Evaluation of Tenax-TA adsorption for the measurement of toxic organic compounds in workplace air using thermodesorption gas chromatography

A method for the measurement of toluene, m,p,o-xylene, styrene and iso, n-butylacetate in workplace air of surface coating industries was developed. The target compounds were adsorbed on Tenax-TA sampling tubes then thermally desorbed via a homemade split device prior to cryotrapping and analyzed by gas chromatograph with flame ionization detector. All the compounds including the m,p-xylene isomer can be separated completely by a DB-WAX capillary column. Breakthrough volumes of target compounds were measured by photoionization detector under the condition of 30 +/- 3 degrees C and 80 +/- 5 % relative humidity in a concentration level of the twice threshold limit value. Results showed the breakthrough volumes were concentration dependent and influenced by the competitive effect between different compounds. The thermal desorption recovery yield of this method was in the range of 94.8 %similar to 101.2 %. All the compounds can be stored safely within 15 days both in the room and freezing temperature. The developed method was compared well with the current method (charcoal adsorption and solvent extraction) in a real air monitoring at the same sampling place and time. The analyte concentrations are well below the prescribed limits in the test surface coating industry.