A new method for dimethylamine determination in air is reported. The proposed assay is based on the employment of C18-packed solid phase extraction cartridges for sampling. The retained amine is then derivatized inside the cartridges with the reagent 1,2-naphthoquinone-4-sulfonate. By observing the coloured area of the cartridge, a semiquantitative estimation of the amine can be made. It was also possible to distinguish between primary and secondary amines by visual inspection. Quantitative tests entailed desorption from the cartridges of the derivatives formed, and measurement of the absorbance of the collected extracts. The selected conditions were applied to quantify dimethylamine up to 100 microg, the quantification and detection limits being 6.7 and 2 microg, respectively. Satisfactory linearity and precision were obtained. Possible interferences by ammonia, primary amines and diethylamine were tested. The applicability of the procedure was demonstrated by estimating the concentration of dimethylamine in generated and real air samples. The procedure was useful for short-term exposure limit and threshold limit value estimations.