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.     

Preliminary Study on Determining the Sequence of Intersecting Lines by Fluorescence Technique

The determination of the sequence of intersecting lines is an important part of questioned document examinations. A fluorescence technique was used to determine the sequence of heterogeneous intersecting lines produced using inkpad ink, stamp‐pad ink, ballpoint pens, gel pens, fountain pens, colorants of carbon paper, photocopiers, laser printers, and inkjet printers. A SteREO Discovery.V20 equipped with the ZEN Blue Lite software was chosen to perform the tests.As the results obtained from the study were positive under most conditions, the fluorescence technique was found to be very successful in determining the sequence of intersecting lines from ballpoint pen, gel pen, fountain pen, photocopier, laser and inkjet printers, and inkpad inks. The method was also successful in determining the sequence of intersecting lines from ballpoint pen, photocopier, laser printer, and stamp‐pad inks under most conditions. The technique was not successful in determining the order of crossing lines blending together.     

A study to investigate the evidential value of blue and black ballpoint pen inks in Australia

The aim of this project was to investigate the evidential value of blue and black ballpoint pen inks in Australia. For this purpose, 49 blue and 42 black ballpoint pen inks, of different brands, models and batches, representative of those ballpoint pens available on the Australian market at the time of the study, were analysed by three techniques: filtered light examination (FLE); reflectance visible microspectrophotometry (MSP); and thin-layer chromatography (TLC). The results showed that the power of the individual techniques to discriminate inks between and within brands, models and batches varied, the most informative techniques being TLC>FLE>MSP. The greatest degree of differentiation was achieved when using a combined sequence of techniques, the discriminating power being 0.99 and close to 1 for blue and black inks, respectively (different brands and models). In respect to the discrimination between different batches of a same brand and model, it was shown that 14 out of the 33 pairs compared could be discriminated. Overall, this study confirmed the high value of the examination of inks when applied to ballpoint pens available in Australia, especially when a combined sequence of techniques is applied.     

Quantitative evaluation of europium in blue ballpoint pen inks/offset printing inks tagged with europium thenoyltrifluoroacetonate by spectrofluorometry and ICP-AES

Tagging of writing/printing inks with suitable inorganic taggants such as rare-earth chelates has the potential to help document examiners identify fraud in sensitive written/printed documents. Selection of rare-earth chelates as taggants primarily depends on the satisfactory sensitivity of analytical determination and the absence of the taggants in normal varieties of inks used for document writing/printing. Spectrofluorometric determination of trace amounts of europium in blue ballpoint pen inks and offset printing inks tagged with europium thenoyltrifluoroacetonate was carried out with sodium tungstate solution. Sodium tungstate acts as a specific reagent that enhances the fluorescence intensity of the Eu3+ ion. The excitation and emission wavelengths are 270 nm and 605 nm respectively. The results were compared with the data obtained with ICP-AES. Satisfactory recoveries were observed with precision better than 5% RSD and comparable accuracy. Under the optimized experimental conditions, detection limits and quantitation limits were determined. The detection limits obtained by spectrofluorometry and ICP-AES were 0.01 microg/mL and 0.006 microg/mL respectively whereas the limits of quantitation were about 0.03 microg/mL and 0.018 microg/mL respectively. The spectrofluorometric method is rapid, selective, sensitive and accurate for the determination of europium in blue ballpoint pen ink and offset printing inks and may be suitable for application in the examination of sensitive documents to aid in document related crime investigation. The advantages and limitations of the tagging approach and proposed analytical techniques are discussed.     

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。     

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.     

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”.     

Application of Raman spectroscopy in forensic investigation of questioned documents involving stamp inks

Stamp pad inks from different manufacturers across India have been analyzed to investigate the feasibility of Raman scattering as a tool for forensic analysis of questioned documents involving stamp inks. Nine different stamping inks were analyzed by both Raman spectroscopic and HPTLC methods. The results demonstrate the effectiveness of these methods in classifying the investigated stamping inks based on their spectral pattern and HPTLC chromatogram. Raman scattering tool was able to determine the sequence of heterogeneous intersection strokes involving a blue stamp pad ink and other writing instruments, such as ballpoint pen ink (red and black), pencil and laser printer toner. However, this method was unable to resolve the exact sequencing for the intersection strokes involving investigated stamp ink and blue ballpoint ink or gel pen ink (all colors).     

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.     

Dynamic of the ageing of ballpoint pen inks: quantification of phenoxyethanol by GC-MS.

The ageing process of some inks were studied to evaluate whether it is possible to date them. We used gas chromatography coupled with mass spectrometry to measure the evaporation of volatile components. The selected approach thus follows the disappearance of one ink volatile component (phenoxyethanol) as a function of time. The ink ageing curve represents the ratio of an evaporating compound to a stable compound of ink according to time. The results obtained are thus independent of the quantity of ink sampled for analysis. We obtained for two pens, containing two different inks, a curve highlighting an exponential decrease of the evaporating compound. By fitting these curves we determined the limitations of dating a ballpoint pen ink. Two distinct behaviours were observed in two distinct modes, the first called 'fast mode' and the second called 'slow mode'. In order to try to explain the phenomenon, the studies were based on solvent diffusion theory in complex matrix (such as polymer on varnish). Calculations from certain parameters showed an extremely fast evaporation of ink solvents, as well as varying behaviour depending on the paper used. The results showed that it is not possible to date ballpoint pen inks with this method in document examination casework.     

Application of Micro‐Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy to Ink Examination in Signatures Written with Ballpoint Pen on Questioned Documents

Questioned documents examined in a forensic laboratory sometimes contain signatures written with ballpoint pen inks; these signatures were examined to assess the feasibility of micro‐attenuated total reflectance (ATR) Fourier transform infrared (FTIR) spectroscopy as a forensic tool. Micro‐ATR FTIR spectra for signatures written with 63 ballpoint pens available commercially in Korea were obtained and used to construct an FTIR spectral database. A library‐searching program was utilized to identify the manufacturer, blend, and model of each black ballpoint pen ink based upon their FTIR peak intensities, positions, and patterns in the spectral database. This FTIR technique was also successfully used in determining the sequence of homogeneous line intersections from the crossing lines of two ballpoint pen signatures. We have demonstrated with a set of sample documents that micro‐ATR FTIR is a viable nondestructive analytical method that can be used to identify the origin of the ballpoint pen ink used to mark signatures.     

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.     

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.     

Systematic analysis of bulk blue ballpoint pen ink by FTIR spectrometry

A classifying method on bulk blue ballpoint pen ink has been studied by Fourier transform infrared (FTIR) spectroscopy. By using this method, a total of 108 blue ink samples have been divided into two groups depending on their main component. Spectral characteristics of these inks such as frequency and absorbance are described by way of artificial intelligence of pattern recognition, and 35 subgroups from the 108 inks are distinguished by their correlation coefficient (lambda). Under heat or exposure to ultraviolet light a mode of change in the age of the inks has been obtained. This approach has provided a reliable and nondestructive method for the characterization of bulk ballpoint writing ink, and more importantly, it might be a basis for dating of the blue ballpoint pen ink.     

Application of the micro-FTIR spectroscopy, Raman spectroscopy and XRF method examination of inks

In routine examination of inks on questioned documents non-destructive analytical methods, such as microscopic and optical techniques are applied first. However, they are often insufficient to identify the inks used for the preparation of the document. In such cases, it is necessary to apply chemical methods that normally cause partial destruction of the examined material. The aim of this work was to evaluate the possibility of discrimination between inks by the use of spectrometric methods, i.e. micro-FTIR spectroscopy, Raman spectroscopy and XRF. About 70 samples of blue and black ballpoint pen and gel inks were examined. It was found that about 90% of the samples of the same type and colour could be distinguished using these methods.     

紫外-可见光谱法研究蓝色圆珠笔色痕自然老化规律

目的论述自然老化下蓝色圆珠笔色痕中染料成分的变化规律。方法利用UV-VIS光谱对圆珠笔文字色痕中染料成分相对于铜酞菁的变化进行实验。结果得到染料与铜酞菁吸光度之比随老化时间变化的数据和曲线。结论利用UV-Vis光谱研究文件制成时间是可行的,为书写时间的鉴定拓展了思路。     

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.     

Changes in composition of ballpoint pen inks on aging in darkness

A method for comparison of the relative age of ink entries written by the same ballpoint pen on documents stored in darkness is presented. Inks were extracted from the document and analyzed by HPLC (high performance liquid chromatography). On aging, changes in the chemical composition of the inks were noted. These changes were similar to those observed when inks were exposed to light or heat. The aging was followed by using ternary diagrams constructed for dyes generally present in blue-colored inks--Crystal Violet, Methyl Violet, and Tetramethyl Para Rosaniline. The procedure is applicable for relative dating of ink entries in diaries, notebooks, etc., where often several ink entries are written by the same ink. However, a prolonged exposure of the document to daylight and/or artificial light (light from fluorescent tubes) as well as to extensive heat will render the whole procedure inapplicable. An example of the use of the proposed method in casework is given.     

An examination of the sequence of intersecting lines using attenuated total reflectance-Fourier transform infrared spectral imaging

In this study, the potential of attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectral imaging as a technique to determine the sequence of line crossings was examined. The technique was successful in determining the sequence of heterogeneous line intersections produced using ballpoint pens and laser printers. By imaging at characteristic frequencies, it was possible to form spectral images showing the spatial distribution of the materials. By examining the spectral images from the inks, it was possible to determine whether the ink was above or below the toner. In blind testing, ATR-FTIR spectral imaging results were directly compared to those obtained by eight experienced forensic document examiners using methods regularly employed in casework. ATR-FTIR spectral imaging was shown to achieve a 100% success rate in the blind tests, whereas some incorrect sequence determinations were made by the forensic document examiners when using traditional techniques. The technique was unable to image ink-jet printing, gel pens, roller ball pens, and felt-tip pens, and was also unable to determine the sequence of intersecting ballpoint pen lines.     

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。