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 de veloped. The target compounds were adsorbed on Tenax-TA sampling tubes then thermally desorbed via a homemade split device prior to cryotrap ping and analyzed by gas chromatograph with flame ionization detector. All the compounds including the m,p-xylene isomer can be separated co mpletely by a DB-WAX capillary column. Breakthrough volumes of target compounds were measured by photoionization detector under the conditio n of 30 +/- 3 degrees C and 80 +/- 5 % relative humidity in a concentr ation level of the twice threshold limit value. Results showed the bre akthrough volumes were concentration dependent and influenced by the c ompetitive 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 th e room and freezing temperature. The developed method was compared wel l with the current method (charcoal adsorption and solvent extraction) in a real air monitoring at the same sampling place and time. The ana lyte concentrations are well below the prescribed limits in the test s urface coating industry.