last 10-15 years and these are often seen in casework. Before techniques were available that allowed reactively-dyed fibers to be compared using TLC only CM and microspectrophotometry were routinely carried out. Many laboratories, who had a microspectrophotometer, only had a visible range instrument. It was therefore important to see which techniques provide additional information, that gives greater individuality to fibers, to that obtained from CM. The color was released from the wool and cotton fibres using alkaline hydrolysis and a cellulase enzyme respectively. Many of the red wool samples were differentiated from each other using CM. More differentiation was found using VS and even more when ultraviolet range microspectrophotometry (UV) or TLC was used. Two samples could only be differentiated using TLC because CM, VS and UV failed to separate them. The black cotton samples were predominately differentiated using CM but VS allowed for further differentiation. With the samples used in this project UV and TLC failed to separate the samples further. The blue cotton samples benefited from the use of CM, VS and either UV or TLC to reduce the number of matching pairs. All techniques aided differentiation although with this set TLC and UV proved to be complementary techniques. Results demonstrate that TLC and UV both yield important information over and above that obtained from CM and VS. Although in some parts of the project TLC and UV are complementary if the concentration of the dye in the fiber is not sufficient for TLC or the scientist doesn't wish to 'destroy' the fiber UV would be of more use than TLC.     

Ballpoint pen inks: characterization by positive and negative ion-electrospray ionization mass spectrometry for the forensic examination of writing inks

A method based on profiling of dye components by electrospray ionization mass spectrometry (ESI/MS) is described for the characterization of ballpoint pen inks. The method involves benzyl alcohol (30 microL) extraction of ink from paper. The extracts of ink lines 1 and 5 mm in length are used for direct ESI/MS analysis in positive and negative modes, respectively. The instrumental analysis takes 3 min. Basic and acid dyes in the inks are detected in the positive and negative modes, respectively, with each dye yielding one or two characteristic ion peaks. The mass spectrum, which is mainly a compositional signature of the dyes in the ink, was not affected by the type of paper from which the ink was extracted, or by natural ageing of the ink on document in the absence of light. However, exposure to fluorescent illumination caused dealkylation of polyalkylated basic dyes and resulted in changes in the homologous distribution of the dyes. In this study, a total of 44 blue inks, 23 black inks, and 10 red inks have been analyzed, and the mass spectra were used to establish a searchable library. ESI/MS analysis provides a simple and fast way to compare ink specimens and in combination with on-line library search permits rapid screening of inks for forensic document investigations.