Gabriela Pereira da Silva Maciel

Speciation of nitrogen-containing compounds in an unfractionated coal tar sample by comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry.

Comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC×GC/TOFMS) has shown great skill in analyzing complex mixtures such as fossil fuels, especially for compounds at low concentrations. The analysis of N-polyaromatic compounds (NPAC) in coal and crude oil is a great challenge for analytical chemistry due to its environmental and technological importance, and also its diversity of concentration in the matrix. This study is the first report in the applicability of GC×GC/TOFMS for detection of NPAC in a coal tar sample with no fractionation. Normally these compounds are analyzed after sample treatment, making the process expensive and time consuming. However, the higher separation power of GC×GC/TOFMS, compared to 1D-GC, produces cleaner mass spectra in complex samples, which helps in identification of analytes with no pre-fractionation. In this paper, the main objectives were to demonstrate the applicability of GC×GC/TOFMS in the speciation and separation between basic and neutral NPAC from coal tar sample derived from fast pyrolysis, without prior sample fractionation. The methodology used here consisted of chromatographic injection of the diluted sample using a conventional columns set and data analysis by ChromaTOF/Excel™ software. Some basic compounds (pyridines and quinolines) and neutral ones (carbazoles and indoles) were detected with good chromatographic separation and spectral similarity. Tools like spectral deconvolution, extracted ion chromatogram (EIC) and dispersion graphics allowed greater security on the identification and separation of NPAC in this complex sample of coal tar, with no pre-treatment.

Comprehensive two dimensional gas chromatography with fast-quadrupole mass spectrometry detector analysis of polar compounds extracted from the bio-oil from the pyrolysis of sawdust

In this paper it is studied the most polar fractions of bio-oil produced by fast pyrolysis of Lignocel BK40-90 (sawdust from forest timber). The biomass was submitted to the pyrolysis in an existing FCC pilot plant that was adapted for this procedure. The equipment consists of a fluidized bed reactor with nitrogen injection. The unit operates with continuous biomass feeding and continuous solids circulation. The produced bio-oil was submitted to an aqueous alkaline extraction, isolating the acidic compounds that were analyzed by one-dimensional gas chromatography and comprehensive two-dimensional gas chromatography with quadrupole mass spectrometry detection (qMS). One hundred and thirty compounds (mainly phenols and ketones) were tentatively identified in the extract, some of them by the use of retention indexes. The main differences between chromatographic techniques were the substantial increasing in the peak capacity of GC×GC and the resolution of some co-elutions that occurred in GC/qMS. It is also possible to conclude that this extract is rich in important raw materials for the chemical industry and can be used for this end.

Quantification of nitrogen compounds in diesel fuel samples by comprehensive two‐dimensional gas chromatography coupled with quadrupole mass spectrometry

Although several methods for the analysis of nitrogen compounds in diesel fuel have been described in the literature, the demand for rapid, sensitive, and robust analyses has increased in recent years. In this study, a comprehensive two-dimensional gas chromatographic method was developed for the identification and quantification of nitrogen compounds in diesel fuel samples. The quantification was performed using the standard addition method and the analysis was conducted using comprehensive two-dimensional gas chromatography coupled with fast quadrupole mass spectrometry. This study is the first to report quantification of nitrogen compounds in diesel fuel samples using the standard addition method without fractionation. This type of analysis was previously performed using many laborious separation steps, which can lead to errors and losses. The proposed method shows good linearity for target nitrogen compounds evaluated (m-toluidine, 4-ethylaniline, indole, 7-methylindole, 7-ethylindole, carbazole, isoquinoline, 4-methylquinoline, benzo[h]quinolone, and acridine) over a range from 0.05 to 2.0 mg/L, and limits of detection and quantification of <0.06 and 0.16 mg/L, respectively, for all nitrogen compounds studied.

Comprehensive Two-Dimensional Gas Chromatography and Its Application to the Investigation of Pyrolytic Liquids

The chapter presents basic principles of one-dimensional gas chromatography (1D-GC) and comprehensive two-dimensional gas chromatography (GC × GC) related to the main advantages of the two-dimensional technique, as well as its application to the study of organic compounds in liquids derived from coal, mainly through pyrolysis and extraction. It also shows the investigation of compounds contained in bio-oils obtained from biomass through pyrolysis, using GC × GC. Advances in scientific knowledge related to the composition of these complex matrices are shown through different examples of GC × GC analyses, such as the identification of trace compounds that would not be perceived by 1D-GC, organized patterns of elution of structurally related compounds that help their identification, etc. Examples shown make it clear that GC × GC is the technique of choice to elucidate composition of these complex matrices.

Antimicrobial Potential of Bio-Oil for Use in Diesel Oil B10

The aim of this study was to evaluate the antimicrobial activity of bio-oil (obtained by pyrolysis of biomass: soybean oil, eucalyptus sawdust and coffee grounds) added to the blend B10 (diesel and biodiesel). The bio-oil is compatible to diesel oil and it contains promising compounds that can exhibit antimicrobial activity during fuel storage. We evaluated the antimicrobial activity of bio-oil added to diesel oil B10 by determining the minimum inhibitory concentration at different concentrations (0-10%) using oil-deteriorating microorganisms for 10 days at 30 °C. Bio-oil was separated from the aqueous phase by solid phase extraction using ultrapure water and sodium hydroxide. The aqueous phase containing the solubilized compounds of bio-oil was characterized by comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometric detection. Minimum inhibitory concentration in the range of 0.25% to 4% was observed for the tested inocula. The chromatographic analysis of both extracts allowed the identification of several oxygenated compounds, which the majority of the analytes consisted of phenolic compounds, followed by ketones.