Classification and Identification of Photocopying Toners by ... - Library

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MAZZELLA ET AL. 9 PHOTOCOPYING TONERS 835 % ' ; ' I ' ' ; ' I ' ' ' I ' ' ' ' I ' 4000 3000 2000 1500 1000 wavenumbe~ (1/era) FIG. 13--Compartson between the diffuse reflectance spectra of toner extracted from (A) a photocopy produced in the USA on a Canon PC-5 (Collaborative Testing Services, Inc.) and (B) a photocopy produced in Switzerland on a Canon PC-20, These two desk-top machines probably use the same toner. A 400 V 3000 2000 1500 1000 wavenumbe~ (1/era) FIG. 14--Diffuse reflectance spectra of toner samples extracted from a photocopy produced on a Xerox 5052: (A) before treatment and (B) after treatment with the fingerprint development reagent DFO.
836 JOURNAL OF FORENSIC SCIENCES ? ' ' ' ' I ' ' ' ' I ' ' ' ' I ' ' ' I ' ' 4000 3000 2000 1500 1000 wavenumbe~ (l/era) FIG. 15--Diffuse reflectance spectra of toner samples extracted from a photocopy produced on a Canon NP-6550: (A) before treatment and (B) after treatment with physical developer. by this method has allowed the classification of 149 different toners into 36 distinct groups. This indicates a high discriminating power for the technique. It is possible, however, that the application of a complementary technique, such as pyrolysis gas chromatography, may further subdivide toners located within the same group [6]. The pyrolysis gas chromatography of a number of the toners analyzed in this present study has confirmed this possibility; however, a full evaluation has not yet been conducted. In addition to the remarks contained in our previous article [2], we are able to confirm the following: 1. There does not appear to be any significant differences between batches of the same brand of photocopying toner that can be detected by the DRIFTS technique. This con- clusion is justified in that no differences were detected between photocopies produced over an extended period of time on the same machine or between copies produced on different machines of the same brand and model or different machines which use the same toner (different batches of toner would have been involved in these cases). Of course, if the manufacturer introduces a significant variation in the composition of a particular toner between batches, this will be detected by infrared spectroscopy. No example of such a variation has yet been detected. 2. Toner samples from photocopies produced over an extended period of time on the same machine give identical infrared spectra. This is true, of course, only if the rec- ommended toner is continually used in a particular machine. If the brand of toner is changed, differences may be expected in the corresponding infrared spectra. As stated above, a change in the batch of toner does not seem to have an effect. 3. The application of fingerprint development reagents to a photocopy does not sig- nificantly affect the infrared spectrum of the toner. It appears that the reagent residue that remains on the document is not in sufficient quantity to influence the infrared analysis of the toner.
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Classification and Identification of Photocopying Toners by ... - Library

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