Volume 36, Issue 3 (May 1991)
Classification and Identification of Photocopying Toners by Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS): II. Final Report
A diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) technique has been employed to record the IR spectra of 152 different black and color toners used in photocopiers and laser printers. Based on characteristic absorption bands in the infrared (IR) spectra, 149 of these toners were classified into 36 distinct groups. A small sample of toner was removed from the surface of a questioned document (produced on a photocopier or laser printer), the IR spectrum was recorded using the diffuse reflectance technique, and the class of toner was determined by comparison with a collection of standard spectra. A knowledge of the compatibility of each type of toner can then be employed to provide a list of photocopying machines (or laser printers) that could have produced the questioned document. The technique does not appear to be affected by the age of the photocopy, the batch or toner, or the prior treatment of the questioned document with a fingerprint development reagent such as ninhydrin.