Spectrophotometric Evaluation of Color of Ink Marks on Paper

Abstract

VOLUME19, NO. 12 some specific applications for the determination of iron in solutions of high pH. RECOMMENDED PROCEDURESample. Procure a representative portion of the material and subject it to the necessary preparative treatment. By weight or volume, measure the quantity of sample which contains not more than 6 mg. of iron. Dissolve the sample, if necessary, by appropriate means.Remove those substances which precipitate at pH's greater than 9.5 and check the interference of other ions present, Dilute to 100 ml. Desired Constituent. To a 50-ml. volumetric flask containing a 5-ml. aliquot of the sample, add 3 ml. of the reducing agent (the reducing agent is prepared by dissolving 10 grams of sodium dithionite in 100 ml. of concentrated ammonia and 50 ml. of water. Use of 0.1 to 0.4 grams of the solid sodium dithionite and the subsequent addition of 2 ml. ammonia is more desirable, if an iron-free salt is available) and 0.5 ml. of 1% butanedionedioxime or diethylaminobutanedionedioxime. (Two milliliters of a 0.2% ethanolic solution of 1,2-cyclohexanedionedioxime may be substituted if 6 ml. of the ammoniacal dithio-nite are used, and if transmittancy readings are taken at 543 my.) Allow this to stand for 15 minutes, dilute to volume, and take the transmittancy reading at 529 my for the former and 541 my for the latter reagent. A 30 my spectral band, with these wave lengths at the center, may be used. A method of visual comparison may be used, since these systems obey Beer's law. LITERATURE CITED(1) Bachman, G. B., and Welton, D., private communication.(2) Diehl, H. C., "Applications of the Dioximes to Analytical Chemistry," Columbus, Ohio, G. Frederick Smith Chemical

Characterization of Fountain Pen Inks by Porous Glass Chromatography and Electrophoresis

“…Though well suited for many applications, the investigator often experiences difficulties with this instrument when attempting to obtain spectral transmission data from opaque paper chromatograms. As a result, reflectance measurements are usually taken with some compromise in accuracy (13). Transmission data has been obtained, however, by rendering the paper chromatogram either transparent or translucent using clearing oils and placing the cleared strips between glass plates for scanning (22).…”

Comparison of Ink Writing on Documents by Means of Paper Chromatography

“…Chemical methods have the disadvantage of being difficult to demonstrate in court and of exposing the document to the risk of accidental damage from chemical reagents. Physical methods of analysis which may be used include visual and microscopic examination and comparison using transmitted, reflected, or oblique lighting; fluorescence testing with ultraviolet light; photography with the aid of filters and appropriate films to accentuate color differences in inks; infrared or ultraviolet photography (3,4,5,6,8); long wave length X-rays (7); and reflection spectrophotometry (1). These methods may show differences in writings made with inks of the same type and of similar appearance.…”