Degradation of alpha-pinene on Tenax during sample storage: Effects of daylight radiation and temperature

The behavior of alpha -pinene sampled on adsorption cartridges filled with Tenax TA has been investigated in relation to different storage conditions, focusing on daylight radiation and temperature. After sampling, the respec tive cartridges containing the terpene were placed in sunlight on the windo wsill for up to 1 month. Corresponding samples have been wrapped in aluminu m foil to prevent the influence of daylight radiation. Additional sample ca rtridges with a-pinene were stored in the refrigerator at 4 degreesC and a freezer at -18 degreesC. All cartridges were analyzed using thermodesorptio n injection onto a gas chromatograph, and the compounds were detected using either a cryocondensation-interface to a Fourier transform infrared-spectr ometer (GC/ FT-IR) or the flame ionization detector (FID). In summary, 12 c ompounds were detected and identified, from which eight were products that were formed on Tenax through different mechanisms. Two com pounds seemed to be formed under the influence of daylight radiation, while the others appe ar to be mainly autoxidation products. Estimates after 1 month of storage s howed recoveries of over 99% for wrapped samples, while for unwrapped cartr idges only about 88% of alpha -pinene was found. A pattern of up to five co mpounds was found that can be used as an indicator for storage reactions.