应用HPLC研究蓝色签字笔迹字迹色痕光老化规律

目的对蓝色签字笔所形成的字迹色痕光老化规律进行研究。方法比对14种蓝色签字笔样品在暗处保存条件下、自然光照射及强灯光照射等老化条件下物理特征变化情况;使用高效液相色谱法,监测蓝色签字笔墨水中色料成分的变化情况,并寻找蓝色签字笔墨水字迹自然光老化规律。结果强灯光照射后出现外观明显的老化现象,暗处存放的样本存在较长的老化时限。在自然光照射下30天内,样品色料成分的相对含量均随时间发生两个阶段的变化。结论样本字迹的外观为鉴定蓝色签字笔墨水字迹的形成时间提供了重要的信息。结合HPLC分析结果,可以确认字迹是否经过光照人工老化,为字迹形成时间鉴定的重要参考依据。     

基于银胶表面增强拉曼光谱检验蓝色书写字迹初探

目的用基于银胶的表面增强拉曼光谱技术检验蓝色签字笔字迹。方法取4种常见不同牌号的蓝色签字笔在其字迹上滴加微量银胶,用显微共焦拉曼光谱仪进行检验。结果不同品牌的蓝色签字笔字迹的表面增强拉曼光谱不同。结论基于银胶的表面增强拉曼光谱技术可用于纸张上蓝色签字笔字迹的检验。     

光谱成像检验同种同色涂抹掩盖字迹研究

目的建立一种无损、灵敏、直观的同种同色涂抹掩盖字迹的显现方法。方法依据涂抹掩盖字迹油墨物质的同色异谱特征,利用可见光滤波型多光谱成像检验系统进行检验。结果黑色圆珠笔、蓝色圆珠笔、黑色签字笔和蓝色签字笔相互涂抹掩盖形成的同种同色涂抹掩盖样本,利用可见光滤波型多光谱成像检验系统进行检验,显效率分别为90.5%、69.1%、49.5%、78.6%,显现效果良好。结论多光谱成像技术可以显现同种同色涂抹掩盖字迹,且具有良好的显现效果。     

透射光谱成像技术检验黑色签字笔涂抹掩盖字迹研究

目的 对透射光谱成像技术和反射光谱成像技术检验黑色签字笔间涂抹掩盖字迹进行比较研究,探寻一种无损、高效、直观的黑色签字笔涂抹掩盖字迹的显现方法,提高黑色签字笔间涂抹掩盖字迹显现效率。方法根据不同黑色签字笔油墨物质成分不同,不同物质对光的透射率各异的特征,在相同条件下使用反射光谱成像技术与透射光谱成像技术分别对多个黑色签字笔间涂抹掩盖字迹实验样本进行检验。本文将显现效果分为可显现和不可显现两类。分类标准为从未看过原字迹的非文检人员是否可以辨认出被涂抹掩盖字迹。结果 利用透射光谱成像检验系统检验黑色签字笔涂抹掩盖字迹样本,306个样本中,可显现的有231个,不可显现的75个,显效率为75.49%;反射光谱成像技术检验306个样本,其中可显现的有159个,不可显现的有147个,显现效率为51.96%。实验结果表明透射光谱成像检验黑色签字笔涂抹掩盖字迹的显现率高于反射光谱成像检验的检验。结论 除了无法显现原字迹与涂抹掩盖笔迹的油墨物质成分、浓度以及组成配比相同或相近的样本之外,透射光谱成像技术能检验常规的光谱成像技术无法显现的黑色签字笔间涂抹掩盖字迹,其显现效果和效率都优于反射光谱成像技术,是一种高效的显现方法 ,可以应用于刑事物证检验领域。     

拉曼光谱成像技术检验朱墨时序中书写笔种类对检验结果的影响研究

目的考察在运用拉曼光谱阵列面扫描检验朱墨时序的方法中书写笔油墨种类对检验结果的影响。方法根据拉曼谱图的不同对搜集的188种书写笔（包括22种黑色圆珠笔,62种蓝色圆珠笔,62种黑色签字笔,42种蓝色签字笔）进行扫描并分类,采用拉曼光谱阵列面扫描技术对书写笔与同一印泥和印油形成的朱墨时序样本进行检验。结果 188种书写笔被分为4大类23小类,4类书写笔与印泥或印油形成的朱墨时序样本都得到了较好的检验结果。结论在本实验条件下,书写笔油墨种类对拉曼光谱阵列面扫描检验朱墨时序的检验结果没有影响。     

签字笔墨水字迹形成时间研究综述

字迹色痕形成时间检验是法庭科学领域的热点和难点问题之一.签字笔现在已成为最常用的书写工具,签字笔墨水字迹形成时间鉴定成为字迹色痕形成时间鉴定技术的一个重要组成部分.文章对国内有关签字笔墨水字迹形成时间鉴定的文献进行了综述,介绍了用于形成时间鉴定的无损检验和有损检验方法,对各种方法的适用性和检验条件进行了简单的分析总结,以期对相关研究人员提供借鉴作用,并在各类案件的侦查、诉讼和审判中发挥作用.     

拉曼光谱成像技术检验朱文时序时印文油墨种类对检验结果的影响

目的考察在运用拉曼光谱阵列面扫描检验朱文时序的方法中印文油墨种类对检验结果的影响。方法根据拉曼谱图的不同对搜集的21种印泥印油进行扫描并分类,采用拉曼光谱阵列面扫描技术对印泥印油与同一书写笔形成的朱文时序样本进行检验。结果 21种印泥印油被分为11类,21种印泥印油与蓝色签字笔形成的朱文时序样本都得到了良好的检验结果。结论印文油墨种类用拉曼光谱阵列面扫描检验朱文时序的检验结果没有影响。     

中性墨水笔墨迹中甘油成分的气相色谱分析及历时性变化初探

目的对中性墨水笔墨迹中甘油成分和随时间变化规律进行研究。方法利用气相色谱法分析了含有甘油溶剂成分的中性墨水笔字迹墨迹,并对甘油成分含量相差较大的字迹样本的变化规律进行了研究。结果得到了3种字迹墨迹中甘油成分随字迹形成时间变化的关系曲线。结论曲线变化规律表明,书写时间6个月的中性墨水笔墨迹中甘油成分的含量变化出现拐点,6个月以后甘油成分的含量基本趋于不变。     

蓝色圆珠笔字迹色痕FT-IR光谱经时变化的研究

笔者曾用FT-IR光谱法对108种不同蓝色圆珠笔油墨进行了系统分析,确定了油墨组成成份,实现了种类认定.在此基础上,选取了二种不同种类的蓝色圆珠笔油墨字迹色痕,在紫外光下定时照射,根据各自光谱特征峰校正峰高的计算,确定相关峰的相对峰高比.根据相对峰高比值随时间变化的规律,进行了曲线拟合和计算机编程.同时,探讨了油墨组份之间随光照时间的变化,其目的是为了推断字迹色痕的“年龄”.     

文检仪显现同种同色掩盖字迹条件的初探

目的研究运用文检仪显现同种同色掩盖字迹的显出条件。方法以黑色签字笔为例,依据不同型号笔的油墨在不同光源下的荧光性质和红外吸收能力的差异,利用文检仪进行分析检验。结果只有在一定条件下被掩盖字迹才能被显出。结论在LUMI=IR红外荧光（兰光）下,只能显现激发荧光的油墨掩盖不能激发荧光的油墨的字迹和激发荧光能力弱的油墨掩盖激发荧光能力强的油墨的字迹;在红外吸收光和365nm长波紫外表面光下,只能显现颜色浅的油墨掩盖颜色深的油墨的字迹。     

书写材料的无损检验系统研究

本研究运用显微分光光度仪、文件检验仪和傅立叶变换拉曼光谱仪三种方法,分别对在中国市场上收集的不同厂家、牌号、型号的35种黑墨水、20种蓝黑墨水、22种蓝墨水、49种黑色墨水笔、30种蓝色墨水笔、45种黑色圆珠笔、和50种蓝色圆珠笔等七组样品进行非破坏检验。结果表明:(1三种非破坏检验方法都能单独对七组样品进行不同程度的鉴别,区分率在50%—94.4%之间;(2)三种方法联用后对黑墨水、蓝黑墨水、蓝墨水、黑色墨水笔、蓝色墨水笔、黑色圆珠笔和蓝色圆珠笔的区分率可分别提高到93.4%、97.3%、99.1%97.2%、97.2%、95.6%和91.8%。通过三种非破坏检验方法的联用,证明它们之间有较强的互补性,最大限度地提高了检验效应,可建立系统的非破坏检验方法。     

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.     

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.     

A statistical methodology for the comparison of blue gel pen inks analyzed by laser desorption/ionization mass spectrometry

A statistical methodology for the objective comparison of LDI-MS mass spectra of blue gel pen inks was evaluated. Thirty-three blue gel pen inks previously studied by RAMAN were analyzed directly on the paper using both positive and negative mode. The obtained mass spectra were first compared using relative areas of selected peaks using the Pearson correlation coefficient and the Euclidean distance. Intra-variability among results from one ink and inter-variability between results from different inks were compared in order to choose a differentiation threshold minimizing the rate of false negative (i.e. avoiding false differentiation of the inks). This yielded a discriminating power of up to 77% for analysis made in the negative mode. The whole mass spectra were then compared using the same methodology, allowing for a better DP in the negative mode of 92% using the Pearson correlation on standardized data. The positive mode results generally yielded a lower differential power (DP) than the negative mode due to a higher intra-variability compared to the inter-variability in the mass spectra of the ink samples.     

墨水书写时间测定的进展

本文追述了从20世纪20年代初到90年代末书写墨水的时间测定的进展.这包括,介绍新检验方法建立所需遵循的基本要求;推荐目前案件检验的工作程序,即墨水种类的确定,可疑文件的外观检验,同牌号、同配方、同批号比对样本的寻找;评述目前已为办案使用的各种书写年代测定的方法,如扩散法,转印法,染料比值法,气相色谱法、溶剂萃取法,差示扫描量热法等;以及讨论了有望用于年代测定的一些新技术,如用于钢笔墨水的电化学法,光谱法和用于圆珠笔墨水的显微分光光度法,付里叶变换拉曼光谱法等.     

A study to investigate the evidential value of blue gel pen inks

The aim of this project was to investigate the evidential value of blue gel pen inks in Europe. For this purpose, 33 blue gel pen inks, of different brands and models, representative of those available on the European market at the time of the study, were analyzed using three techniques: filtered light examination (FLE), Raman Spectroscopy (RS), and scanning electron microscopy (SEM). First, after visual examination (naked eye and stereo microscope), it was possible to classify the 33 inks into three groups described as: milky, metallic, and normal. This paper describes in detail the results obtained for the normal gel pen group. The ability of the techniques to discriminate gel inks between and within brands varied. The results indicated that RS and SEM were more discriminating than FLE. The greatest degree of differentiation was achieved when using a combination of RS and SEM techniques (discriminating power = 0.91). This study also highlights some problems concerning the identification of the brand of a gel pen from a written text.     

Identification of colorants in pigmented pen inks by laser desorption mass spectrometry

Pigments are rapidly replacing dyes as colorants in pen and printer inks, due to their superior colors and stability. Unfortunately, tools commonly used in questioned document examination for analyzing pen inks, such as TLC, cannot be used for the analysis of insoluble pigments on paper. Laser desorption mass spectrometry is demonstrated here as a tool for analyzing pigment-based pen inks. A pulsed nitrogen laser can be focused onto a pen stroke from a pigmented ink pen on paper, and positive and negative ions representative of the pigment can be generated for subsequent mass spectrometric analysis. Targeted pens for this work were a set of Uni-ball 207 pigmented ink pens containing blue, light blue, orange, green, violet, red, pink, and black inks. Copper phthalocyanine was identified as the pigment used to make both blue inks. A mixture of halogenated copper phthalocyanines were identified in the green ink. Unexpectedly, the pink ink was found to contain a red pigment, Pigment Red 12, treated with a mixture of water-soluble dyes. Each sample yielded ions representative of the pigments present.     

Evaluation of principal components analysis with high-performance liquid chromatography and photodiode array detection for the forensic differentiation of ballpoint pen inks.

Inks from seven black and eight blue ballpoint pens were separated by a high-performance liquid chromatography (HPLC) method utilizing a photodiode array detection (PDA). A classifier flowchart was designed for the chromatographic data based on the presence or absence of certain peaks at different wavelengths to qualitatively discriminate between the inks. The same data were quantitatively classified by principal components analysis (PCA) to estimate the separation between a pair of classes of ink samples. It was found that the black ballpoint pen inks were discriminated satisfactorily utilizing two-dimensional data of the peak areas and retention times at the optimum wavelengths. The blue pens were discriminated by analyzing the chromatographic data at four different wavelengths simultaneously with a cross-validated PCA. The results of this study indicated that HPLC-PDA coupled with chemometrics could make a powerful discriminating tool for the forensic chemist, especially when analyzing extensive and/or complex data.     

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.     

Classification and individualization of black ballpoint pen inks using principal component analysis of UV-vis absorption spectra

The technique of principal component analysis has been applied to the UV-vis spectra of inks obtained from a wide range of black ballpoint pens available in the UK market. Both the pen ink and material extracted from the ink line on paper have been examined. Here, principal component analysis characterised each spectrum within a group through the numerical loadings attached to the first few principal components. Analysis of the spectra from multiple measurements on the same brand of pen showed excellent reproducibility and clear discrimination between inks that was supported by statistical analysis. Indeed it was possible to discriminate between the pen ink and the ink line from all brands examined in this way, suggesting that the solvent extraction process may have an influence on these results. For the complete set of 25 pens, interpretation of the loadings for the first few principal components showed that both the pen inks and the extracted ink lines may be classified in an objective manner and in agreement with the results of parallel thin layer chromatography studies. Within each class almost all inks could be individualised. Further work has shown that principal component analysis may be used to identify a particular ink from a database of reference UV-vis spectra and a strategy for developing this approach is suggested.