Forensics Journal - Stevenson University 2011 | Page 17

FORENSICS JOURNAL Determining the Effects of Ranging Reagent Grade Solvents on Thin-layer Chromatography Ink Analysis Using Solvent System I (Ethyl Acetate: Ethanol: Water) Julia Wikoff ink formula can be identified, if two separate writings have a common origin, and to date the ink. Dr. Neumann and Dr. Margot published Consideration on the ASTM Standards 1789-04 and 1422-05 on the Forensic Examination of Ink. They noted that the ASTM standards stated that appropriate materials need to be chosen to minimize variability, but did not provide details regarding these materials [3]. The guidelines do not specify the solvent grades needed for Solvent System I: (ethyl acetate: ethanol: water) (70:35:30). INTRODUCTION A field of significant importance within Forensic Science is questioned documents. A document with any doubt as to the author, date written, or age is a questioned document, and may include printed materials such as letters, drivers’ licenses, contracts, passports, lottery tickets, and checks. Writings or markings found on larger objects such as walls or doors are also included in this field. A document examiner must be skilled in non-destructive techniques such as non-flash photography and microscopy as well as destructive techniques such as thin-layer chromatography [4]. Examinations of questioned documents can involve determining the type of paper and/or ink used to write the document as well as determining the author of the document. Two main types of inks are currently on the market today. Two-thirds of the available inks are non-ballpoint inks. These water-based inks are visualized as glossy and fluid on a paper; they commonly bleed through a thin piece of paper. Since the inks are water-based, the dyes are dissolved in ethanol: water for analysis. One-third of available inks are ballpoint inks. These glycol-based inks leave metallic appearing striations on paper and commonly leave a well when writing because pressure must be exerted to release the ink. The glycol-based inks are dissolved in pyridine. Crimes involving questioned documents include larceny, forged wills, identity theft, ransom notes, traced signatures, altered medical records, watermarks, signatures on legal documents, pre- and postnuptial agreements, and death threats. Questioned documents could be typed or written in ink, pencil, marker, blood, or other bodily fluids. Most altered documents are written with “white-collar criminal intent” [2], but some are written with darker purposes including kidnapping and murder. A document examiner must consider all the characteristics of a document including “the writing medium used and the surface it is written upon, the age of the paper or ink, and watermarks” [2]. This study was conducted to determine if different grades of solvents in Solvent System I produce inconsistent chromatography plates. The separation and clarity of the ink components and the reproducibility of the Rf values were both studied to determine the solvent system combination that produced the best results. MATERIALS AND METHODS Questioned documents are commonly encountered in the forensics field. If ink from a writing instrument, printer, or typewriter is used to create the document, then thin-layer chromatography can be used to determine the manufacturer of the ink. The separation of the ink components is viable on a chromatography plate by the appearance of individual colored bands. The retention factor, Rf, can be used to identify a specific ink by using a library of previously run Thin-layer Chromatography (TLC) plates. The United States Secret Service Forensic Science Division currently has the largest library of ink types with a collection of over 10,800 ink samples. Sample and Solvent System Preparation: A total of fifty black and blue inks were chosen for analysis. Twentyfive of the chosen inks were ballpoint and twenty-five were nonballpoint. The brand, color, and classification of each ink can be seen in Tables 1 and 2. Five Kimble glass Ink Opticlear® 12 X 35 mm vials were labeled according to the classification of each ink. The inks chosen were available on scribble sheets, labeled in binders and written on using the matching ink. A micro-punch was used to collect between four and eight 1 µm micro-punches of each ink for each of the five glass labeled vials. The American Society of Testing and Materials (ASTM) created a “Standard Guide for Test Methods for Forensic Writing Ink Comparison” in 2008 [1]. These guidelines are followed to determine if the 15