双溶剂提取法偏差范围的实验分析

目的双溶剂提取法是鉴定圆珠笔油墨字迹相对书写时间的方法之一,该方法简单有效,但在实际办案中发现,提取率的范围对数据的偏差范围有着直接影响。本文旨在通过实验分析偏差范围。方法通过对多种牌号的圆珠笔油墨新书写的字迹样本和自然老化样本进行平行实验。结果得到了不同提取率范围内的圆珠笔油墨提取率偏差范围。结论为双溶剂提取法鉴定圆珠笔油墨相对书写时间的界定提供了较为可靠的实验依据。     

定量转印技术确定圆珠笔字迹的相对书写时间

定量转印技术是将单溶剂提取法与转印技术相结合形成的方法,实验表明该方法在一定条件下可以判定圆珠笔字迹的相对书写时间.     

双溶剂提取法的优化

目的建立一种稳定的双溶剂提取圆珠笔油墨的实验体系,达到相对准确判断圆珠笔字迹书写时间的目的。方法依次用弱溶剂(氯苯)、强溶剂(N-N二甲基甲酰胺)溶解提取纸张上的圆珠笔油墨,点样在硅胶板上,薄层扫描得到吸收峰高值,而后根据吸收峰高值测算其相对提取率和标准偏差。结果找到了弱溶剂量10μl、取样量10~15片、弱溶剂溶解时间60s以及强溶剂量10μl的最佳实验条件。结论优化了双溶剂提取法,提高了该方法在检验鉴定中的准确度和可靠性。     

油性圆珠笔字迹书写时间鉴定的研究综述

本文追述了油性圆珠笔问世以来,字迹书写时间的检验发展过程;总结了静态法,如标准样品比对法和基准物标记法,动态法,如如溶剂萃取法、色谱法、质谱法和光谱法用于鉴定圆珠笔字迹书写时间的研究成果;展望了非破坏性方法在鉴定书写时间上的发展趋势。     

GC-HPLC法考察圆珠笔字迹油墨厚度对溶剂挥发速率的影响

目的考察圆珠笔字迹油墨厚度对溶剂挥发速率的影响。方法采用GC/HPLC联用技术对不同时间、不同字迹油墨厚度在同种纸张上的圆珠笔油墨字迹中的溶剂、染料成分的定量分析。结果字迹油墨较厚的苯甲醇、苯氧基乙醇的含量随时间的变化比字迹油墨较薄的慢。结论字迹油墨的厚度对溶剂的挥发速率影响较大。     

多次测定法确定蓝色圆珠笔字迹形成时间

通过研究相隔一定时间的多次测定数据的变化规律与书写时间的内在关系，建立了部分近期书写的圆珠笔字迹形成时间的检验方法，确定了相隔一定时间的两次测定数据的变化规律与书写时间内在关系的判定阀值。形成了无需对照样本即可判定部分圆珠笔字迹是否近期书写的检验方法。     

国产圆珠笔油墨字迹书写时间的鉴别

对国产圆珠笔油墨字迹书写时间的鉴别进行了实验研究,达到了检测速度快,实用性强,费用低的效果.     

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.     

显微激光拉曼光谱法鉴别黑色圆珠笔油墨的初步研究

利用显微激光拉曼光谱法对纸张上黑色圆珠笔油墨字迹进行检验,结果表明 ,对不同的黑色圆珠笔油墨可以有效鉴别。该方法快速、简便、不破坏样品。     

透析法测定钢笔墨水字迹的书写时间

本文通过最新研发的透析液,根据透析的原理,对书写在不同种类纸张上的不同种类的钢笔墨水字迹进行了书写时间测定。在基本保证透析液的浓度、厚度和钢笔字迹色料浓淡一致的基础上,考查了不同种类钢笔墨水字迹和不同种类纸张对透析结果的影响,得出了一般性规律,并介绍了该项新技术的原理和操作方法。     

Age determination of ballpoint pen ink by thermal desorption and gas chromatography-mass spectrometry

Two main approaches can be used for determining the age of an ink: indirect dating and direct dating. Indirect dating is based on the chemical analysis of an ink followed by comparison with known samples in a reference collection. The collection should contain information about the inks including the market introduction dates. This approach may allow for an anachronism to be detected. The second concept is based on measuring ink components that change with age. The analysis of solvents in ballpoint inks may be a useful parameter for determining the age of ink on paper. In a previous study, the authors demonstrated that thermal desorption of ink directly from paper, followed by chemical analysis using gas chromatography-mass spectrometry (GC-MS), is a promising procedure for characterizing ink-binder resins and solvents. Preliminary tests showed that monitoring the evaporation of ink solvent from ink on paper is not a suitable method for ink dating. Thermal analysis of ink on paper in two steps revealed that fresh ink releases a relative amount of solvent at a certain low temperature in a defined period of time, which decreases as the ink ages. As a consequence, this relative amount of solvent released at a certain low temperature, and its decrease with time, can be used to estimate ink age. This age-dependent parameter was studied in 85 different inks ranging in age from 1 week to 1.5 years. It was found that some inks showed a significant decrease of this parameter up to an age of several months, and that the aging process can be monitored within this period. For other inks, however, the age-dependent parameter decreases relatively fast, e.g., within a few days, to a constant level, which can be too fast for casework. Based on these results, a general procedure for assessing the age of ballpoint pen inks on paper was developed.     

Analysis of Indian blue ballpoint pen inks tagged with rare-earth thenoyltrifluoroacetonates by inductively coupled plasma-mass spectrometry and instrumental neutron activation analysis

Characterization and assessment of inks on sensitive documents for absolute/relative age determination is the challenging forensic problem in spite of practical difficulties. Tagging of ballpoint pen ink with suitable taggant(s) is a unique method to come out with definitive inferences on the detection of forgery in documents written with ballpoint pens. Selection of a proper taggant primarily depends on sensitivity of analytical determination and their absence in normal varieties of ink used for document writing. Rare-earth elements, from all technical considerations can be potential taggant(s) for inks. To ensure more compatibility with ink, 13 rare-earth thenoyltrifluoroacetonate chelates were prepared and characterized. The ballpoint pen inks were tagged with rare-earth thenoyltrifluoroacetonate chelates individually at about 1-100 ppm level depending on sensitivity of element under suitable optimized experimental conditions and instrumental sensitivity. Aliquots of such tagged ink having varying amounts of taggants were analyzed by ICP-MS and INAA. Satisfactory recoveries and a good linear relationship of intensity (signal) against concentrations/amounts were observed. Under the optimized experimental conditions, the detection limits were worked out. This study of tagging metal ions in combination with ICP-MS and NAA as an analytical tool can allow to draw various combination options based on different rare-earth chelates as suitable materials for tagging of ballpoint pen inks for absolute/relative age determination to aid in document related crime examination. The advantages and limitations of proposed analytical techniques are discussed.     

Characterization of ballpoint pen inks by thermal and desorption and gas chromatography-mass spectrometry

The characterization of ink on paper is of importance for dating and comparing questioned ink entries in forensic document examination. Inks are commonly characterized by their colorant profile that is identified by well-established analytical methods. Numerous ink formulations show identical colorant profiles, though. In order to differentiate inks that are not distinguishable by colorant analysis, a method for the characterization of colorless ink ingredients, namely binders, solvents and additives is necessary. In this paper, we propose a technique for the analysis of colorless compounds in ballpoint inks using direct thermal desorption of the ink on paper followed by chemical analysis of the desorbed volatile compounds by gas chromatography-mass spectrometry. As compared to liquid extraction and subsequent analysis of the extracts, the technique avoids possible contamination risks. Sensitivity is very high due to the enrichment of volatile components by thermal desorption. Even from old samples, the chromatograms obtained by the method enable the determination of binder polymers, solvents and additives. Pure binders as used by ink manufacturers were analyzed for unambiguous assignment of analytical results to specific polymers. To prove the practical applicability, we analyzed 121 ballpoint pens, not all having the same colorant profile, and grouped the pens into resin and solvent categories.     

The identification of 2-phenoxyethanol in ballpoint inks using gas chromatography/mass spectrometry--relevance to ink dating

Developing and implementing a generally accepted procedure for the dating of ink found on documents using dynamic approaches has been a very formidable undertaking by forensic document examiners. 2-Phenoxyethanol (PE), a common volatile organic compound found in ballpoint inks, has been recognized for over a decade as a solvent that evaporates as ink ages. More recently, investigations have focused on the solvent loss ratio of PE prior to and after heating. To determine how often PE occurs in ink formulations, the authors analyzed 633 ballpoint inks utilizing a gas chromatograph/mass spectrometer. 2-Phenoxyethanol was identified in 85% (237/279) and 83% (293/354) of black and blue inks, respectively.     

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”.     

Characterization and dating of blue ballpoint pen inks using principal component analysis of UV-Vis absorption spectra, IR spectroscopy, and HPTLC

The ink of pens and ink extracted from lines on white photocopier paper of 10 blue ballpoint pens were subjected to ultraviolet-visible (UV-Vis) spectroscopy, infrared (IR), and high-performance thin-layer liquid chromatography (HPTLC). The R(f) values and color tones of the bands separated by thin-layer chromatography (TLC) analysis used to classify the writing inks into three groups. The principal component analysis (PCA) investigates the pen responsible for a piece of writing, and how time affects spectroscopy of written ink. PCA can differentiate between pen ink and ink line indicates the influence of solvent extraction process on the results. The PCA loadings are useful in individualization of a questioned ink from a database. The PCA of ink lines extracted at different times can be used to estimate the time at which a questioned document was written. The results proved that the UV-Vis spectra are effective tool to separate blue ballpoint pen ink in most cases rather than IR and HPTLC.     

Evaluation of desorption/ionization mass spectrometric methods in the forensic applications of the analysis of inks on paper.

Fast atom bombardment and laser desorption mass spectrometry (LDMS) provide molecular level information concerning an ink's composition. Two ink-jet printer inks, Ink A containing the cationic dye Methyl Violet 2B, and Ink B containing the anionic dye, Solvent Black, were studied. Both positive and negative ion detection modes of the mass spectrometer were used. LD may be used for the analysis of inks on paper. Once on paper, the ink's solvent system has evaporated, leaving mainly the dyes behind, which are detected using LDMS. An ink fades with time, indicating that the dyes are degrading. Preliminary results from an accelerated aging study of ballpoint pen ink using UV irradiation confirm that dye degradation products are formed. The degradation chemistry follows an oxidative demethylation process for which all products formed are detected using LDMS. Results suggest that LDMS may be developed to determine the relative age of inks.