V. Komolprasert et al., DETERMINATION OF BENZENE RESIDUES IN RECYCLED POLYETHYLENE TEREPHTHALATE (PETE) BY DYNAMIC HEADSPACE GAS-CHROMATOGRAPHY, Food additives and contaminants, 11(5), 1994, pp. 605-614
A dynamic headspace-gas chromatography (HS/GC) method was developed to
quantitate benzene in recycled PETE material derived from 21 PETE bev
erage bottles. The analytical system consisted of a purge-and-trap app
aratus which was interfaced directly with a gas chromatograph/flame io
nization detector. Cryofocusing and non-cryofocusing GC systems were u
sed. The technique was applied to spiked PETE test samples which were
prepared at various benzene concentrations ranging from 100 ppb to 117
ppm. The initial spiked benzene concentration in the PETE test sample
s was determined gravimetrically. The HS/GC technique was limited by t
he slow desorption rate of benzene from the PETE matrix; as a result,
multipurges were performed at 60-degrees-C. Regression analysis was do
ne on the multipurge data to develop a desorption model which would pr
edict the total amount of benzene in the PETE. The calculated results
agreed with the experimental recoveries within +/- 10%. Recovery depen
ded on the initial benzene level in the PETE and ranged from 70 to 90%
after the first five purges.