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Solvent Consumption (solvent + consumption)
Selected AbstractsChemical composition of mate tea leaves (Ilex paraguariensis): A study of extraction methodsJOURNAL OF SEPARATION SCIENCE, JSS, Issue 18 2006Rosângela Assis Jacques Abstract The objective of this work was to investigate the extraction of Ilex paraguariensis leaves by means of three extraction techniques: pressurized liquid extraction (PLE, also called accelerated solvent extraction , ASE), maceration, and sonication. Samples of mate tea leaves were collected from an experiment conducted under agronomic control at Indústria e Comércio de Erva-Mate Bar,o LTDA, Brazil. Six solvents with increasing polarities (n -hexane, toluene, dichloromethane, ethyl acetate, acetone, and methanol) were used in this investigation. Chemical analysis of the extracts was performed by GC coupled with a mass spectrometer detector. The identification and quantification were accomplished by coinjections of certified standards. The results showed that no significant differences in the qualities of the extracts were noticed regarding the extraction methods. On the other hand, the PLE technique was found to be more effective for the extractions of caffeine, phytol, palmitic, and stearic acid. The use of PLE led to a significant decrease in the total extraction time, amount of solvent consumption, and manipulation of samples compared to maceration and ultrasound-assisted extraction methods. [source] Application of water as a solvent in microwave-assisted extraction for analysis of PCBs and CBzs in fly ashJOURNAL OF SEPARATION SCIENCE, JSS, Issue 6 2005Yifei Sun Abstract Polychlorinated biphenyls (PCBs) and chlorobenzenes (CBzs) are two classes of dioxin precursors formed in municipal solid waste incinerators (MSWIs); they produce negative health effects similar to those of dioxins. Reducing the analytical time required for determining the concentrations of these compounds in MSWIs is important for quickly evaluating their importance and assessing associated health risks. In the present study, water is used as a safe and environmentally friendly solvent in microwave-assisted extraction (MAE) for PCB and CBz analyses. MAE is compared with traditional Soxhlet extraction (SE) to determine the extraction efficiencies. The evaluation of extraction efficiencies shows that MAE has a high extraction efficiency compared with that of SE when water content is lower than 60%. Furthermore, the extraction time and organic solvent consumption are reduced with MAE compared with SE. [source] Application of solid phase microextraction for the determination of soil fumigants in water and soil samplesJOURNAL OF SEPARATION SCIENCE, JSS, Issue 1 2005Sonia Fuster Abstract The potential of solid phase microextraction (SPME) for the determination of the soil fumigants 1,3-dichloropropene (1,3-DCP) and methyl isothiocyanate (MITC) in environmental samples such as soil and water samples has been investigated. Direct immersion SPME followed by GC/ECD/NPD analysis allowed the rapid determination of the two fumigants in water samples, with very little sample manipulation, giving an LOD of 0.5 ,g L,1. Precision, calculated as relative standard deviation (RSD) for six replicates at three concentration levels, was found to be lower than 20% at the concentration levels tested. For the analysis of soil samples, headspace (HS)-SPME combined with GC/ECD/NPD analysis has been applied. Quantification using matrix-matched calibration curves allowed determination of both analytes (MITC and 1-3-DCP) with a LOD of 0.1 ,g kg,1 (RSD <10%) for the two concentration levels assayed (0.02 and 0.2 mg kg,1). The HS-SPME procedure developed in this paper was applied to soil samples from experimental green house plots treated with metham-Na, a soil disinfestation agent that decomposes in soil to MITC. The absence of sample manipulation as well as the low solvent consumption in SPME methodology are among the main advantages of this analytical approach. [source] Simple 2D-HPLC using a monolithic silica column for peptide separationJOURNAL OF SEPARATION SCIENCE, JSS, Issue 10-11 2004Hiroshi Kimura Abstract Separation of peptides by fast and simple two-dimensional (2D)-HPLC was studied using a monolithic silica column as a second-dimension (2nd-D) column. Every fraction from the first column, 5 cm long (2.1 mm ID) packed with polymer-based cation exchange beads, was subjected to separation in the 2nd-D using an octadecylsilylated (C18) monolithic silica column (4.6 mm ID, 2.5 cm). A capillary-type monolithic silica C18 column (0.1 mm ID, 10 cm) was also employed as a 2nd-D column with split flow/injection. Effluent of the first dimension (1st-D) was directly loaded into an injector loop of 2nd-D HPLC. UV and MS detection were successfully carried out at high linear velocity of mobile phase at 2nd-D using flow splitting for the 4.6 mm ID 2nd-D column, or with direct connection of the capillary column to the MS interface. Two-minute fractionation in the 1st-D, 118-second loading, and 2-second injection by the 2nd-D injector, allowed one minute for gradient separation in the 2nd-D, resulting in a maximum peak capacity of about 700 within 40 min. The use of a capillary column in the 2nd-D led to less solvent consumption and better MS detectability compared to a larger-sized column. This kind of fast and simple 2D-HPLC utilizing monolithic silica columns will be useful for the separation of complex mixtures in a short time. [source] Translational and transcriptional analysis of Sulfolobus solfataricus P2 to provide insights into alcohol and ketone utilisationPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 3 2007Poh Kuan Chong Abstract The potential of Sulfolobus solfataricus P2 for alcohol or ketone bioconversion was explored in this study. S. solfataricus was grown in different concentrations (0.1,0.8% w/v) of alcohols or ketones (ethanol, iso-propanol, n -propanol, acetone, phenol and hexanol) in the presence of 0.4% w/v glucose. Consequently, the addition of these alcohols or ketones into the growth media had an inhibitory effect on biomass production, whereby lag times increased and specific growth rates decreased when compared to a glucose control. Complete glucose utilisation was observed in all cultures, although slower rates of glucose consumption were observed in experimental cultures (average of 14.9,mg/L/h compared to 18.9,mg/L/h in the control). On the other hand, incomplete solvent utilisation was observed, with the highest solvent consumption being approximately 51% of the initial concentration in acetone cultures. Translational responses of S. solfataricus towards these alcohols or ketones were then investigated using the isobaric tags for relative and absolute quantitation (iTRAQ) technique. The majority (>80%) of proteins identified and quantified showed no discernable changes in regulation compared to the control. These results, along with those obtained from transcriptional analysis of key genes involved within this catabolic process using quantitative RT-PCR and metabolite analysis, demonstrate successful alcohol or ketone conversion in S. solfataricus. [source] Quantitative screening and matrix effect studies of drug discovery compounds in monkey plasma using fast-gradient liquid chromatography/tandem mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 24 2001Yunsheng Hsieh A higher-throughput bioanalytical method based on fast-gradient (1,min run time) high-performance liquid chromatography (HPLC) coupled with tandem mass spectrometry (MS/MS) was developed for screen-type analyses of plasma samples from early drug discovery studies in support of exploratory pharmacodynamic studies. The HPLC system equipped with minibore column was interfaced with either atmospheric pressure chemical ionization (APCI) or electrospray (ESI) ionization techniques. The matrix ion suppression effect of both quantitative HPLC/MS/MS analyses was compared using the post-column infusion system. The use of the described methods provided advantages such as a shorter chromatographic region of ion suppression, less solvent consumption and shorter run times in comparison with standard analytical column HPLC/MS/MS methods. The analytical results obtained by both HPLC/MS/MS methods were in good agreement (within 15% of error) and displayed a good correlation with the pharmacodynamic outcome. Copyright © 2001 John Wiley & Sons, Ltd. [source] | ||||||||||