RESUMO
Analytical conditions for the analysis of 15 carbonyl-DNPH derivatives were optimized and compared by high performance liquid chromatography (HPLC) and rapid resolution liquid chromatography (RRLC). Binary, ternary and quaternary mixtures of acetonitrile, isopropanol, methanol, tetrahydrofuran and water were evaluated under RRLC conditions employing a Zorbax Eclipse Plus C18 (50 mm x 4.6 mm x 1.8 microm) column and a Zorbax Eclipse Plus C18 (50 mm x 2.1 mm x 1.8 microm) column. The optimized conditions obtained employing the two RRLC columns were compared with those obtained using a Supelcosil C18 (250 mm x 4.6 mm x 5 microm; Supelco) that is designed for HPLC separation of DNPH derivatives. Chromatograms run with a Zorbax Eclipse Plus C18 (50 mm x 2.1 mm x 1.8 microm) column and a mobile phase composed of isopropanol, methanol, tetrahydrofuran and water led to the best separation conditions considering reduced analysis time (approximately 6 min per run), solvent consumption rate (approximately 2 mL per run) and resolution of propanone, acrolein and propionaldehyde hydrazones. Quantification limits and linear ranges were adequate for direct application of EPA TO-11 conditions in all sets of RRLC and HPLC conditions. The analytical method was applied in the determination of carbonyl compounds (CCs) in Niterói City, RJ, Brazil in samples that were collected during periods of 2h. Formaldehyde (8.22-9.78 ppbv) predominated in all periods followed by acetaldehyde (1.77-3.99ppbv) and propanone (1.89-3.26 ppbv). Heavy CCs such as butyraldehyde and benzaldehyde were also detected in most samples. Total CCs varied along the studied day. The obtained results showed that RRLC can be applied to CCs determination without any change in the conditions of sample preparation of the Method EPA TO-11.
RESUMO
The levels of 21 polycyclic aromatic hydrocarbons (PAHs) with molecular weights between 128 Da (naphthalene) and 300 Da (coronene) were determined in Terminalia catappa L. (Combretaceae) bark. Tree bark samples were collected in the campus of Oswaldo Cruz Foundation, a green area located in a very intensive traffic area of Rio de Janeiro City, Brazil and about 10 km away from the city center. Samples were submitted to ultrasonic extraction with dichloromethane and analyzed by high-resolution gas chromatography-mass spectrometry. Individual PAH levels varied from 1.23 to 327 ng/g and phenanthrene, fluoranthene and pyrene predominated in all samples. Total PAH levels ranged from 242 to 1640 ng/g with a mean of 628 ng/g. The levels of total PAHs and of total carcinogenic PAHs showed not a clear dependence with tree location and distances to the main routes of that area. No correlation was observed also with PAH levels previously found in total suspended particulate thus indicating that in this area tree bark PAH levels cannot be used to assess their atmospheric levels.