Pyrolysis GC-MS
Definition
Heating a tiny polymer sample (about 1 microgram) to roughly 600 to 800 degrees Celsius in an inert atmosphere, separating the volatile fragments on a GC column, and identifying them by mass spectrometry. The fragment pattern fingerprints the binder polymer.
- Temperature range
- 600 to 800 degrees Celsius
- Sample size
- Approximately 1 microgram
- What it identifies
- Binder polymer type in paints and synthetic polymer identity in fibers
Common questions
How does pyrolysis GC-MS identify a paint sample?+
Pyrolysis GC-MS heats a tiny paint sample (about 1 microgram) to 600-800 degrees Celsius in an inert atmosphere. The heat breaks down the binder polymer into smaller fragments. These fragments are separated by gas chromatography and identified by mass spectrometry, creating a unique pattern that fingerprints the binder.
Why use an inert atmosphere during pyrolysis?+
An inert atmosphere prevents the sample from oxidizing or reacting with oxygen during heating. This ensures the decomposition produces only the true breakdown products of the polymer, giving a reliable fingerprint for identification.
Can pyrolysis GC-MS identify synthetic fibers the same way it identifies paints?+
Yes. The technique works on both. A synthetic fiber is heated to 600-800 degrees Celsius in an inert atmosphere, breaking down into fragments that are separated and identified by gas chromatography and mass spectrometry. The resulting pattern confirms the polymer type of the fiber.
Related terms
- Binder
- The polymer matrix that holds pigments in place and bonds the paint to the substrate. Identifies paint type (alkyd, acrylic, polyurethane, epoxy)...
- Birefringence
- The difference between the highest and lowest refractive indices of an anisotropic mineral, seen as a characteristic interference colour between crossed polars....
- Cross-Section Mount
- Embedding a paint chip in resin, polishing to a flat face, and viewing under reflected light at 100 to 400 times magnification...
- Cross-Section Shape
- The geometry of a fibre when sliced perpendicular to its length. Round (nylon), trilobal (some carpet polyesters), dogbone (acrylic), kidney-bean (cotton lumen),...
- Lacquer
- Clear or pigmented coating that dries purely by solvent evaporation (no chemical cure). Nitrocellulose and acrylic lacquers are the classic examples. Fast...
- Microspectrophotometry (MSP)
- Visible-range spectrophotometry conducted through a microscope, generating an absorbance curve that fingerprints the dye on a single fibre without destroying it.
- Paint
- Pigmented liquid coating that dries to an opaque, coloured solid film. Built from four functional components: binder, pigment, solvent (vehicle), and additives.
- PDQ (Paint Data Query)
- RCMP-maintained international automotive paint database. Stores binder, pigment and layer data for vehicle original-equipment finishes from major manufacturers. Used to narrow a...
- Pigment
- Insoluble particles that give colour and opacity. Titanium dioxide (white), iron oxides (red/brown), carbon black (black), organic colorants (blues, reds). SEM-EDX reports...
- Tape Lift
- Adhesive tape pressed onto a substrate to recover fibres, hairs and other particulates. The standard collection method for fibres on clothing, upholstery...
- Varnish
- Transparent, hard protective film made from a drying oil, resin and solvent. Cures by oxidation (oil varnish) or polymerisation (polyurethane varnish). Used...
- Yarn Twist
- The number of turns per unit length and the direction of twist in a yarn. S-twist and Z-twist are the two standard...
Explained in these topics
- Fiber and Textile Evidence: Yarns, Weaves and Microscopic ExaminationThermal decomposition of a fibre at 600 to 800 degrees C in an inert atmosphere, with the breakdown products separated and identified by gas chromatography mas...
- Paint, Lacquer and Varnishes: Nature, Composition and Forensic ExaminationHeating a tiny polymer sample (about 1 microgram) to roughly 600 to 800 degrees Celsius in an inert atmosphere, separating the volatile fragments on a GC colum...