A new single-solvent extraction technique was developed to estimate the relative age of ballpoint inks. The procedure involves extracting the inks with weak solvents, spotting the ink extract onto a thin-layer chromatographic plate and measuring the amount of ink extracted densitometrically. By comparing the amount of questioned ink extracted with the amount extracted by known dated inks, it is possible to estimate the date the questioned ink was written. Success in using this technique depends on finding suitable weak solvents for extracting the ink. It also depends on the ability of the analyst to remove nearly equal amounts of ink from the document for each ink sample tested. This paper describes the results of several experiments for determining the relative age of ballpoint inks using a single extraction technique. Reproducibility measurements, experimental variations, and the limitations of the technique are also reported. Suggestions for further work are proposed.
Ball-point pens and the variety of colored inks that flow from them have been a ubiquitous part of our society for about 50 years. They are the most common of all our writing instruments. The examination of these kinds of inks sometimes becomes important in a legal case, and in a typical crime laboratory, the analysis of the ink used on questioned documents such as contracts, wills, checks, tax returns, threat notes, etc., becomes the responsibility of the forensic chemist. It is the purpose of this paper to describe the typical steps used in the analysis of ball-point ink.The ink that flows from a bail-point pen is not a pure substance, but a complex mixture of many different chemicals.
sions of the divisions of the crime laboratory for evaluating some of the physical evidence. This approach turned out to he a mistake: mosl students were not as knowledgeable as I thoueht thev would be. and. even with instruction in the use of screntific"equipment. they were unable to use and derive benefit from the instrumentation. Bv the time1 realized this.I had lost over 50% of my officers with poorer backgrounds:Needless to say enrollment dropped significantly the next year.During the second year, my objectives were to rekindle the interest of the first year and to assure advisors that the course content was valuable for their students. I switched to a lecture-demonstration method with success. We also realized that not all of the material we considered important could be covered in a one-quarter course with laboratory. Therefore, we divided the material into two one-quarter, nonlaboratory courses.My approach to forensic science has become one of teaching to the level of student understanding, talking neither over their heads nor down to them. The major objectives of the program are to:(1) expose students to the scientific method and show them the importance of science in everyday life, (2) stimulate reading in forensic science, (3) require readings of nonfiction novels dealing with crime (a list of sueeested nonfiction books is available on reauest). .. drwlopan a l d t t y t<, wnfe a tcchtlicd research paper pertaining 1%) Lrrmsic rcicnce, and ( 5 ) tnvohe ~rudrnta in examining artunl court cascr.Our text for fall 1984 was "Criminalistics" by Richard Saferstein (Prentice-Hall, 1984). In addition to the text and scheduled lectures, the class uses a variety of other media including videotapes of Milton Helper's accounts of deaths and violent crimes, and guest speakers on various t o~i c s including rape, fingerprints, tests, etc. A research paper is required in the first course but not in the second because it deals mostly with case studies. Neither course is a prerequisite for the other, and both classes are alwavs open . .for class participation and discussion.Students examine the topics below and determine in which order they should he discussed. These topics are patterned after the divisions of the Georgia State Crime Laboratory and represent the areas of investigation carried out by the scientific staff:(1) Criminalisties: microscopic comparisons of sail, hair, fiber, paint, glass, wood, and cloth; identification of firearms, bullets, cartridee cases, shotgun cases, nitric acid tests for ~owder resi- Involvine students with actual court cases has never heen difficult; infact, every time the courses have been offered we have found new and interesting cases to be discussed in depth. One year, we discussed thk Atlanta Murders because 778Journal of Chemical Education they were local, because one of the task force officers on the case was a class member, and because another class member was an intern a t the Georgia State Laboratory during the court case. The Atlanta Murders presented us with an opportunity...
Example of turmeric as a natural acid-base indicator.
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