No abstract

Polycyclic aromatic hydrocarbons (PAH) are products of incomplete combustion of biomass and fossil fuels, that are produced on a larger scale by anthropogenic sources. Burning sugarcane plantations can be a source of atmospheric PAH in regions where this culture predominates. Campos dos Goytacazes, Brazil, is surrounded by sugarcane crops that still use fire as a facilitating method for the harvesting process. This study aims to evaluate the presence of outdoor and indoor PAH in 10 µm particulate matter (PM10) at one university in Campos dos Goytacazes. PM10 samples were collected from January to November 2018. Samples were extracted using an ultrasonic probe and analyzed by gas chromatography coupled to mass spectrometry (GC-MS). The ideal extraction conditions (3 min; 150 W; 50 mL) were defined by 23 full factorial design. The analysis showed a significant PM10 level increase (23.19 to 34.50 µg m-3 in outdoor, and 15.15 to 31.66 µg m-3 in indoor samples) and higher total PAH concentration in the harvesting season (outdoor: 0.73 ng m-3; indoor 0.52 ng m-3) than in non-harvesting season (outdoor: 0.49 ng m-3; indoor: 0.28 ng m-3), however, average PAH values found in outdoor samples in harvesting season did not show significant difference from non-harvesting season.

h i g h l i g h t sChloride salts contained in crude oil can cause corrosion and encrustation in distillation towers. Chloride concentrations can be obtained via ICP-OES through the analysis of its counterions. The accuracy of the procedure was confirmed through comparison with the results of FAAS. The modified standard test method of ASTM D 6470-99 extraction was compared with microwave-assisted acid digestion. The study demonstrated that Na, Ca, Mg, Sr and Fe were mainly associated with chloride. a b s t r a c tOf the salts present in crude oil, sodium, calcium, magnesium, strontium and iron chlorides are the most abundant and are considered the main cause of corrosion in crude oil refineries. Therefore, the objective of this study was to quantify the main chloride counterions (Na, Ca, Mg, Sr and Fe) using inductively coupled plasma-optical emission spectrometry (ICP-OES) after hot solvent extraction (modified ASTM D 6470-99). The procedure developed in this work allowed samples with different°API values (17.4-30.2) originating from the post-salt to be studied. Under the operational conditions of ICP-OES, robust plasma (Mg II/Mg I > 10 for the axial and radial configurations) was obtained based on evaluation of the ratio of the Mg II/Mg I intensities. Furthermore, yttrium was used as an internal standard, resulting in as little interference with the analytical signal as possible. This procedure achieved detection limits on the order of 0.99 mg L À1 , 0.025 mg L À1 , 0.33 lg L À1 , 0.06 ng L À1 and 0.26 lg L À1 for Na, Ca, Mg, Sr and Fe, respectively. The accuracy of the procedure was confirmed through addition/recovery tests (91-120%) and through comparison with the results obtained with flame atomic absorption spectrometry (FAAS). The modified standard test method of ASTM D 6470-99 extraction was compared with microwaveassisted acid digestion and was found to achieve extractions higher than 92.44% for Na and 81.06% for Sr from two of the analysed extracts. Finally, the chloride concentrations obtained via potentiometric titration and ICP-OES (through the analysis of chloride with its counterions) in the aqueous extract indicated a high correlation between Na, Ca, Mg, Sr and Fe and chloride (105.10%, 99.33% and 102.12% for the evaluated samples).

Formaldehyde levels in the atmosphere is a concern in the indoor and outdoor air and many methods for determining this compound have been developed. The use of 2,4-dinitrophenylhydrazine (DNPH) for...