Sampling and quantitation of lipids in aerosols from the remote marine atmosphere

A procedure is described for the determination of organic compounds in aerosols and rain from the remote marine atmosphere. Five classes of naturally occuring lipids (n-alkanes, was esters, fatty alcohols, sterols, and fatty acids) were quantified in the samples. Air samples (4000–10 000 m³) were collected on glass-fiber filters under authomatic control. Rain samples (1–5 l) were collected on an event basis. Filter and rain samples were extracted with dichloromethane and the extracts were fractionated into discrete chemical classes by adsorption chromatography with silica gel. The fractions were derivatized (if necessary) and quantified by high-resolution glass-capillary gas chromatography (HRGC) and HRGC/mass spectrometry. A second filter extraction was required for quantitation of fatty acid salts. On-column injection of the fractions provided identification and quantification of a wide range of homologs within each compound class: C₁₅–C₄₄ for n-alkanes, C₃₆–C₆₂ for was esters, and C₁₃–C₃₆ for fatty alcohols and fatty acids. Internal standards were used to quantify recoveries and concentratins. Mean recoveries relative to the internal standares were 96.5% for C₁₅–C₃₆ n-alkanes, 96.4% for C₂₀–C₃₀ n-fatty acids, 92.5% for C₁₄–C₃₀ n-fatty alcohols and 93.3% for cholesterol. The procedural blanks for the remote marine aerosol samples allow detection limits of 0.1–1.0 pg m^?3 for most compounds. These values are lower than any other method used at coastal marine, rural or suburban sampling locations.