Determination of Paint Thinner in Fire Debris by GC-MS with SPME

The fire debris sample was placed in a metal vessel or plastic bag,sealed tightly and heated at 80 ℃ in an oven for 20-30 min,to change the paint thineer into gaseous state,which was adsorbed on the 100 μm polydimethylsiloxane (PDMS) fibre through a springe needle stuck into the vessel or bag.Five to 10 min were taken for the adsorption,and the springe needle was taken out and transferred into the sample inlet of the GC instrument.It took 2 min for desorption of the paint thineer from the PDMS fibre,which was then analyzed by GC-MS according the prescribed procedure.Constituents of the thinner were identified by comparing the peaks in the spectrum of sample with those in the spectrum of known compounds in simulated samples.