NCJ Number
215162
Journal
Journal of Forensic Sciences Volume: 51 Issue: 4 Dated: July 2006 Pages: 925-928
Date Published
July 2006
Length
4 pages
Annotation
This paper describes a new method for thermal desorption of small samples that uses a solid phase microextraction (SPME) holder with the fiber removed; it is demonstrated in a comparative analysis of inks, printing inks, and inkjet inks on paper.
Abstract
Thermal desorption is a widely used technique for extracting and isolating volatile and semivolatile compounds from various matrixes. Almost any sample that contains volatile organic compounds can be analyzed by using some variation of this technique. The technique for thermal desorption described in this paper uses a commercial SPME holder that is available in most modern laboratories. No solvents or liquid nitrogen cooling units are required. This device can be used with any kind of gas chromatographic equipment that has a straight inlet liner. The needle of the SPME holder penetrates the injector septum. The temperature of the thermal desorption is the temperature of the injector. The paper sample is kept inside the holder needle during the analysis. After the analysis is completed, the sample is removed from the needle by pushing forward the steel wire inside the needle in the same manner used to perform sampling with the SPME fiber. The desorbed compounds can be analyzed by gas chromatography with a flame ionization detector or by gas chromatography-mass spectrometry. The optimum temperature for desorption of ink samples on paper was found to be 200 degree C. The influence of the paper matrix was negligible at this temperature. Laboratories that lack the commercial device for thermal desorption can use this cheap device for the analysis of writing ink, printing ink, and inkjet ink samples on paper. Other types of samples can be analyzed, but the size of samples suitable for analysis is limited. 8 figures and 1 reference