Solid-phase extraction of nitro-PAH from aquatic samples and its separation by reverse-phase capillary liquid chromatography

In this work, an analytical methodology to extract 1-nitronaphthalene, 2-nitrofluorene, 9-nitroanthracene, 3-nitrofluoranthene, and 1-nitropyrene aquatic samples is proposed. Capillary liquid chromatography with on-column UV detection (µLC-UV) was employed to separate and quantitate all five nitrated polycyclic aromatic hydrocarbons (nitro-PAH) extracted from water samples. Two different extraction techniques were tested and compared: liquid-liquid extraction (LLE) and solid phase extraction (SPE) with two different sorbents, octadecylsilica (C18) and styrene divinylbenzene (XAD-2) particles. The elution of analytes was tested with both acetonitrile and methylene chloride. The best recovery results were obtained for SPE-C18 extraction with the methylene chloride with values ranging from 76 to 97% with RSD values smaller than 4%. The chromatographic conditions for analysis was carried out using a 250 × 0.3 mm i.d. packed capillary column with 5 µm C18 particles. The elution was isocratic with 65% acetonitrile in water (v/v) as mobile phase with a flow rate of 7 µL min-1. The detection limits due to on-column UV detection (ranging ~3-30 mmol L-1) are limiting for environmental applications, however, they are suited for toxicological studies

Characterization of Adulteration of "Espinheira Santa" ( Maytenus ilicifolia and Maytenus aquifolium, Celastraceae) Hydroalcoholic Extracts with Sorocea bomplandii ( Moraceae) by High-Performance Thin Layer Chromatography

A HPTLC procedure for the characterization of adulteration of " espinheira santa ( Maytenus sp) with Sorocea bomplandii by monitoring their flavonoid content with the aid of diphenylboric reagent, is presented. HPTLC data showed the predominance of higly glycosated quercetin and kaempferol derivatives. The derivated flavonoids were shown to be best markers for distinguishing between authentic and adulterated drug samples, with several advantages over triterpene analysi

Further triterpenes, steroids and furocoumarins from brazilian medicinal plants of dorstenia genus (moraceae)

The hexane-soluble fractions from the rhizomes or from the leaves from five Dorstenia (Moraceae) species (D. bahiensis Kl., D. bryoniifolia Mart ex. Miq., D. carautae C.C.Berg, D. cayapiaa Vell. and D. heringerii Car. & Val) were analysed by HRGC-MS (high-resolution gas chromatography - mass spectrometry). Pentacyclic triterpenes, steroids and furocoumarins were identified. HRGC-MS is shown to be a valuable tool for the analysis of terpenoidal compounds from Dostenia species. These compounds may be related to the folk utilization of Dorstenia species as antiophidicals

HRGC study of sorption and desorption of atrazine, ametryn and metolachlor on Brazilian soils

The sorption and desorption of herbicides ametryn, atrazine and metolachlor were studied in five Brazilian soils with various organic matter contents using high resolution gas chromatography (HRGC). The regression lines generated presented a coefficient of determination > 0.964, which indicates a good fit of the data by the Freundlich equation. Sorption reached an apparent equilibrium in the soils within approximately 6 h. Hysteresis was observed in both sorption and desorption isotherms. Significant correlations were found among sorption of herbicides, organic matter, and cation-exchange capacity. No relationship was found between adsorption of the herbicides (ametryn, atrazine, and metolachlor) and their water solubility, pKa, and molecular mass, since these herbicides do not belong to the same chemical family. On account of this, the relationship between sorption and herbicide properties cited above was established only for s-triazines. The s-triazine adsorption showed a direct relationship with water solubility, pKa and molecular mass of these compounds on the studied soils

Composition of the volatile compounds from Aniba canelilla (H. B. K.) Mez. extracted by CO2 in the supercritical state

The volatile compounds obtained by SFE-CO2 (supercritical fluid extraction utilizing CO2) from the barks of Aniba canelilla (H. B. K.) Mez. (Lauraceae) were analyzed by HRGC-FID (high resolution gas chromatography - flame ionization detector) and HRGC-MS (high resolution gas chromatography -mass spectrometry). Phenylpropanoids and lower amounts of sesquiterpenoids, representing ca. 97% of the total oil, were identified. The main compound, 2-phenylnitroethane, corresponds to 71,12% of the total oil

Evaluation of a simple hyphenated system for flow injection solid-phase pre-concentration and capillary electrophoresis

In this work, the development and evaluation of a hyphenated flow injection-capillary electrophoresis system with on-line pre-concentration is described. Preliminary tests were performed to investigate the influence of flow rates over the analytical signals. Results revealed losses in terms of sensitivity of the FIA-CE system when compared to the conventional CE system. To overcome signal decrease and to make the system more efficient, a lower flow rate was set and an anionic resin column was added to the flow manifold in order to pre-concentrate the analyte. The pre-concentration FIA-CE system presented a sensitivity improvement of about 660% and there was only a small increase of 8% in total peak dispersion. These results have confirmed the great potential of the proposed system for many analytical tasks especially for low concentration samples.Nesse trabalho apresentamos um sistema hifenizado envolvendo as duas técnicas analíticas: eletroforese capilar (CE) e análises por injeção em fluxo (FIA), denominado de FIA-CE. Parâmetros como a influência do fluxo e a natureza do eluente frente ao sistema CE foram avaliados. O sistema demonstrou-se promissor quanto à possibilidade de aplicações em diferentes áreas da química analítica. O aumento da sensibilidade foi da ordem de 660% devido ao emprego de colunas de troca iônica no sistema FIA. Esse resultado comprova o grande potencial do sistema FIA-CE.Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES)CNPqFAPES

Online Extraction Followed by LC-MS/MS Analysis of Lipids in Natural Samples: A Proof-of-Concept Profiling Lecithin in Seeds

Sample preparation is usually a complex and time-consuming procedure, which can directly affect the quality of the analysis. Recent efforts have been made to establish analytical methods involving minimal sample preparation, automatized and performed online with the analytical techniques. Online Extraction coupled with Liquid Chromatography–Mass Spectrometry (OLE–LC–MS) allows a fully connected extraction, separation, and analysis system. In this work, the lecithin profile was investigated in commercial sunflower, almonds, peanuts, and pistachio seeds to demonstrate that the concept of extraction, followed by the online analysis of the extract, could be applied to analyze this class of analytes in such complex solid matrices without a prior off-line solvent extraction step. The extraction phase gradient method was optimized. Two different analytical columns were explored, one being a conventional C18 (50 × 2.1 mm, 1.7 µm SPP) and the other a novel self-packed SIGO-C18ec (100 × 0.5, 5 µm FPP), which resulted in better separation. The analysis repeatability was investigated, and suggestions to improve it were pointed out. A characteristic ion with a m/z of 184, related to lysophosphatidylcholine structure, was used to identify the lecithin compounds. The temperature effect on the chromatograms was also explored. In short, it was found that the OLE–LC–MS approach is suitable for the analysis of lecithin compounds in seeds, being a promising alternative for lipidomics approaches in the near future