Some inks fluoresce, or emit light, on exposure to ultraviolet, while others disappear. First extract the ink sample from the paper. Why are some chemicals visible under one type of light but not another? Test, research, develop, and improve products to make them better, safer, and more accessible. The second option should not be confused with the same ink manufacturer producing the same ink formulation for several different ink companies, such as, Formulabs producing the same ink formulation for Parker and Cross blue ball point pens. For this reason this type of tag is commonly referred to as a florescent date tag. Hint: Think about the strength of the attractions. Thus protected, it can be read in transit on both sides and handled without soiling, wetting, or any physical alteration that might modify or destroy elements of the evidence.
This separation only occurs when a solvent is used in which the ink is soluble. This activation drives the water from the plate and allows for better separation of the dyes and more accurate measurement and calculation of the relative intensities of the individual dye ratios. We have already discussed environmental engineering situations that require water remediation. Many people put much more pressure on combinations of letters found in their own names than on the other letters they type. Some ink will have different components, and thus will have multiple Rf values. With experience, smaller sample sizes of one or two plugs can be used by modifying the amount of solvent used to extract the ink and the manner in which the ink is spotted.
Ink dating — cases: In the following real case examples, one can see the manner in which the three thin layer chromatography tests can be used to aid in examinations. What makes it possible to create high-technology objects like computers and sports gear? Answer: The black ink is more attracted to the isopropyl alcohol. Manufacturers used two types of chemical date tags in their ink formulations. Last modified: March 5, 2018. See the page for details. Ask a few student volunteers to share their answers with the class.
This was also significant since the ink was an ink manufactured by Formulabs, which put date tags in most of their inks during the time period the pen was purchased by the victim. To the naked eye the different inks used to write documents may seem utterly identical. The R f values and the colour of the bands can be recorded and in the case of inks compared to a database held by the United States secret service. The fact that most people fill their fountain pens with different kinds of ink at different times may also serve to identify an individual pen through the unique combination of inks in it. Ink Dating Expert Witness — Document and Handwriting Experts Ink Dating is done in two primary forms. Black ink is a mixture of several different colors.
In reality, it is not very destructive to the document if done with care. This variation is enough to produce visible differences, however, there can be some overlap of R f values and colour is an objective measurement. The discussion should include a summary of results your table of ink types and corresponding Rf values , which lead you to the identification of the unknown ink source. The third is the Dye-Ratio, which measures the relative concentration of each dye to one another. Insert the paper strip into the test tube. This was done in the laboratory in Hong Kong. Raman spectroscopy is a non-destructive, analytical technique based on the scattering of monochromatic light.
These results should then be photographed using ultra-violet light and color film for presentation at a later time if required. Contact Information By postal mail: Central Intelligence Agency Office of Public Affairs Washington, D. The determination of the type of writing instrument is probably the oldest method of ink dating. Identification of ink is possible by thin layer chromatography fingerprinting. Main Office: Speckin Forensic Laboratories 2601 Coolidge Rd. The police and other investigators use chromatography to identify clues at a crime scene like blood, ink, or drugs.
We cannot see each of these individual components unless a separation occurs. A comparison is then made between the sample or samples being analyzed to the known or control standard. It can be established that a document is forged by showing that its paper is not as old as its purported date. This is your spotted sample as shown in Figure 4 below. This was a single tag was could be extracted with the ink, separated and analyzed with ultra-violet light.
Many other similar examples exist. Another solvent for non-ballpoint inks to use is ethanol and water mixed at a ratio of one to one. Wrap-Up Discussion: At lab end, bring students together as a class and ask them the following questions about how chromatography works, what happens to the ink during this process and its real-world relevance. Chromatography is a technique used to separate the various components in a complex mixture or solution. Materials scientists and engineers think atomically meaning they understand things at the nanoscale level , but they design microscopically at the level of a microscope , and their materials are used macroscopically at the level the eye can see. Percent extraction curves were plotted as percent extraction vs.
This makes the 3-minute extraction value 1. Third Party: Have someone you trust travel to a less restrictive environment and deliver the information via one of the above methods. When you put your project in the hands of our specialists, you can expect results that reflect the unparalleled knowledge of scientific minds of the forefront of positive change. This may seem to be a large number at first glance, however with a large library of inks, significant knowledge and experience becomes extremely useful when applied to casework and also to expressing the significance of conclusions as to the uniqueness of individual dye components. Intertek tests and analyzes colourants, dyes and pigments and their formulations into liquid inks and materials, from printed packaging, pharmaceutical marking and coatings and food. Speckin Forensic Laboratories is an International forensic firm specializing in consulting with plaintiff and defense lawyers involving issues concerning: , , , , , , , , , , , , , , , , , , , , , and.
Waterman, for example, has changed formula four times in ten years, so that a sample of Waterman's may often be associated with a particular period of manufacture. This is your solvent, or mobile phase. The ink dating static approach is typically more useful as the difference between the date on the document and the present time increases. Usually dye analysis would be used to lend weight to a conclusion suggested by other evidence. This addition was made sometime in 1996.