Evaluation of C18 adsorbent cartridges for sampling and derivatization of primary amines in air

The sampling efficiency of C18 solid-phase extraction cartridges was investigated for methylamine, ethylamine, propylamine, butylamine and pentylamine, in air. Determination of these analytes was based on derivatization with o-phthaldialdehyde–N-acetylcysteine (OPA–NAC) on the solid support and fluorescence detection at (lambda)excitation=330 nm and (lambda)emission=440 nm of the eluted derivatives. The calibration model derived from aqueous standards was statistically comparable with the calibration model for air standards. Aqueous amines can be used as standards. The method was useful for calculating short-term exposure limits (STEL). A sampling time of 15 min at 30 ml min^-1 was employed. Good recoveries for amines alone and their mixtures were obtained from air and water samples, 98(plus-minus)14 and 97(plus-minus)12% (mean value(plus-minus)standard deviation), respectively. Recovery values were independent of amine concentration. The detection limits varied between 0.16 and 0.52 (mu)g per sample (0.35 and 1.18 mg m^-3, respectively) and the calibration graphs were linear in the range 0.5–2 (mu)g per sample except for pentylamine, which was 1.5–5 (mu)g per sample. The utility of the method was demonstrated for the estimation of methylamine in two generated air samples.