Ink Dating by the Examination of Solvent of Ball Point Ink by UV-Vis Spectroscopy

Suryanshi Biswas^*
*Correspondence: Suryanshi Biswas, Department of Forensic Science, Amity Institute of Forensic Sciences, Noida, India, Tel: 9456481507, Email:

Keywords

Ink dating • FTIR-ATR • UV-Vis spectroscopy • Solvent extraction method

Abbreviations

UV: Ultraviolet; Vis: Visible; IR: Infrared; TLC: Thin Layer Chromatography; GC: Gas Chromatography; FTIR-ATR: Fourier Transform Infrared Spectroscopy-Attenuated Total Reflectance

Introduction

Writing ink is the most common technique to document the information on a paper. It is used from ancient times, previously the writing instrument were brushes, sticks, bamboo etc. Modern writing instruments like pen have specialized inks [1]. These writing inks are made up of colorant, solvent, stabilizer and additives. Inks are of two types, oil-based and water-based. Oil-based inks include ballpoint pen inks, whereas water-based includes pilot pen inks, fountain pen inks etc. The colorant in oil-based pens are pigments and in waterbased pens, it is dyes. Solvents are usually alcohols; these are also called vehicles. Stabilizers are used to prevent the ink from clotting and make the ink smoother to flow. Other additives are used to improve other quality of the ink [2].

Writing ink have colorant, the visible component of any ink. Colorant in ink can be of two types; pigment and dyes. Pigments are present in glycerol-based inks, whereas dyes are present in waterbased ink. Pigments are usually finely grounded colored particles suspended in solvent. These pigments form a thin layer on the surface of the paper while writing. Dyes stain the paper material and make the writing visible. Dyes are tended to fade faster than pigments. Solvents are the vehicle of an ink; all the components of an ink are suspended in it. The solvent should be volatile in nature, so that after writing it should vaporize leaving the colorant on the paper. That’s why the solvents are alcoholic in nature e.g., acetone, propyl alcohol, propylene glycol etc. Ballpoint pen have oil-based solvents and fountain pen have water-based solvents. Stabilizers are used to give the ink better flow. It gets attached to the molecules of the ink and prevent them to adhere with each other [3]. This makes the ink smooth in texture too. These are basically the polymers of large molecules. In the ancient times, plant resin and egg albumin were used as stabilizers in the ink. Other additives include chemicals which maintain the pH of the ink, because if the pH of the ink is not maintained it can destroy the paper as well as the pen. Petroleum products to lubricate the ink. Ink tags, specific to the manufacturer to identify the ink. Many researches were conducted to find the age of the ink but it’s still not accurate and contain error [4].

In this paper, we collected documents of different ages written with same brand of Ink on a same type of paper and we performed comparative study using the instrument UV-Vis spectrophotometer and we also performed FTIR-ATR on the ink sample to know the component of the ink.

Materials and Methods

The first step of ink extraction is to identify the type of ink e.g., if it is an oil-based ink or water based or any other ink. As water-based inks are soluble in water but other type of inks or oil-based inks need strong organic solvents to dissolve. We can use traditional method of extraction, i.e., moist the cotton or gauge with respective solvent and gently rub the cotton on the ink, the ink will be transferred to the cotton. The other technique of ink extraction can be cutting the part of the paper into small pieces (1 cm²) and performing solvent extraction technique. We can also use syringe needle and plunger to punch out the ink from the document and then place it in a test tube and put few drops of solvent and dissolve the ink in the solvent. Advance techniques include TLC and GC [5].

For isolation of Ink from the documents, we selected traditional method of ink isolation i.e., solvent extraction.

Selection of solvent for ink extraction

Common solvents in ball point pen includes alcohols, polyhydric alcohols and glycol monoethers. That also means Inks are readily soluble in these.

• Examples of the alcohols includes ethanol, propanols, butanols, iso-butyl alcohol, tert-butyl alcohol, pentanols, benzyl alcohol and other various higher alcohols.
• Examples of the polyhydric alcohols include glycols having 2 or more carbons and 2 or more hydroxyl groups within the molecule, Such as ethylene glycol, diethylene glycol, etc.
• Examples of the glycol monoethers include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, etc. Also, glycol monoesters can be used similarly to the glycol monoethers [6].

The solvent we selected for isolation of Ink is Isopropyl alcohol for blue and black ball point ink and red ball point ink was readily soluble in pyridine. Red ball point ink was not soluble in isopropyl alcohol.

Isolation of ballpoint pen ink (blue and black)

We collected some documents of different dates ranging from 2019 to 2022 and used traditional method of ink isolation i.e., we cut the document into 1 cm² pieces and placed those pieces in the glass beaker and poured isopropyl alcohol in it (3 ml each). After sometime, we noticed that the ink started to separate from the document. We removed the paper pieces and the ink was isolated in the alcohol. We tried different brands and different aged inks [7]. The method is working in all the inks. Instead of TLC, we will use this method as the method is quick and cheap. Later, we collected some documents of different dates ranging from 8/2019, 9/2019, 10/2019, 11/2019, 01/2020, 02/2020 and 03/2020. The pen brand used for these documents is cello fast-O ball point pen. We used traditional method of ink isolation i.e., we cut the document into 1 cm² pieces and placed those pieces in the glass beaker and poured Isopropyl alcohol in it (3 ml each) as shown in Figure 1. After sometime, we noticed that the ink started to separate from the document as shown in Figure 2. We removed the paper pieces and the ink was isolated in the alcohol. We tried same brands of different aged inks [8]. The change in intensity of the color of the ink can be seen. We collected black ink sample from 11/2019 and tried this method and isolated the ink successfully but this method is not working for red ballpoint pen ink. Aniline gives partial isolation of red ink. Red ball point ink was successfully isolated by pyridine.

Figure 1. Glass beaker and poured isopropyl alcohol in it (3 ml each).

Figure 2. Ink started to separate from the document.

FTIR-ATR

For the identification of the component of the ink, FTIR-ATR was performed on one of the samples. FTIR-ATR is a non-destructive technique used to identify the component of the chemical without any error. The technique is very sensitive and the results are taken with extreme care. The results of the FTIR are shown below in Figures 3 and 4.

Figure 3. The results of the FTIR.

Figure 4. The results of the FTIR.

UV-Visible spectrophotometer

After the isolation of ink, the sample were placed in UV-Visible spectrophotometer at 500 nm and 600 nm wavelength and the absorption reading were noted with the samples, blank and the reference. The reference was the ink of same brand written freshly on the same type of paper [9]. To avoid the difference in the ink tags, the reference pen was manufactured on the same time with other pens. The blank contains isopropyl alcohol without ink.

Results and Discussion

In court of law, many cases involved disputed documents. These cases can be solved if we can calculate the age of the documents. When it comes to identifying the age of the document, the best method is to identify the age of the ink. Age of ink or ink dating can be calculated by various technique. Earlier in 1968, for ink dating, the identification of the composition of ink and to compare it from the standards in the ink library was done. The ink composition can be determined by TLC. Later on in 1975, with the modification of writing inks, the ink manufacturers started to add specific tags in the ink which can be identified for ink dating. Recently, the relative age comparison test or relative ink dating is done with the ink which have same formulation, same writing time or date and on the same type of paper or document. For relative ink dating, researcher developed many new methods and instrumentations. Method like solvent extraction (Rate determining procedure), it is premise that the longer the time ink had been placed on the paper, the more difficult it will be to dissolve in the solvent. But this method is not highly reliable and the chances of error is more. The second method is Fourier Transfer Infrared Spectroscopy (FTIR), as the solvent of the ink is volatile in nature and have alcohol group in its component and with time it can show variation. Many age versus several ratio of IR peak absorbance was observed. But this topic needs more experiment and result to produce more accurate results. Recent research by Cantu and Prough, they discovered a new technique for ink dating, it is called Extraction Rates by fluorescence analysis and they discovered the fluorescence component of the ink solvent and its relative optimum rate determining parameter of the different aged ink. They measured the fluorescent by fluorescence spectrophotometer. But the limitation of this method is that there should be no interference from the paper and also the solvent used for the extraction of the ink should not have any fluorescence components. For the ink with no fluorescence component, this method is not that much useful.

The first step of ink dating is the extraction of the ink and then after extraction the solvent can be analyzed. For analysis purpose, from previous researches we got to know that one can use gas chromatography especially for the detection of volatile component of the ink. We can also use Fourier Transfer Infrared (FTIR) spectroscopy for the detection of different component.

Relative age determinations have been reported using FTIR to detect changes in dried ink with age. In this work the Hydroxyl (OH) and Methyl (CH) Infrared (IR) absorption bands were used. Humecki found a decrease in the ratio of the hydroxyl to methyl bands in 1 ink formulation up to 22 years old with the leveling off beginning around 10 years. Humecki used micro FTIR techniques since he was working with micro samples of ink (1 to 5 ram). Becker, et al., at ATF attempted to verify the usefulness of this technique using micro samples of ink; however, they did not use an IR microscope attachment as used by Humecki. Their results have been unsuccessful so far, perhaps because the optimum experimental procedures were not attained. However, the general trend of agingversus- several ratios of IR absorbance peaks was observed. In all these cases, the ink extract is placed on a KBr window, although ATF also tried mixing KBr and making a pellet. It appears that the success of this technique depends on the extreme care that must be taken in sample preparation and on the use of an IR microscope. The setting of the apertures and placement of the sample in the microscope is critical [10].

The results of FTIR-ATR showed the presence of orange dyes and also other components [11].

The dye component found in the ink are:

• Hematite with a trace of Quartz
• Dicarbonyldichlorobis (triphenulphosphine)ruthenium(II)
• Potassium dicyanoaurate(I)
• Bromopentacarbonyl bromide
• Triruthenium dodecacarbonyl
• Bromopentacarbonylmanganese

After observing these components, the maximum absorption of these components is between 500 nm-600 nm. But the result we got is different from what we had expected. The path length of the spectrophotometer was 1 cm.

The result of UV-Visible spectroscopy is shown in Table 1.

Table 1. The result of UV-visible spectroscopy is shown in table.

Conclusion

Ink dating is a technique which helps us to approximately identify the age of the ink as well as the age of the documents. Every technique has some limitation when it comes to ink dating. In this research, we tried to use the application of UV-Visible spectroscopy in ink dating.

For that, we first used FTIR-ATR for the identification of the ink components and then carefully selected the wavelength at which those components show maximum absorption. The isolation of the ink from the document was done by solvent extraction method i.e., cutting the document into 1 cm² pieces and placed those pieces in the test tube and poured Isopropyl Alcohol in it (3 ml each). After sometime, we noticed that the ink started to separate from the document. We removed the paper pieces and the ink was isolated in the alcohol. Then the samples were examined through UV-Vis spectrophotometer, no direct relation was found between the results i.e., the readings of the spectrophotometer were random at two different wavelengths 500 nm and 600 nm. So, after this experiment, we can conclude that it is not possible to estimate the age of the ink using only UV-Visible spectrophotometer. Combining this technique with advance instruments may show variation in the results. But according to the results obtained in this experiment, we cannot conclude the age of the document or the ink.

Acknowledgements

I would like to express my sincere gratitude to Dr. Manisha Mann, Assistant Professor, NFSU, Delhi for her guidance and valuable support throughout the course of this project. My project would not have been completed without her support.

Authors' Information

The author of this research paper is Suryanshi Biswas. She had completed her Bachelors of Science honors in Forensic Science from Amity University, Noida, India and currently she is pursuing her Masters of Science in Forensic Science from department of anthropology, University of Delhi, India.

Declaration

I hereby declare that the article with the title “Ink dating by the examination of solvent of ball point ink by Uv-vis spectroscopy” submitted is the original work done by me in the guidance and supervision of Dr. Manisha Mann at Amity institute of forensic sciences, Amity University, Noida, Uttar Pradesh.

The work done in the report is genuine and has not been submitted previously for any other Journal.

References

1. Brunelle, RL and AA Cantu. "A Critical Evaluation of Current Ink Dating Techniques." J Forensic Sci 32 (1987): 1522-1536.

   [Crossref] [Google Scholar]

2. Ezcurra, Magdalena, Juan MG Góngora, Itxaso Maguregui and Rosa Alonso. "Analytical Methods for Dating Modern Writing Instrument Inks on Paper." Forensic Sci Int 197 (2010): 1-20.

   [Crossref] [Google Scholar] [PubMed]

3. Weyermann, Céline, Dieter Kirsch, César Costa Vera and Bernhard Spengler. "A GC/MS Study of the Drying of Ballpoint Pen Ink on Paper." Forensic Sci Int 168 (2007): 119-127.

   [Crossref] [Google Scholar] [PubMed]

4. Kiran A. "Analysis of Commonly Used Blue Ballpoint Pen Ink in India by Planar Chromatography." Int J Adv Res 5 (2017): 981–988.

   [Crossref]

5. Kamil, Mustafa, Muhammad Naeim Mohamad Asri, WN Desa and Dzulkiflee Ismail. "Fourier Transform Infrared (FTIR) Spectroscopy and Principal Component Analysis (PCA) of Unbranded Black Ballpoint Pen Inks." Malaysian J Forensic Sci 6 (2015): 48-53.

   [Google Scholar]

6. Ichikawa, Shuuji. "Ink Follower Composition for Oil-Based Ballpoint Pens." U.S. Patent 6,530,708, Issued March 11, 2003.

   [Google Scholar]

7. Hattori, Tetsuya and Katsuhisa Asada. "Ballpoint-Pen Ink Compositions." U.S. Patent 7,297,730, Issued November 20, 2007.

   [Google Scholar]

8. Senior, Samir, Ezzat Hamed, Mamdouh Masoud and Eman Shehata. "Characterization and Dating of Blue Ballpoint Pen Inks Using Principal Component Analysis of UV–Vis Absorption Spectra, IR spectroscopy and HPTLC." J Forensic Sci 57 (2012): 1087-1093.

   [Crossref] [Google Scholar] [PubMed]

9. Jain, Anoop and Ramesh Chowdhary. "Palatal Rugae and their Role in Forensic Odontology." J Invest Clin Dent 5 (2014): 171-178.
10. Sheikhi, Mahnaz, Mohammad Zandi and Maryam Ghazizadeh. "Assessment of Palatal Rugae Pattern for Sex and Ethnicity Identification in an Iranian Population." Dent Res J 15 (2018): 50.
11. Indira, A P, Manish Gupta and Maria Priscilla David. "Usefullness of Palatal Rugae Patterns in Establishing Identity: Preliminary Results from Bengaluru City, India." J Forensic Dent Sci 4 (2012): 2-5.