Analysis Of Inks Research Articles

Comparative Print Quality Analysis of Screen Printing and Liquid Ink Based Digital Printing Machines

Comparative Print Quality Analysis of Screen Printing and Liquid Ink Based Digital Printing Machines

Challenges Determining the Correct Deposition Order of Different Intersecting Black Inks by Time-of-Flight Secondary Ion Mass Spectrometry.

The distinction of different inks and determination of their deposition order are important forensic tasks when evaluating questioned documents. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) has received attention for these tasks due to the technique's nondestructive nature, rich mass spectral information, ability to provide chemical images, and excellent surface sensitivity. Prior literature results demonstrate the ability of ToF-SIMS to differentiate between many varieties of blue ballpoint pens and to determine the correct deposition order for selected ink intersections. The current work therefore sought to further study the intersections of different black inks. Three black pens were initially tested and were successfully distinguished. However, interesting phenomena were observed where certain inks dominated over others, causing distinctly incorrect conclusions to be made regarding ink deposition order. To explore whether these incorrect results could be corrected, different primary ions (Bi3+, Bi3+2, and Ar1000+) were used and positive and negative secondary ions were evaluated. In data analysis, restriction of the mass range was considered and different multivariate analysis techniques, principal component analysis (PCA) and multivariate curve resolution (MCR), were performed on the secondary ion images and spectra from selected regions of interest. Issues regarding incorrect apparent order of deposition persisted through the variation of all these parameters. In addition to ink differentiation, and deposition order, evidence of ink aging was also observed. These results raise several questions to be answered regarding the widespread use of ToF-SIMS for forensic ink analysis.

Elemental Analysis of Chinese Black Inks on Xuan Paper by ArF Laser-Excited Plume Fluorescence.

Chemical analysis of Chinese black ink on xuan paper is useful for the authentication of Asian artwork. The analysis has to be nondestructive and has to accommodate artworks of all sizes. We apply three analytical techniques, ArF laser-induced plume fluorescence, Fourier transform infrared (FTIR) spectroscopy, and portable X-ray fluorescence (pXRF) to analyze five commercial Chinese black inks on two kinds of xuan paper. The FTIR signal is found to be interfered by the substrate which is inevitable because the pigments diffuse extensively into the xuan fiber network. The XRF signal is shown to be feeble and no signal can be registered until the samples are stacked and when the analytes are present at tens of percent. In contrast, the plume fluorescence technique can detect the minor and trace signature elements. The method is based on a two-laser-pulse scheme performed on a high precision optical setup: the first 355 nm laser pulse ablates a thin layer of the ink to create a plume; the second 193 nm laser pulse induces multi analytes in the plume to fluoresce. Partial-least-squares discriminant analysis of the fluorescence spectra unambiguously sorts the ink-xuan combinations while the sampled area is not visibly damaged even under the microscope. The laser probe can handle samples of arbitrary size and shape, is air compatible, and no sample pretreatment is necessary.

Applications of LA–ICP–MS to Forensic Science

Laser ablation inductively coupled plasma mass spectrometry (LA–ICP–MS) provides qualitative and quantitative measurements of the elemental and isotopic composition of materials that are of interest to forensic scientists. The technique can chemically characterize physical evidence associated with a crime event, a location, contact between objects or contact between objects and a person(s). This review details the forensic application of this powerful technique for the analysis of glass, soils, ink, paper and adhesive tapes, all important evidence that benefits from trace element profiling. In addition, other applications of LA–ICP–MS for forensic purposes are referenced, including food authentication, and gold and diamond provenance.

A new CE with contactless conductivity detection method for the determination of complex cationic compositions: Application to the analysis of pen inks

A CE with contactless conductivity detection methodology using a novel background electrolyte for the separation and determination of 17 metal cations (Cs+ , Rb+ , K+ , Ca2+ , Na+ , Mg2+ , Mn2+ , Sr2+ , Li+ , Ba2+ , Fe2+ , Pb2+ , Cd2+ , Zn2+ , Co2+ , Cu2+ and Ni2+ ) and ammonium has been investigated. The buffer, based on lactic acid and β-alanine, was experimentally compared with other two commonly used electrolytes, showing important improvements, such as shorter analysis times (<11 min), better electrophoretic resolutions and higher detectabilities for certain analytes, such as Fe2+ and Pb2+ . The inclusion of other additives such as 18-Crown-6 and α-hydroxyisobutyric acid was studied in order to obtain the best separation of the analytes of interest. The optimised method was applied to the analysis of 11 water-based pen inks and the determination of their metal composition. The methodology was demonstrated for the comparison and differentiation of pen inks.

Hydrodynamic dispensing and electrical manipulation of attolitre droplets.

Dispensing and manipulation of small droplets is important in bioassays, chemical analysis and patterning of functional inks. So far, dispensing of small droplets has been achieved by squeezing the liquid out of a small orifice similar in size to the droplets. Here we report that instead of squeezing the liquid out, small droplets can also be dispensed advantageously from large orifices by draining the liquid out of a drop suspended from a nozzle. The droplet volume is adjustable from attolitre to microlitre. More importantly, the method can handle suspensions and liquids with viscosities as high as thousands mPa s markedly increasing the range of applicable liquids for controlled dispensing. Furthermore, the movement of the dispensed droplets is controllable by the direction and the strength of an electric field potentially allowing the use of the droplet for extracting analytes from small sample volume or placing a droplet onto a pre-patterned surface.

Nondestructive classification and identification of ballpoint pen inks by Raman spectroscopy for forensic document examinations

As a non-destructive analytical method, Raman spectroscopy often provides insufficient information to identify or differentiate the ink used for the preparation of a questioned document. In this study, blue and black ballpoint pen inks deposited on paper substrate were examined in situ by conventional Raman spectroscopy. Inks were successfully classified based on the total number of prominent bands in Raman spectra. It was found that more than 90% of the samples of the same type and color could be differentiated visually using only Raman spectra, i.e. 94 and 95% for blue and black inks, respectively. As a result of this study, a flow chart has been constructed for blue and black ballpoint pen inks allowing their systematic identification. Raman spectroscopy proved to be a fast and precise technique for forensic ink analysis.

Nondestructive identification of blue pen inks for documentoscopy purpose using iPhone and digital image analysis including an approach for interval confidence estimation in PLS-DA models validation

Documentoscopy is a field of forensic science that studies documents related to crime investigations. In this sense, the evaluation of pen inks used to produce these documents can help in the counterfeits identification, and the analysis of inks in paper is an important area in documentoscopy. In order to develop a methodology that allows the nondestructive accurate discrimination of pen inks types (gel, rollerball, felt tip and ballpoint pens) partial least squares for discriminant analysis (PLS-DA) was applied for the digital images obtained from an iPhone. The proposed method was tested for discrimination between 42 blue pen inks of different types and brands and validated by independent validation (or test) samples. The interval confidences estimation were considered in the validation step. Evaluations about the effect of paper characteristics and influence of the utilization of a smartphone from another brand were described. The digital images coupled with PLS-DA model can be considered robust for felt-tip pen type, since the model for this pen type did not suffer influence of the paper grammage and smartphone brand. Therefore, the proposed methodology may be considered a relevant contribution to the forensic analysis of questioned documents, since it provides a simple, fast, nondestructive and efficient way to directly analyze blue pen inks.

The effect of solvent grade on thin layer chromatographic analysis of writing inks

The effects on the separation of writing ink dyes and the repeatability of the Rf values from using different grades of chemicals used in solvent system I (SSI) and solvent system II (SSII) for thin-layer chromatographic (TLC) ink analysis were studied. Solvent system I consists of a 70:35:30 mixture of ethyl acetate, ethanol, and water. Solvent system II consists of a 50:10:15 mixture of ethanol, water, and n-butanol. Since 1991, the ASTM International Guideline E 1422 has recommended that the purity of solvents should be “reagent grade” and that water quality should be “distilled or equivalent.” A total of 25 blue and 25 black inks were selected for analysis. Thirteen of each color ink were ballpoint and the remainder were non-ballpoint. The observations show that there is a solvent grade effect on both the separation and clarity of the ink dyes and the repeatability of their Rf values. These results indicate that the grades and manufacturers of solvents used in solvent systems for thin-layer chromatography must be consistent. This is especially critical for searching TLC plates against those from a large ink library in casework. Overall, the combination of solvents that produced the best results for solvent system I consisted of denatured ethanol, HPLC grade water, and ACS grade ethyl acetate. There was no consensus for the best combination of solvent grades for solvent system II; however, it was shown that different grades did have an effect on the separation of ink components.

Spectral Imaging for Preservation Documentation

The refinement of non-invasive imaging provides new layers of scholarly and preservation data by capturing images of heritage materials in distinct wavebands of the visible and non-visible spectrum. Advancing these capabilities has allowed new interpretations of such important historical documents as those of the U.S. founding fathers documents. Image processing of large datasets generate a wealth of information, and require careful consideration of the metadata and processing to ensure no that no false imaging artifacts are produced. These imaging technologies have been expanded to gather a range of preservation information including the non-invasive characterization of colorants, and comparative ink analysis. A further advantage is the ability to undertake predictive assessment of the impact of environment and treatments. Baseline imaging allows for more data-driven decisions to be made for exhibition, and conservation treatments for stabilization.

Microstructure Analysis of Polymer Electrolyte Membrane Fuel Cell Catalyst-Ionomer Inks and Cathode Catalyst Layers By Ultra Small Angle X-Ray Scattering

The successful development of novel materials for polymer electrolyte membrane fuel cell (PEMFC) electrodes is hindered by the lack of a fundamental understanding of the complex, multicomponent nature of the catalyst layer (CL), the interplay of its components, and their independent and cooperative effects on the effective properties. One of the most prevalent methods for preparing PEMFC membrane-electrode assemblies is the thin film decal transfer (DT) method, which involves dispersing the catalyst powder and perfluorosulfonic acid ionomer in a solvent media to form a catalyst ink, and then forming a porous thin film CL which is then transferred to the membrane via hot-pressing. To achieve maximum performance, the CL needs to have (i) the maximum interface of ionomer and catalyst for the anode and cathode reactions, (ii) the appropriate pore structure to allow gas and water diffusion, and (iii) ionomer networks that bind the carbon aggregates together, providing structural integrity for the catalyst layer and a proton conduction path. For optimization, the type of solvent, solvent-to-solids ratio, and ionomer-to-carbon ratio are variables which affect the resulting CL structure and performance. Characterization of both catalyst inks and catalyst layers is necessary to understand how processing, structure, properties, and performance are all related. In this study, a systematic approach was taken to study the microstructure of the catalyst ink formulations and the prepared CLs using ultra-small-angle X-ray scattering (USAXS). By combining USAXS with small angle X-ray scattering (USAXS-pinSAXS), it is possible to obtain scattered intensity spanning over several decades in scattering vector, q (q = 4πsinθ/l), which can provide size and structural information from 1 nm to 6 mm. USAXS-pinSAXS measurements were performed at the Advanced Photon Source (APS) at Argonne National Laboratory. Multiple-level curve fitting, using a suite of macros written for Igor Pro-based software, was used to extract from the scattering data the particle size, size distribution, and geometry of the carbon-supported Pt and Pt-alloy aggregates in catalyst-ionomer-solvent inks and catalyst layers. The USAXS-pinSAXS study showed formation of aggregated microstructures, which are different for the Pt and Pt-alloy catalyst inks and catalyst layers.

TOF-SIMS Analysis of Red Color Inks of Writing and Printing Tools on Questioned Documents.

Time-of-flight secondary ion mass spectrometry (TOF-SIMS) is a well-established surface technique that provides both elemental and molecular information from several monolayers of a sample surface while also allowing depth profiling or image mapping to be performed. Static TOF-SIMS with improved performances has expanded the application of TOF-SIMS to the study of a variety of organic, polymeric, biological, archaeological, and forensic materials. In forensic investigation, the use of a minimal sample for the analysis is preferable. Although the TOF-SIMS technique is destructive, the probing beams have microsized diameters so that only small portion of the questioned sample is necessary for the analysis, leaving the rest available for other analyses. In this study, TOF-SIMS and attenuated total reflectance Fourier transform infrared (ATR-FTIR) were applied to the analysis of several different pen inks, red sealing inks, and printed patterns on paper. The overlapping areas of ballpoint pen writing, red seal stamping, and laser printing in a document were investigated to identify the sequence of recording. The sequence relations for various cases were determined from the TOF-SIMS mapping image and the depth profile. TOF-SIMS images were also used to investigate numbers or characters altered with two different red pens. TOF-SIMS was successfully used to determine the sequence of intersecting lines and the forged numbers on the paper.

Occupational hazards in printing industry

This paper, through certain printing techniques, examines the types of occupational pollutants and the adverse impacts of the printing process. Also, it proposes the measures for better preservation and environmental protection. The paper analyzes the results of the quantitative identification of hazardous materials from various printing techniques: pad, screen, offset, flexographic, and digital. The study included the analysis of waste printing inks and purification of printing wastewater with adsorption methods. Besides that, the preliminary monitoring of ambient indoor air quality was performed. The multiple regression analysis was applied on the obtained experimental results, in order to determine the mutual correlation between the ozone and the total volatile organic compounds and microclimate parameters. It was observed that a quantitative correlation exists between the investigated occupational hazards, which also indicate the strength of the agreement. The obtained results could be useful to evaluate the tendency of hazardous air pollutants in printing industries worldwide.

Forensic Discrimination Potential of Video Spectral Comparator and Micro Spectrophotometer in Analyzing Question Document and Fraud Cases in India

The aim of the study was to evaluate the discriminating power of non-destructive methods, including optical methods likes the Video spectral comparator method (VSC) and Micro spectrophotometer (MSP) used to differentiate ballpoint pen ink which is commonly used in question document and fraud cases in India. Documents have been investigated to determine the feasibility of utilizing the Video spectral comparator method (VSC) and Micro spectrophotometer (MSP) for the differentiation and comparison of inks on paper. The work focused on how to develop the most effective procedure to ensure quality, when Micro spectrophotometer is used to differentiate writing materials by characteristics color scan of each ink. Six different commercially available blue ballpoint pen inks produced from most popular pens in Indian Market which were used as research material. We have studied most selling pens in Indian market (Reynolds, Parker, and Lexis 2 types, Cello griper and local made pen) for overwriting, alternation and modification of ballpoint pen ink on documents. These pens are generally used on questioned document in forensic discrimination cases and these questioned documents cases received by forensic science laboratories regularly. In forensic discrimination cases generally initial writing is overwritten by using other ink and to identify which ink was used to overwrite is challenging task in field of forensic science. The present study highlighted that the Video Spectral Comparator method (VSC) and Micro spectrophotometer (MSP) can be used routinely in such types of document cases and it has demonstrated to be an excellent analytical method for the forensic analysis of inks on a questioned document.

HPLC and HPLC/MS analysis of red ink on counterfeit 100-yuan notes

Counterfeiting is a significant problem for most major currencies and has high social and economic costs. Chemical and physical identifiers that are unique to counterfeit currency are critical to forensic analysis. The 100-yuan Chinese note is mostly red. Here, we analyzed the red ink used in 100-yuan Chinese notes and developed a method to extract and analyze these dyes via high performance liquid chromatography (HPLC) and HPLC/mass spectrometry (MS). We used this approach to analyze the chemical structures of the adulterated colorants from 46 counterfeit 100-yuan notes seized from different locations. The results showed that a variety of inks were found among the seized counterfeit notes from different sources. The chromatographic data signature could be used to clearly discriminate authentic from counterfeit notes, but could also potentially be used to trace the notes to the counterfeiter. To the best of our knowledge, this is the first report to use HPLC/MS to profile red dyes in Chinese currency with important implications for the forensics and law enforcement communities.

Analysis of red inks by micellar electrokinetic capillary chromatography with laser-induced fluorescence detection.

A combination of MEKC with a--highly sensitive but not commonly used--LIF detector was tested regarding the possibility of differentiation of red inks. The separation process was conducted in a fused silica capillary (id 50 μm, 60/50 cm total/effective length) in BGE consisting of 40 mM sodium borate, 20 mM SDS and 10% v/v ACN with 30 kV applied. The optimized temperature of storage and capillary was 10 and 25°C, respectively. The samples were prepared using 20 dots (ø 0.5 mm), extracted in 35 μL BGE and diluted with 30 μL of water. The proposed method showed excellent repeatability and reproducibility (RSD (tm ) < 0.8 and < 2.5%, respectively). It was applied to group identification and differentiation of different brands, models, and batches of red printing, stamp, and pen inks. It was demonstrated that differentiation can be performed effectively on the basis of migration times and ratios of peak areas. The high efficiency of the developed method was indicated by discriminating power ranging from 87.3 to 98.8%, for stamp and pen inks, respectively. The results showed that the proposed procedure can be valuable for an objective examination of the red parts of questioned documents.

“A Sensitive Non-destructive Method for Detection of Document Frauds using Thermal Ink”

Ink analysis in forensic document examination is a great challenge today. Number of formulations of inks are available. Out of them some tricky ink formulations are routinely used to commit financial crimes related to cheques, will, deed, bills, contracts and other documents. Thermal Ink is one of the formulations which are used in frauds due to its unique characteristic that it disappears on application of heat above a specific temperature. Disappeared writings in thermal inks are not visible to naked eye. This disappeared ink on documents is not visible even with instruments under 0–300 nm UV range, under IR, transmitted lights, oblique lights, and high resolution magnification. Investigation of such types of cases/ documents have become a challenge due to paucity of research and literature. Here, we deciphered this type of ink on different papers and articles with the help of VSC-6000/HS. The main aim of this research work is to develop simple, rapid, sensitive, eco-friendly, portable, economically viable, and non-destructive method to retrive original disappeared writings of thermal ink. The research in such field will be directly beneficial to society as well as law and enforcement agencies which give additional motivation to do research for questioned document.

Improvements to a Grating-Based Spectral Imaging Microscope and Its Application to Reflectance Analysis of Blue Pen Inks.

A modified design of a chromatically resolved optical microscope (CROMoscope), a grating-based spectral imaging microscope, is described. By altering the geometry and adding a beam splitter, a twisting aberration that was present in the first version of the CROMoscope has been removed. Wavelength adjustment has been automated to decrease analysis time. Performance of the new design in transmission-absorption spectroscopy has been evaluated and found to be generally similar to the performance of the previous design. Spectral bandpass was found to be dependent on the sizes of apertures, and the smallest measured spectral bandpass was 1.8 nm with 1.0 mm diameter apertures. Wavelength was found to be very linear with the sine of the grating angle (R(2) = 0.9999995), and wavelength repeatability was found to be much better than the spectral bandpass. Reflectance spectral imaging with a CROMoscope is reported for the first time, and this reflectance spectral imaging was applied to blue ink samples on white paper. As a proof of concept, linear discriminant analysis was used to classify the inks by brand. In a leave-one-out cross-validation, 97.6% of samples were correctly classified.

Spectroscopic analysis of pigments and inks in manuscripts. III. Old-Slavonic manuscripts with multicolored rubication

Raman spectroscopy, FTIR spectroscopy and SEM-EDS were applied in characterization of pigments and inks in five old-Slavonic manuscripts: Kičevo Four Gospel (16th century), Zrze Four Gospel (16th/beginning of 17th century), Struga Four Gospel (beginning of 17th century), Kruševo Ochtoechos (second half of 15th century) and Psalter with rituals (beginning of the 16th century). The illuminations used in the first four manuscripts are in so called Balkan style characterized with interlaced rings and floral motifs, with rarely seen, multicolored rubication text: in Kičevo and Zrze Four Gospel manuscripts are written in four colored inks: black-brown, blue, red and purple-red while in Struga and Kruševo Ochtoechos manuscripts is black-brown, blue and red inks. Psalter with rituals is a manuscript from the same period, with typical rubication in red and was included in the study as standard form of manuscript. In addition to several types of gall ink identified as brown-black ink used in the manuscripts, carbon black ink and logwood ink were also identified. In colored inks, azurite or mixture of azurite and indigo were used as blue ink while vermilion or mixture of vermilion and red lead was used as red ink. Another, purple-red ink of organic nature was used as well. The pigments identified in ornaments are: azurite and indigo in blue colors, orpiment as yellow pigment, vermilion, red lead and organic red pigment as reds, while green pigment was identified as organo-Cu complex. Brown-black ink was used for framing the illuminations and illuminated initial letters and pure gold for gilding. In spite of similar style and pigments, slight but characteristic differences in pigments and inks used, suggest different scriptoria.

Forensic analysis of ballpoint pen inks using paper spray mass spectrometry.

A novel analytical approach based on paper spray mass spectrometry (PS-MS) is developed for a fast and effective forensic analysis of inks in documents. Ink writings made in ordinary paper with blue ballpoint pens were directly analyzed under ambient conditions without any prior sample preparation. Firstly, the method was explored on a set of distinct pens and the results obtained in the positive ion mode, PS(+)-MS, demonstrated that pens from different brands provide typical profiles. Simple visual inspection of the PS(+)-MS led to the distinction of four different combinations of dyes and additives in the inks. Further discrimination was performed by using the concept of relative ion intensity (RII), owing to the large variability of dyes BV3 and BB26 regarding their demethylated homologues. Following screening and differentiation studies, the composition changes of ink entries subjected to light exposure were also monitored by PS-MS. The results of these tests revealed distinct degradation behaviors which were reflected on the typical chemical profiles of the studied inks, attesting that PS-MS may be also useful to verify the fading of dyes thus allowing the discrimination of entries on a document. As proof of concept experiments, PS-MS was successfully utilized for the analysis of archived documents and characterization of overlapped ink lines made on simulated forged documents.