THE DESIGN, VALIDATION, AND APPLICATION OF A CUSTOM-BUILT FLASH PYROLYSIS UNIT FOR USE WITH A GC/MS
Open Access
- Author:
- Nunez, William Emilio
- Area of Honors:
- Forensic Science
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Danny Glynn Sykes, Thesis Supervisor
Ralph R Ristenbatt, Faculty Reader
Danny Glynn Sykes, Thesis Supervisor
Danny Glynn Sykes, Thesis Honors Advisor - Keywords:
- forensic science
criminology
fibers
forensic chemistry
flash pyrolysis
chromatography
nylon - Abstract:
- Although numerous thermal degradation studies of synthetic fibers have been published, the majority has been conducted using commercial pyrolyzers. An issue arises, however, when the process of pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) needs to be taught in a training or educational setting, as in college courses or forensic training programs. It is not feasible for these institutions to purchase multiple commercial pyroprobes for over $20,000 a piece, in addition to multiple GC/MS units, in order to allow multiple students to complete a study in a timely fashion. Therefore, the lab has designed and built an inexpensive pyrolysis unit. The question this study asks is “can this custom-built unit provide reproducible results comparable to a commercial instrument that would be useful in a training setting?” Before it was compared to a commercial unit, however, it needed to be confirmed that the custom instrument was providing reproducible results. Tests were performed to identify key differences in the chemical profiles of nylon 6 and nylon 6,6 that have been subjected to various matrix and surface treatments. Previous studies have shown the thermal degradation pathways of these two nylons to be different, thus producing different chemical profiles. The custom-built instrument was able to discriminate between these two nylons, a discrimination that is not as apparent when using other common analytical methods like Fourier Transform infrared spectroscopy (FT-IR) or polarized-light microscopy (PLM). The results from the custom-built instrument were then compared with the commercial instrument. Although the GC/MS, when used with the commercial instrument, was indeed much more sensitive than when used with the custom-built instrument, the same discrimination could be seen in both chromatograms, namely the absence of a large caprolactam peak in nylon 6,6.