Search

Plants like cotton, hemp and flax can be: indicators of heavy metals pollution ; used as bioadsorbers or used for processing in textile industry. The importance of their heavy metal content becomes significant in their second stage of usage – when they are coming to direct and prolonged contact with the human skin causing health problems, as well as at the end of their existence – when they are disposed to the environment as waste materials causing environmental pollution. This global picture emphasizes the importance of controlling the metal content in cellulosic natural fibers. Therefore the scope of this work was to investigate the heavy metal content of many different cellulosic fibers in order to estimate if such materials could be used as indicators of pollution. The analytical procedures applied for monitoring of metals were inductively coupled plasma optical emission spectrometry (ICP-OES) which followed digestion (dry ashing, open-vessel digestion and microwave digestion) and extraction (liquid/solid extraction, ultrasonic extraction and microwave extraction) protocols. All extraction experiments were designed and optimized by Design Expert software. The developed analytical procedures were successfully applied on textile fibers as well as on textile materials. Obtained results have shown that cellulosic natural fibers are very suitable to be applied as indicators of environmental pollution or as bio-adsorbers.

Introduction Conventional extraction methods (CE) often demand longer extraction time, greater use of solvent and carry the risk of thermal degradation of biologically active compounds. Microwave assisted extraction (MAE) can result in a yield increase in shorter time at the same temperature using less solvent. The influence of solvent, microwave power, temperature and time of MAE on the concentration of total phenols (TP) of dry wild sage was investigated and compared with CE. Methodology Wild sage was dried for a week and stored in paper bags at room temperature. Polyphenols were extracted using water, 30% ethanol and 30% acetone with reflux at 60ºC for 30 minutes. MAE was carried out using the same solvents, varying temperature, extraction time and microwave power. TP were determined using Folin-Ciocalteu method. Results and discussion The amount of TP in extracts obtained by MAE at 500W for 10 minutes at different temperatures (30, 50, 60 and 80ºC) was highest at 80ºC for all solvents. In the second phase extraction was carried out at 80ºC, 500W for 2, 3, 5, 7, 9 and 10 minutes. The amount of TP increased with longer extraction time giving the highest yield at 9 minutes for all solvents. In the third phase influence of the microwave power (500, 700, 800W) on extraction yield was researched while extraction time and temperature were constant. Microwave power higher then 500W did not increase significantly the amount of TP. The influence of extraction solvent was the same at all phases of MAE and CE with ethanol and acetone both producing higher extraction yield then water. When compared, the amount of TP in all extracts obtained by MAE at optimal conditions was higher then in those obtained by CE. Conclusions MAE results in higher extraction yield in shorter time then CE. Based on the amount of TP ethanol and acetone are equally effective as extraction solvents and optimal conditions for MAE of sage polyphenols are: temperature 80ºC, extraction time 9 minutes and microwave power 500W

152 f. Submitted by Ana Hilda Fonseca (anahilda@ufba.br) on 2013-04-04T15:44:44Z No. of bitstreams: 1 TESE COMPLETA_SONILDA TEIXEIRA.pdf: 3246757 bytes, checksum: c41c8741042ef35b54690019e768753b (MD5) Approved for entry into archive by Ana Hilda Fonseca(anahilda@ufba.br) on 2013-05-09T16:28:03Z (GMT) No. of bitstreams: 1 TESE COMPLETA_SONILDA TEIXEIRA.pdf: 3246757 bytes, checksum: c41c8741042ef35b54690019e768753b (MD5) Made available in DSpace on 2013-05-09T16:28:03Z (GMT). No. of bitstreams: 1 TESE COMPLETA_SONILDA TEIXEIRA.pdf: 3246757 bytes, checksum: c41c8741042ef35b54690019e768753b (MD5) Previous issue date: 2009 CAPES Amostras de material particulado (PM10) foram coletadas no Recôncavo Baiano (RB) e em uma estação controle (Arembepe), de Agosto de 2007 a Abril de 2008, utilizando um amostrador de grandes volumes. Foram medidas as concentrações dos 16 HPAs classificados como poluentes prioritários pela Agência de Proteção Ambiental dos Estados Unidos (US-EPA), em duas campanhas de amostragem intensivas, nas estações chuvosa e seca, pelo período de 24 h durante 5-6 dias consecutivos, nos três sítios localizados na parte norte e nordeste da Baía de Todos os Santos (BTS) e em Arembepe (litoral norte da Bahia) tomado como sítio controle. Os filtros de fibra de vidro foram extraídos por microondas (MAE) utilizando um protocolo otimizado no qual a extração ocorreu em 10 min e consumiu 20 mL de DCM/acetona (1:1) antes da análise por cromatografia a gás/espectrometria de massas com detector de massas (GC/MS/MS). O somatório das concentrações médias dos 16 HPAs variou de 0,036 ng m-3 (Arembepe) a 108 ng m-3 (próximo a refinaria de petróleo e indústria de eletrodos de Carbono), apresentando uma variação sazonal (razão inverno/verão) na faixa de 0,2-306. Os HPAs potencialmente carcinogênicos representaram 53-74% da concentração total nos sítios do RB. Os HPAs predominantes foram os de alta massa molecular, do Fluoranteno ao Benzo(ghi)perileno, representando 90-99 % do total de HPAs no RB. Em Candeias as concentrações elevadas encontradas no inverno foram provavelmente causadas por emissões locais de fontes estacionárias. Para facilitar a identificação das fontes de HPAs no PM10 foi aplicada a análise de componentes principais (PCA) juntamente com o estudo das razões diagnósticas entre HPAs específicos. Na região estudada as emissões veiculares e industriais foram as principais contribuintes para os HPAs associados ao PM10. As concentrações de benzo(a)pireno equivalente (BaPeq) foram estimadas usando a relação de fatores de equivalência tóxica (TEFs) com valores de 0,1 a 22 ng m-3. Concentrações elevadas de BaPeq para os HPAs de 5 a 6 anéis no ar ambiente alertam para uma situação de aumento de riscos para a saúde humana e para a qualidade ambiental na região do RB, principalmente em Candeias e Madre de Deus Salvador

A new method has been developed for the extraction of capsaicinoids (nordihydrocapsaicin, capsaicin, dihydrocapsaicin, homocapsaicin and homodihydrocapsaicin) in peppers employing microwave-assisted extraction. The parameters studied are: extraction solvent (methanol, ethanol, acetone, ethyl acetate and water), temperature (50-200 degrees C), sample quantity (0.1-1 g), volume of solvent (15-50 mL) and the extraction time (5-20 min). The results found for the optimum conditions are: 125 degrees C as extraction temperature, 25 mL of solvent, 0.5 g of freshly triturated peppers and extraction for 5 min, employing 100% ethanol as solvent. The capsaicinoids obtained were stable under the optimised extraction conditions. The resulting method presents a high degree of reproducibility (R.S.D.6%).

Hydrotrope solutions provide safe and effective media for the microwave assisted extraction of andrographolide, the major bioactive chemical constituent of plant Andrographis paniculata. Microwave assisted extraction of androgpaholide was carried out by using hydrotropes, sodium benzoate and urea. The objective of this work were to determine the Minimum Hydrotrope Concentration (MHC) and to determine the effectiveness of each hydrotrope with respect to andrographolide at different system powers. The microwave assisted extractions of andrographolide were carried out at different concentration of hydrotropes (0.2-3M) and different system powers (39.9 and 119.7 Watt). Twenty grams of Andrographis paniculata dried powder were added to 200 ml of hydrotrope solutions and extracted in a microwave extractor for 15 minutes. The research result showed that the percentage of the microwave assisted extraction of andrographolide by using sodium benzoate and urea were up to 10.9% and 1.05% respectively. The Minimum Hydrotrope Concentration and the effectiveness of hydrotropes that was measured in term of Setschenow constant (K s ) were reported for two hydrotropes used in this study.

Chromatography and extraction techniques, and also chemiluminescence have been utilized to develop new rapid and informative tools in the evaluation of long-term properties and environmental effects of polymeric materials. Methods were developed for classification of materials and for early and rapid degradation detection. Degradable polyethylene films were classified on the basis of their incorporated prooxidant systems using chromatographic fingerprinting of carboxylic acids, the dominating type of degradation product. The fingerprints were also shown to be useful for prediction of the degradation states and evaluation of the degradation mechanisms. Classification and prediction models were obtained by Multivariate Data Analysis, where the diacids were grouped according to both their type of prooxidant system and their state of degradation. The use of total luminescence intensity (TLI) measurements was also investigated as a means of classifying films and for the early detection of degradation. Comparisons were carried out with common techniques, e.g. FTIR and DSC, after both thermal and UV oxidation. TLI gave an earlier detection of degradation and was more sensitive than carbonyl index and crystallinity measurements to relative differences in degradation between the materials. It furthermore offered complementary information regarding changes in activation energies during the course of the degradation. The results were compared with the chromatographic fingerprints. A new way to evaluate the low temperature long-term stabilisation efficiency of antioxidants was investigated. A prooxidant was used to obtain catalytic oxidation, instead of using thermal acceleration, to evaluate the stabilisation efficiency of antioxidants at low temperatures but still during reasonably short aging times. Comparisons were made between polypropylene films stabilised with primary antioxidants (Irganox 1076, Irganox 1010 and α-tocopherol) with and without the prooxidant manganese stearate at different temperatures. The relative efficiencies of the antioxidants obtained under prooxidant acceleration test correlated better than thermal acceleration test with the results of a long-term low temperature test. Additives in plastic packaging materials may affect the environment after migration from the packaging to e.g. their contents, especially if they consist of organic aqueous solutions or oils. The use of Solid-Phase Microextraction (SPME) for the specific task of extraction from an organic aqueous solution such as a simulated food or pharmaceutical solution consisting of 10 vol-% ethanol in water was investigated. Methods were developed and evaluated for extraction both with direct sampling and with headspace sampling. If the extraction method and temperature were selected to suit the concentration levels of the analytes, it was possible to quantify several degradation products simultaneously. Comparisons made with Solid Phase Extraction showed the advantage of SPME for this purpose. QC 20100929

A procedure to extract polycyclic aromatic hydrocarbons (PAHs) from a contaminated river sediment is discussed; this combines short extraction times obtained by microwave energy with the peculiar solvent capability of aqueous micellar solutions. The technique, named microwave-assisted micellar extraction (MAME), was tested for the extraction of 11 PAHs from a spiked river sediment using polyoxyethylene (23) dodecyl ether (Brij 35), polyoxyethylene (10) dodecyl ether (C 12 E 10 ) or cetyl trimethylammonium bromide (CTAB). Different temperatures and extraction times were explored to establish whether this method has merit. Comparative measurements were made using sonication and Soxhlet extraction with acetone-hexane. Generally, Soxhlet extraction was revealed to be the most effective method to extract the PAHs from the solid matrix, with percent of recovery ranging from 92% to 102%. Nevertheless, high recoveries were also achieved by MAME using C 12 E 10 ; in fact, with only the exception of indeno[1,2,3- c...

Experimental data are presented for the first time in support of a theoretical model of band broadening proposed by Blumberg (1997). This model addresses the effects of the compressibility of the mobile phase in gas chromatography and presents an equation derived from only two mutually independent variables. Solutions of decane and tridecane in hexane were analyzed at pressures ranging from 15 to 150 psi. Six different columns were used that varied in length, internal diameter and film thickness. Theoretical plate heights were obtained from this data and plotted versus the average linear carrier gas velocity (Golay type plots). These plots showed that at high pressures the Blumberg model fit the experimental data statistically significantly better than the earlier model proposed by Golay. The Blumberg model also accurately predicts the relationship between the optimum linear carrier gas velocity and the temperature. The second part of this work explores the scope and limitations of fast temperature programming in the fast GC analyses of various sample types. These samples included polycyclic aromatic hydrocarbons (PAHs), hydrocarbons and food samples. Programming rates of up to 1200° C/min were used. These fast programming rates were obtained by using "flash"â ¢ temperature programming, controlled by resistive heating of a metal tube that enclosed a capillary column. The precision of peak data was found to be good, less than 5% for peak areas and 4% for retention times. However, a slight, but statistically significant decrease in peak areas was seen above programming rates of 240° C/min. Microwave assisted extraction (MAE) was used to extract 2,6-di-(tert-butyl)-4-methylphenol, BHT, from chewing gum and breakfast cereal. The extraction was followed by a fast GC analysis (less than 4 minutes) using "flash"â ¢ temperature programming. MAE reduced the sample preparation time, from hours to minutes, and consequently reduced, the total analysis time. Extraction times longer than 5 minutes gave decreased recoveries of BHT. Ph. D.

The effects of solvent-to-feed (S) and temperature (T) on the kinetics and thermodynamics of the microwave assisted extraction (MAE) of flavonoids from dried fruits of Phyllanthus emblica using water as solvent have been studied. The flavonoid concentration - time data was analyzed using second order and diffusion models. Both the temperature and solvent-to-feed ratio influenced the initial extraction rate and equilibrium concentration. Biot numbers were found to be greater than 50, implying that the internal mass transfer was the rate controlling step in MAE. The composition of extracts obtained using MAE and conventional extraction was similar. However, the effective diffusion coefficients were doubled in MAE when compared to conventional extraction. An empirical correlation was developed to predict the kinetics of MAE as a function of solvent-to-feed ratio and temperature. The study will be of interest to food and pharmaceutical industries.

To highlight the shortcomings in conventional methods of extraction, this study investigates the efficacy of Microwave Assisted Extraction (MAE) toward bioactive compound recovery from pharmaceutically-significant medicinal plants, Adathoda vasica and Cymbopogon citratus. Initially, the microwave (MW) drying behavior of the plant leaves was investigated at different sample loadings, MW power and drying time. Kinetics was analyzed through empirical modeling of drying data against 10 conventional thin-layer drying equations that were further improvised through the incorporation of Arrhenius, exponential and linear-type expressions. 81 semi-empirical Midilli equations were derived and subjected to non-linear regression to arrive at the characteristic drying equations. Bioactive compounds recovery from the leaves was examined under various parameters through a comparative approach that studied MAE against Soxhlet extraction. MAE of A. vasica reported similar yields although drastic reduction in extraction time (210 s) as against the average time of 10 h in the Soxhlet apparatus. Extract yield for MAE of C. citratus was higher than the conventional process with optimal parameters determined to be 20 g sample load, 1:20 sample/solvent ratio, extraction time of 150 s and 300 W output power. Scanning Electron Microscopy and Fourier Transform Infrared Spectroscopy were performed to depict changes in internal leaf morphology.

This paper presents a simple, ecofriendly, robust and inexpensive method for the preparation of radish (Raphanus sativus) and spinach (Spinacia oleracea) extracts that are destined to be tested as green corrosion inhibitors. The obtained extracts proved to be stable in the corrosive media as no significant changes could be observed on the HPLC profile, nor on the UV and FTIR spectra of the extracts solubilized in either the acidic, alkaline or saline media.

This work characterized South African coal for metals, organic and inorganic sulfur compounds. Microwave assisted extraction (MAE) followed by Inductively Coupled Plasma–Optical Emission Spectrometry (ICP-OES) were used for extraction, identification and quantification of inorganic, organic, total sulfur forms as well as selected metals related to the presence of sulfur in coal. The total sulfur content was also determined in coal by direct elemental analysis for carbon, hydrogen, nitrogen and sulfur. Thiophene organic sulfur compounds in coal were extracted with ultrasonication system followed by identification and quantification using gas chromatography and flame ionization detector. The ultrasonication extraction system was optimized for the extraction organic solvent, the extraction time and influence of sample concentration. Microwave assisted extraction followed by ICP-OES gave an average of 8758, 4500, 3600 and 600 mg kg–1 for total sulfur, pyrite sulfur, organic sulfur and sulfate sulfur, respectively. Pyrite and organic sulfur forms were found to compete for the largest amounts in coal samples. The total sulfur content in South African coal was found to be less than 20 000 mg kg–1 which suggests that the coal may be of low sulfur content compared to others in the world. The mean percentages of carbon, hydrogen, nitrogen and sulfur in coal samples was 66.20, 2.98, 1.15 and 1.11 confirming that it is of bituminous rank. The concentration levels of selected metals were found in this decreasing order; Na>Ca>Fe>Mg>K>Ba>Mn>Cr>Pb> Zn>Cu>As>Co>Sb>Hg. Thiophene organic sulfur compounds were best extracted with dichloromethane with five sequential extractions of 15 min each. Recovery of extraction from spiked concentration ranged from 40 % to 70 % depending on the individual compound. More volatile organic sulfur compounds showed lowest recovery especially at low spiked concentrations. 2-methyl thiophene was the only compound identified in all coal samples. The concentration of thiophene sulfur compounds ranged from about 4–16 mg kg–1. Dibenzothiophene was found with the highest concentration (15.5 mg kg–1) while 2-ethyl thiophene was found with the lowest concentration.Keywords: Coal, sulfur, metals, microwave assisted extraction, and ultrasound assisted extraction, inductively coupled plasma optical emission spectrometry, gas chromatography