万用表测量字迹电阻方法的初步研究

目的介绍一种鉴定添加变造黑色笔迹的新方法—万用表测量字迹电阻法。方法用万用表的探针测量字迹笔画的电阻值数值,根据数值的大小范围来判断字迹是否存在添加变造。结果该方法简便快速,不破坏原件,不受检测条件及环境的限制,成本低,效率高,便于广泛推广应用。结论凡是可测出电阻值数值的,证明书写色料中的成份是以碳黑为主,凡电阻值为正无穷大时,证明书写色料中不含碳黑,而是由多种色料拼色而成的,从而可分析判断字迹是否被添加变造。     

印章色料及其色痕检验方法回顾与展望

对印章色料种类、廖分进行了简介，并对印章色料及其色痕检验方法研究的进展情况亦作了介绍，借此，还展望了对印章色料及其色痕新的检验方法。     

Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy Analysis of Red Seal Inks on Questioned Document

Seals are traditionally used in the Far East Asia to stamp an impression on a document in place of a signature. In this study, an accuser claimed that a personal contract regarding mining development rights acquired by a defendant was devolved to the accuser because the defendant stamped the devolvement contract in the presence of the accuser and a witness. The accuser further stated that the seal ink stamped on the devolvement contract was the same as that stamped on the development rights application document. To verify this, the seals used in two documents were analyzed using micro‐attenuated total reflectance Fourier transform infrared spectroscopy and infrared spectra. The findings revealed that the seals originated from different manufacturers. Thus, the accuser's claim on the existence of a devolvement contract was proved to be false.     

Could Defects on a Rubber Stamp be Reproduced on a Duplicated Rubber Stamp?

The examination of stamp impressions has been an integral part of questioned document examination since its inception. Matching in design details and unique defects has proven to be essential factors for rubber stamps and stamp impression examination. In this study, several duplicate stamps were made from various rubber stamp manufacturers in Hong Kong, from the same original stamp impression(s). The objective was to examine the stamp impressions prepared from these duplicated stamp products and compared with each other and to determine whether they could be distinguished from the source stamp impression(s); by comparison of the size and defects deliberated introduced onto the latter. Further consideration of this study was an attempt to create a perfect duplicate stamp from an original stamp impression. The results of the analysis showed that the quality of source stamp impression(s) and scanner device of the stamp manufacturing process, and the knowledge of the stamp manufacturer were critical to the quality and outcome of the duplicated stamp products. It is concluded that although a perfect duplicate stamp could only be made under several essential control conditions, it was still possible to create a duplicate stamp that replicated the features of the original when a high-quality source stamp impression was available.     

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.     

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。     

LC—MS／MS法测定蓝色圆珠笔油墨中的碱性染料

目的建立蓝色圆珠笔油墨中碱性染料的LC—MS／MS方法,为蓝色圆珠笔油墨的种类鉴别提供方法。方法用二级质谱寻找并确定结晶紫、甲基紫、维多利亚蓝B、碱性紫14、碱性蓝7和罗丹明B等碱性染料的特征性母离子／子离子对。收集50种蓝色圆珠笔．划线后对其笔道用0．5mm直径打孔器取样,乙腈超声提取。液相分离采用WatersXBridgeC18柱。流动相为0．1％甲酸缓冲液（A）-乙腈（B）,梯度程序洗脱。结果4个点的取样量足以满足检测需要,采用相对峰面积的定量方法．结果重现性好．RSD％≤2．3％。应用该方法对50种蓝色圆珠笔油墨中的碱性染料进行检测,区分率为94．4％。结论所建LC—MS／MS方法定性准确,定量可靠,为蓝色圆珠笔油墨的种类鉴别提供了方法。     

Considerations on the ASTM Standards 1789‐04 and 1422‐05 on the Forensic Examination of Ink

Abstract: The ASTM standards on Writing Ink Identification (ASTM 1789‐04) and on Writing Ink Comparison (ASTM 1422‐05) are the most up‐to‐date guidelines that have been published on the forensic analysis of ink. The aim of these documents is to cover most aspects of the forensic analysis of ink evidence, from the analysis of ink samples, the comparison of the analytical profile of these samples (with the aim to differentiate them or not), through to the interpretation of the result of the examination of these samples in a forensic context. Significant evolutions in the technology available to forensic scientists, in the quality assurance requirements brought onto them, and in the understanding of frameworks to interpret forensic evidence have been made in recent years. This article reviews the two standards in the light of these evolutions and proposes some practical improvements in terms of the standardization of the analyses, the comparison of ink samples, and the interpretation of ink examination. Some of these suggestions have already been included in a DHS funded project aimed at creating a digital ink library for the United States Secret Service.     

Differentiating writing inks using direct analysis in real time mass spectrometry

Writing ink analysis is used in establishing document authenticity and the sources and relative ages of written entries. Most analytical methods require removing samples or visibly altering the document. Nondestructive, in situ analysis of writing inks on paper without visible alteration is possible using mass spectrometry with a new ion source called Direct Analysis in Real Time. Forty-three different black and blue ballpoint, black fluid, and black gel inks were examined. Both dyes and persistent but thermally labile components of the inks contribute to the mass spectra, principally as protonated molecules [M+H](+). Numerous ink components were identified from the spectra. The spectra were placed in a searchable library, which was then challenged with two spectra from each of the 43 inks. The best match for each of the challenge spectra was correct for all but one ink, which matched with a very similar ink by the same manufacturer.