Trace levels of formaldehyde in ambient air were collected using an absorbent coated with 2-hydroxymethyl piperidine (2-HMP) which is commercially available as ORBO™ 24 tube. Air samples were passed through the tubes at 200 ml/min under reduced pressure. Formed formaldehyde-oxazolidine derivative (l-aza-8-bicyclo[4.2.0]nonane) was eluted with 500 μl of isooctane containing a decafluorobiphenyl at the concentration of 40 (μg/ml as an internal standard and analyzed with FID-GC. GC analyses were performed using a fused silica capillary column (DB-WAX, 0.32 mm i.d., 30 m length, film thickness: 0.25 μm) under splitless injection mode. The temperature program of GC analyses was as follows: 50°C isothermal for lmin, programming to 220°C at 10°C/min, hold at 220°C for 1 min. Linear calibration was obtained from 0 to 17.5 μg. The accuracy and precision measured as recovery and its relative standard deviation of six replicates at 0.875 μg was 100.2 ± 7.5%. The detection limit was estimated to be 0.23 μg. The method has been used to evaluate levels of formaldehyde in ambient air; formaldehyde was detected at 3.9~15.9 ppb in the samples of an underground parking lot and shopping mall.
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