Seasonal variations in ambient atmospheric levels of formaldehyde and acetaldehyde

A simple technique is described for determining ambient atmospheric levels of formaldehyde and acetaldehyde by using impinger collection in acidified 2,4-dinitrophenyl-hydrazine/acetonitrile solution and direct high-pressure liquid chromatography with UV absorbance detection of the corresponding phenylhydrazone solution on reversed-phase columns. A limit of detection of approx. 1 ppb for 1-h impinger collections is obtained. Data from a coastal NE US site show no discernible diurnal trends, but strong seasonal variations in the levels of both aldehydes are observed, with summer maxima and winter minima. Formaldehyde/acetaldehyde ratios are relatively high (>4) in winter and spring and low (<2) in summer and fall.