Vol. 4, No. 4, Oct/Dec 1998
IDENTIFICATION OF BALLPOINT INKS IN FORGED WRITING STROKES ON DOCUMENTS BY HPLC 1•2 Differentiating similarly coloured inks suspected to be used on altered handwritten entries. by Kun-Chi Cheng, M.Sc. 3 and Chang-En Pu, M.Sc. 4 REFER.E..'"CES: Cheng. K-C and Pu, C-E., "Identification of Ballpoint Inks in Forged Writing Strok£5 on Documents by HPLC", International Journal of Forensic Document Examiners, Oct/Dec, Vol. 4, No. 4, pp. 323-328. ABSTRACT: In many questioned document cases altered ballpoint inks in writing strokes may be differentiated with the aid of the Video Spectral Cornpan!tor (VSC-1) device [1). However, in one case, two similarly coloured ink stroke alterations on a document could not be distinguished by way of the VSC-1. An alternative solution employed "High Performance Liquid Chrornarography'' (HPLC) with associated photo diode array detector (DAD) to separate and distinguish organic dye components in the similarly colour ink strokes. After a series of experiments, we were able to establish an experimental condition that could identify the subtle ink of forged ballpoint ink strokes effectively. 16 different kinds of ballpoint ink (8 blue and 8 black inks) from five factories were obtained for our tests. Each ink was test 3 times for reproducibility, resulting in 48 test samples. The results of the separation by HPLC disclose the 16 inks, two groups of similar colours, to possess their ov.n unique compositions allov.ing them to be distinguished from one another. The results show tha1 the parameters of our HPLC conditions permit the identification of altered ballpoint ink strokes of similar colour to be distinguishable v.ithout factoring conditions such as paper type, ballpoint-pen, writing pressure and other conditions of the sample. From the above experimental results we suggest that by using the HPLC method more accurate judgements can be achieved when attempting to distinguish similarly coloured ink strokes suspected to have been altered. Keywords: Writing inks, alterations, HPLC, _High Performance Liquid Chromatography.
2.
Blue inks:
Platinum BR-8; Reynold 350, Platinum B-7, SKB 202, Re)nold ~5. SKB 2QOO, Platinum BR-7 and OHTO 700GF. /
Black inks:
Platinum B-8, Reynold 350, SKB 202, Reynold 045, SKB 2000, Platinum BR-7, Reynold 040, Classmate 820.
Paper:
Canon 100 pound color copier paper.
3. Solvents[2]:
HPLC: A. Buffer: 1.38 gram NaH 2P04 to dissolve in 1000 c.c. DI-Hp; B. Acetonitrile (MeCN); and C. DI-Hp. 4. Column: Hewlett-Packard ODS Hypersil 200X2.1 mm, particle size 5.0 t-tm. pore diam 120A, pore volume 0.65 mUg, pH range 2-8, surface area 170m2/g. 5.
Device:
HP-100.
6. Conditions:
Introduction Documents may be altered in many ways, however, the most common arc additions to written strokes using a similarly coloured writing ink. Such alterations may be determined upon exposure to different light sources when placed under Video Spectral Comparator (VSC-1). When this fails the questioned inks may be analysed by1bin layer chromatography in an attempt to differentiate strokes in a suspected altered entry. A less used separation approach involves High Performance Liquid Chromatography. HPLC is a well established analytical technique used for a variety of purposes. In forensic science it is widely used in the analysis of body fluids for the presence of illicit drugs. It has also been used to differentiate writing inks. The following research offers an approach using HPLC to differentiate similarly coloured ink strokes suspected to be involved in the alteration of a written entry.
Materials and Methods Materials 1.
Ballpoint pen ink samples:
'Received Dec. 1998, accepted February 1999. Presented at the 50"' meeting of the American Academy of Forensic Sciences, February 1999, San Francisco, CA. 3 Forensic Science Lab, Scientific and Technical Research Center, Ministry of Justice, Investigation Bureau, P.O Box 3562 Taipei, Taiwan, R.O.C. %id. 2
Ink: Acetonitrile (MeCN); dimethylformamide, dichloromcthane, pyridinc.
Flow Speed- 0.5 mUmin. Max pressure of column - 250 bar. Sample stop time - 30 min. Solvent A(buffer) - 90%; Solvent B (Acetonitrile)- 10% and Solvent C(DI-Hp.). E. Gradient change - Solvent gradient change and flow gradient fixed. F. Sample post time- 4 minutes. G. Photo diode array detector spectrum range 190 - 950 tlm. A. B. C. D.
Methods 1. Prepare pen strokes of each of the 16 ballpoint pen inks on the 100 pound Canon colour copy paper. 2. Using a micro-punch, remove a 0.6 cm length of each ballpoint ink stroke into a vial. 3. Extract the ink from the paper using 15 _ul of acetonitrile. 4. Shake each vial for approximately one minute to ensure the ink has dissolved into the acetonitrile uniformly. 5. Inject 10 t-tl of acetonitrile into the HPLC-1100. 6. Inject 3 equal portions of each of the extracted ink solutions into the HPLC-1100. 7. Repeat methods 3-6 for each ink using Dimethylformamide, pyridine, dichloromethanc.
Results Figures 1 and 2 show plots of the peak retention. times for the 8 blue ballpoint inks. Figures 3 and 4 show plots of the peak retention
Copyright© 1998 Shunderson Communication All Rights of Reproduction Reserved
323
International Journal of Forensic Document Examiners
DAD1 A, Sig=2$4,20 Ref=off (INK\INK00049.D) DAD1 8, Slg=350,20 Ref=off (INK\INKCC049.D) 0
Norm.
~ l
I
~ '\.
j,
=~ . . .~-·-
~
le CQ
...-_ ,,
~
_....:.).. 'I':"
·,(
___
~
.
.. ---lti---~'--1''----....
Platinum B-7(Bu)
~----------------~------------~~-----r----~--~----~-----------·----~~
--~o~-----------~s~~-----------~~o~----------1~5~---------~20~----------.2~5~---------m
DAD I A, Sig=254,20 Ref=otf (INK\INKD::XJ48.D) DAD1 8, Sig=350,20 Ref=off (INK\INKOC048.0) . ..,ilnl.
. Reynold 045(Bu)
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Platinum BR-7(Bu) - - - - -
OHTO 700GF(Bu) - - -
0
5
10
15
20
25
Figures 1 (top) and 2 (bottom): Show the peak retention times for the 8 different blue ballpoint pen inks.
324
Copyright© 1998 Shunderson Communications All Rights of Reproduction Reserved
ml
Vol. 4, No. 4, Oct/Dec 1998 DAD 1 A, Sig=254,20 Ref:;;off (INK\1Ni\t:C063.0) DAD1 8, Sig=350,20 Ref:;;off (INK\INK00063.0)
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i~ r-=========~=-=~~~2i:.::::=:::::::::-::::=::=r-.=====.::=- SI<B 2000(Bk)
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f 5
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15
20
25
min
Figures 3(top) and 2(bottom): Show the peak retention times for the 8 different blue ballpoint pen inks.
Copyright© 1998 Shunderson Communication All Rights of Reproduction Reserved
325
International Journal of Forensic Document Examiners
DAD1 A, Sig=254,20 Ref::off (INK\INKOC061.0) DAD1 8, Sig=::BJ,20 Ref=off (INK\INKC0061.0)
~
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-
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Figure 5: Peak retention times for writing strokes tested 3 times. times for the 8 black ballpoint inks Figure 5 shows the reproducibility of peak retention times following 3 repeat tests under the same conditions. Tables I and 2 differentiate the peak retention times for each of the blue and black ballpoint inks. While all of the 16 inks were different, the same coloured inks disclosed the same retention peak. Different ballpoint inks produced from a common source disclosed at least one similar retention peak [3].
Discussion Standard error for the HPLC·llOO was approximately 2%. It was determined that this error could be reduced if all samples were run continuously and without delays in the injection period. A comparison of the HPLC results disclosed that Acetonitrile and p)ridine were the best solvents to dissolve the inks. When these solvents were used to extract the ink and subsequently analysed by HPLC, they kept the 350.2 nrn and 254.2 nrn analytical wavelength in the best range to find the peak retention times of all the ballpoint inks tested. Almost all of the ballpoint ink samples on the paper were composed of some semi·volatile component which dried over a gradual period of time [4]. Generally, the period of ink drying time is from 3 to 5 months. We concluded that if the document in questioned bears a date that is older than 5 months at the time of the HPLC examination and if the volatile component can be shown to still be present, than we· can conclude that the entry is a forgery. Using the HPLC conditions described above and combining these with the VSC-1, it is possible to tackle document questions where variations caused by different paper, subtly similarly coloured
326
ballpoint inks or different writing pressures can be addressed. In summary we first examine the questioned ballpoint ink entries under the VSC-1 to observe any physical difference between the questioned and know entries. The HPLC is then used to examine these same inks for better discrimination. However, it is important to recognize that if the document were subjected to different ambient conditions of temperature and humidity and exposed to sunlight for extended periods, the colour component in the ink may fade enough to affect the accuracy of our technique. To match two ballpoint inks strokes on different papers, the analytical result must be subtracted from the retention time of the paper leaving the retention times of the inks for comparison. The sensitivity of the technique is sufficient for the analysis of subtle similarly coloured ballpoint inks. When using this technique for casework we suggest that the best results will occur when the questioned and reference ink samples are examined in a continuous manner thereby reducing environmental variations which might contribute to the results. Our test on various solvents established that the degree of polarized solvent plays an important role is dissolving the similarly polarized inks. This technique can detect differences between similar inks arising from different production lots at the same manufacturer. This enables a determination as to whether two or document bear inks produced at a common source.
Conclusions 'This study found that questioned ballpoint ink entries of similar colour and possibly different manufacture may not always be differentiated using the VSC-1 [7].
Copyright © 1998 Shunderson Communications All Rights of Reproduction Reserved
Vol. 4, No. 4, Oct/Dcc 1998
Retention time
10.4
5.0
6.7
6.9
8.4
8.7
9.9
± 0.2
± 0.2
± 0.2
± 0.2
± 0.2
± 0.2
Min
Min
Min
M in
M in
Min
l'vlin
Min
Min
Min
V
V
V
V
V
V
V
V
V
V
V
Kind of pen Platinum BR-8(8u) Reynold JSO(Bu) Platinum B-7(Bu)
V
SKB
V
202(Bu) Reynold 045(Bu)
SKB 2000(Bu) Platinum BR-7(Bu) OHTO 700GF(Bu)
V
V
V
13.6
14.0
15.8
16.8
l'vlin
19.1
20.6
± 0.2 ± 0.2 ± 0.2 Min
l\lin
Min
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V V
11.8
± 0.2 ± 0.2 ± 0.2 ± 0.2 ± 0.2
V
V V
V
V
V
V
V
V
V
V
Table 1: The retention time of eight kinds of different blue ballpoint inks strokes (DADI signal 350.2 nm)
Retention time
6.1
7.9
± 0.2
± 0.2
M in
Min
Min
Min
V
V
V
SKB
8.3
9.5
9.8
10.8
M in
V
V
V
V
V
V
V
V
V
V
V
V
V
V
M in
V
SKB 2000(Bk) Reynold 040(Bk) Platinum BR-7(Bk)
10.3
Min
Kind of pen Platinum BR-8(8k) Reynold 350(8k) 202(Bk) Reynold 045(Bk) Classmate 820(8k)
8.0
M in
12.1
V V
V
V
V
V
V
Min
Min
V V
12.8
13.6
± 0.2
M in
l'vlin
V
V
V V
V
V
11.8
± 0.2 ± 0.2 ± 0.2 ± 0.2 ± 0.2 ± 0.2 ± 0.2 ± 0.2 ± 0.2
15.2
15.8
17.5
± 0.2 ± 0.2 ± 0.2 Min
l\·lin
V
V
V
V
1\lin
V V
V
V
V V
V
V
V
V V
V
V
V
V
V
Table 2: Peak distribution of eight kind of different black ballpoint pen ink strokes (DADI signal 350.2 run)
Copyright © 1998 Shunderson Communication All Rights of Reproduction Reserved
327
International Journal of Forensic Document Examiners
The retention peaks of different inks appearing on the same paper can be determined and compared without subtracting the retention peak for the paper. When using this technique is case work a determination must be made of the conditions under which the document was stored to determine if conditions of heat, humidity, light and other conditions might adversely affect the results of the examination. Using the above technique, the comparison of questioned inks of the same or different formulations and occurring on different paper can be accurately judged.
References [I] Harrison, W.R., Suspect Documents: Their Scientific ÂŁ-camination, Frederick a. Praeger Publishers, New York, 1958, pp. 228-238. [2] Hewlett-Packard Peak News, "Micropobe HPLC in Forensic Documents (Tracking a Check Forgery)," 2/HP Peak, 4, 1992. [3] Lee, S.D., "HP-1100 ChemStation HPLC 2D/3D Chinese Hanbook," 1996. [4] Aginsky, V.N., ''Forensic Examination of 'Slightly Soluble' Ink Pigment Using Thin-Layer Chromatography", Joumal of Forensic Sciences, Vol.. 38, No. 5, 1993, pp. 1131-1133. [5] Brunelle, R. L. and Lee, H., "Determining the Relative Age of Ballpoint Ink Using a Single-Solvent Extraction, MassIndependent Approach", Journal of Foreruic Sciences, Vol.. 34, No. 5, 1989, pp. 1166-1182. [6] Lofgren, A and Andrasko, J., "HPLC Analysis of Printing Inks", Joumal of Forensic Sciences, Vol.. 38, No. 5, 1989, pp. 11511160. [7]
Aginsky, V.N., "Comparative Examination of Inks by Using Instrumental Microspectrophotometry", Journal of Forensic Sciences, Vol.. 38, No. 5, 1993, pp. 1111-1130.
328
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