Evaluation of Aliphatic Hydrocarbons in Surface Sediments of Lagoa Mirim (RS, Brazil).

In this study, the hydrocarbons (HCs) levels in sediments from Lagoa Mirim, situated in the south of Brazil, were verified. The methodology brought together stages of pre-sonification, soxhlet extraction, and determination by gas chromatography coupled with mass spectrometry (GC/MS). Ten sample points were evaluated where ∑n-alkanes varied between 1.46 µg kg-1 ± 4.0% and 10.10 µg kg-1 ± 17.6%. Diagnostic indexes were calculated, being: Carbon Preferential Index (CPI), terrestrial/aquatic ratio (TAR), unresolved complex mixture (UCM), UCM/∑n-alkanes ratio, and n-alkane ratio with Low molecular weight hydrocarbon and High molecular weight hydrocarbons (HMW/LMW). In general, the results of this study indicate a low anthropogenic impact in the environment.

Estudo comparativo dos bio-óleos obtidos por pirólises rápida e lenta do caroço de pêssego / Comparative study of bio-oils obtained by fast and slow pyrolysis of peach stone

RESUMO O processamento de pêssego em conserva gera o caroço como resíduo agroindustrial de difícil destinação. Assim, a técnica de pirólise do endocarpo lenhoso é um eficiente tratamento para conversão da biomassa em produtos com valor agregado. Entre os produtos, o bio-óleo é composto de duas fases imiscíveis (orgânica e aquosa), com potencial para suprir a produção de produtos químicos em diferentes ramos industriais. O objetivo deste estudo foi obter e avaliar a constituição da fase orgânica dos bio-óleos com base nas pirólises rápida (reator de quartzo) e lenta (reator de aço inox) do endocarpo lenhoso, ambos de leito fixo a 700°C evidenciando assim a influência dos processos na constituição dos bio-óleos obtidos. As frações líquidas foram derivatizadas com N-metil-N-trimetilsililtrifluoracetamida para posterior caracterização em cromatografia gasosa acoplada à espectrometria de massas. Pela metodologia empregada, detectaram-se nas fases orgânicas dos bio-óleos da pirólise rápida e lenta um total de 59 e 41 compostos, respectivamente; destes, os fenóis são majoritários com 59,9% e 67,2%, em massa, em que os núcleos metoxifenol (rápida) e os alquilfenóis (lenta) são os compostos predominantes. Conclui-se que a etapa de derivatização e a técnica de cromatografia gasosa acoplada à espectrometria de massas foram satisfatórias para a caracterização qualitativa e semiquantitativa dos bio-óleos, os quais mostraram potencial de utilização como fonte de produtos químicos e beneficiamento no reaproveitamento de resíduos.

ABSTRACT The processing of pickled peaches generates the peach stone as an agro-industrial residue that is difficult to dispose of. Thus, the woody endocarp pyrolysis technique is an efficient treatment for converting biomass into value-added products. Among the products, bio-oil is composed of two immiscible phases (organic and aqueous), with potential to supply the production of chemical products in different industrial sectors. The objective of this study was to obtain and evaluate the constitution of the organic phase of the bio-oils based on the fast (quartz reactor) and slow (stainless steel reactor) pyrolysis of the woody endocarp, both with fixed bed at 700°C, thus evidencing the influence of processes in the constitution of the obtained bio-oils. As liquid fractions, they were derived with N-methyl-N-trimethylsilyltrifluoracetamide for further characterization in gas chromatography coupled with mass spectrometry. Through the methodology employed, a total of 59 and 41 compounds were detected in the organic phases of the fast and slow pyrolysis bio-oils, respectively; Phenols are the majority, with 59.9 and 67.2% by weight, where the methoxyphenol (fast) and cresols (slow) are the predominant compounds. It is concluded that the derivatization stage and the gas chromatography/mass spectrometry technique were satisfactory for the qualitative and semi-quantitative characterization of bio-oils, which they can potentially use as a source of chemical products and to benefit from reuse of residue.

Determination of hydrocarbons transported by urban runoff in sediments of São Gonçalo Channel (Pelotas - RS, Brazil).

A high concentration of hydrocarbons in the environment is indicative of pollution. To evaluate the effect of hydrocarbons transported by urban runoff, the present study analyzed total petroleum hydrocarbons (TPHs), aliphatic hydrocarbons (AHs), unresolved complex mixture (UCM), and n-alkanes of the sediments of the canal that cross the urban area of Pelotas, Rio Grande do Sul, Brazil. The carbon preference index (CPI), terrigenous/aquatic ratio (TAR), and pristane/phytane ratio were determined. The TPH content ranged from 177,043.7µg·kg-1±13.4% to 5,892,667.0µg·kg-1±5.9%. The total aliphatic content ranged from 116,268.8µg·kg-1±11.1% to 2,393,592.6µg·kg-1±7.7%, indicating chronic contamination of n-alkanes petrogenic and biogenic sources. The levels of hydrocarbons (TPH, AHs, and n-alkanes) were considered relatively high, confirming the effect of urban runoff on the drainage system of cities and their consequent effect on the estuarine region of Patos Lagoon and other water resources.

Determination of volatile and non-volatile nickel and vanadium compounds in crude oil using electrothermal atomic absorption spectrometry after oil fractionation into saturates, aromatics, resins and asphaltenes.

In recent work, it has been shown that electrothermal atomic absorption spectrometry (ET AAS) can be used to differentiate between volatile and non-volatile nickel and vanadium compounds in crude oil. In the present work, the distribution of these two groups of compounds over different fractions of crude oil was investigated. For this purpose two crude oil samples were separated in two steps: firstly, the asphaltenes were precipitated with n-heptane, and secondly, the maltenes were loaded on a silica column and eluted with solvents of increasing polarity. The four fractions of maltenes eluted from silica column were: F1, saturated and light aromatics; F2, polyaromatics; F3, resins; and F4, polar compounds. Fractions F1 and F2 were further investigated using gas chromatography, and all fractions were characterized by CHN analysis, confirming the increase of aromatics in the fractions 2, 3, 4 and asphaltenes. For the determination of Ni and V by ET AAS, oil-in-water emulsions were prepared. The speciation analysis was carried out measuring without chemical modifier (stable compounds) and with 20 microg palladium (total Ni and V) and the volatile fraction was calculated by difference. The limits of detection were 0.02 microg g(-1) and 0.06 microg g(-1), for Ni and V, respectively, based on an emulsion of 2g of oil in 10 mL. The volatile species of Ni and V were associated with fractions F3 and F4, while only thermally stable Ni and V was precipitated in part together with the asphaltenes.

Method of determination of nitrosamines in sausages by CO2 supercritical fluid extraction (SFE) and micellar electrokinetic chromatography (MEKC).

In this paper, the use of supercritical fluid extraction (SFE) and micellar electrokinetic capillary chromatography (MEKC) is proposed for the complete analysis of volatile nitrosamines in sausages. The extraction fluid used was CO2 and variables such as density, temperature of thimbles, extraction time, modifier, fluid flow, and kind of traps were investigated. Several experiments were carried out to obtain the most favorable conditions for analysis of volatile nitrosamines in sausages. The recoveries ranged from 21 to 82% for the five nitrosamines studied. The optimal condition of extraction was 0.2 g of sample fortified with 10 mg/kg, using dynamic extraction during 20 min and with adsorbent Florisil in the trap. The solvent selected for the elution of the analytes was methanol.

Determination of nitrosamines in preserved sausages by solid-phase extraction-micellar electrokinetic chromatography.

A new methodology for extraction, pre-concentration and analysis of nitrosamines in meat derived products was developed. The samples (canned sausages) were distilled in vacuum steam and the nitrosamines were pre-concentrated by solid-phase extraction with active carbon. Then, micellar electrokinetic chromatography was used for the separation and determination of the different nitrosamines contained in a real sample and gas chromatography with mass spectrometry detection was used as the confirmation technique. The method allowed the determination of nitrosamine compounds at trace levels with relative standard deviation ranging from 4.0 to 22%.