Skip to main content
Chemistry LibreTexts

Pen Ink

  • Page ID
    66556
  • \( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \) \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)\(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\) \(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\)\(\newcommand{\AA}{\unicode[.8,0]{x212B}}\)

    Spectroscopic and Chromatographic Analysis of Pen Ink

    Objective

    To determine the color and composition of pen inks and inked writing found on documents pertinent to the case.

    Sample

    Collect a variety of ballpoint and felt tip pens and prepare documents with those pens. Assign pens and documents to the suspects and to the crime scene.

    Reagents

    Extraction fluid and mobile phase: aqueous 0.005 M heptanesulfonic acid and acetonitrile mixed in 45:55 ratio.

    Standard Reference Material

    None

    Methods

    Visible spectrophotometry; liquid chromatography

    Special equipment

    UV-Vis spectrophotometer; pair of small-volume, 1-cm cuvettes; liquid chromatograph with C18 column and diode array detector; 2-mL chromatography vials with screw caps

    Procedure

    For instructor (detailed); For student (brief)

    Typical results

    Visible spectra of felt tip and ballpoint inks; representative chromatograms of two (A and B) pen inks: 20-µL injection of liquid sample; C18 column; isocratic elution with 45:55 aqueous 0.005 M heptanesulfonic acid (pH = 4.7): acetonitrile, flowing at 0.3 mL/min.

    FeltTipSpectra.PNG

    BallpointSpectra.PNG

    FlairChrom.PNG

    SuperballChrom.PNG


    This page titled Pen Ink is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by Contributor.

    • Was this article helpful?