DETERMINATION OF FORMALDEHYDE IN AIR BY CHEMISORPTION ON GLASS FILTERS IMPREGNATED WITH 2,4-DINITROPHENYLHYDRAZINE USING GAS-CHROMATOGRAPHY WITH THERMIONIC SPECIFIC DETECTION

A capillary gas chromatographic method using thermionic specific detection (GC-TSD) is presented for the determination of formaldehyde in air. Formaldehyde was sampled with the use of standard miniature glass-fibre impregnated with 2,4-dinitrophenylhydrazine (DNPH). The 2,4-dinitrophenylhydrazone derivative formed was desorbed with acetonitrile. When the solution was eluted through a cation-exchange column the excess of reagent was effectively removed. The eluate was then evaporated to dryness and the residue dissolved in toluene containing the internal standard. The detection limit, defined as three times the filter blanks, was estimated to be 300 ng of formaldehyde per filter, corresponding to a detection limit of formaldehyde in air of ca. 10 mug/m3 or ca. 1/60th of the present Swedish threshold limit (TLV) for a 30-min sampling period. The detection limit for the chromatographic system, defined as three times the noise, was 4 pg of formaldehyde. The overall recovery for filters spiked with 600 ng of formaldehyde was 92 +/- 5%. The calibration graph for 1-6 mug of formaldehyde per filter was linear with a correlation coefficient of 0.998.