Selective determination of trimethylamine in air by liquid chromatography using solid phase extraction cartridges for sampling

The selective determination of trimethylamine (TMA) in air by liquid chromatography is reported. Sampling is effected by flushing air through C18-packed solid-phase extraction (SPE) cartridges at a flow rate of 15 mL/min for 15 min. Next, TMA is desorbed from the cartridges and injected into the chromatographic system. The analyte is then selectively retained on a precolumn (20 mm×2.1 mm i.d., packed with 30 μm, Hypersil C18 phase), and derivatized on-line by injecting 9-fluorenylmethyl chloroformate (FMOC). Finally, the TMA-FMOC derivative is transferred to the analytical column (125 mm×4 mm i.d., LiChrospher 100 RP18, 5 μm), and monitored at 262 nm. The method was applied to the measurement of TMA in air in the 0.25–2.5 μg interval (equivalent to concentrations of TMA of 1.1–11 mg/m3), providing good linearity, reproducibility and accuracy. The mean recovery of TMA was (96±7%) (n=12), and the limit of detection was 0.05 μg. The proposed procedure allows the selective determination of TMA in the presence of other primary and secondary short-chain aliphatic amines.