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Acid Water (acid + water)
Selected AbstractsChemInform Abstract: 2-Iodoxybenzoic Acid/Tetraethylammonium Bromide/Water: An Efficient Combination for Oxidative Cleavage of Acetals.CHEMINFORM, Issue 31 2009Chutima Kuhakarn Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Quantitative determination of haloperidol in tablets by high performance thin-layer chromatographyJOURNAL OF SEPARATION SCIENCE, JSS, Issue 5 2007Sigrid Mennickent Abstract A densitometric high performance thin-layer chromatography (HPTLC) method was developed and validated for the quantitative analysis of haloperidol in tablets. Chromatographic separation was achieved on precoated silica gel F 254 HPTLC plates using a mixture of acetone/chloroform/n -butanol/acetic acid glacial/water (5:10:10:2.5:2.5 v/v/v/v/v) as the mobile phase. Quantitative analysis was carried out at a wavelength of 254 nm. The method was linear in the 10,100 ng/,L range, with a determination coefficient of 0.999. The coefficients of variation for precision were not higher than 2.35%. The detection limit was 0.89 ng/,L, and the quantification limit was 2.71 ng/,L. The accuracy ranged from 97.76 to 100.33%, with a CV not higher than 4.50%. This method was successfully applied to quantify haloperidol in real pharmaceutical samples, including the comparison with HPLC measurements. The method was fast, specific, with a good precision and accuracy for the quantitative determination of haloperidol in tablets. [source] Consumer body composition and community structure in a stream is altered by pHFRESHWATER BIOLOGY, Issue 3 2010A. LARRAÑAGA Summary 1.,Low pH inhibits microbial conditioning of leaf-litter, which forms the principal energy input to many headwater streams. This reduces food quality and availability for the shredder assemblage, thereby creating a potential bottleneck in the flux of energy and biomass through acidified food webs. 2.,We explored the consequences of acidity on the well-characterised community of Broadstone Stream in southeast England, by quantifying the physiological condition (protein and lipid content) of three dominant shredder species (Leuctra nigra, L. hippopus and Nemurella pictetii) and relating this to changes in the numerical abundance and biomass of invertebrates across a longitudinal pH gradient (5.3,6.5). 3.,Total taxon richness increased with pH, as did shredder diversity. The acid-tolerant stonefly, L. nigra, exhibited a positive correlation between pH and protein content, but its abundance was suppressed in the less acid reaches. These results suggest that the impacts of environmental stressors might be manifested differently at the population (i.e. numerical and biomass abundance) versus the physiological (i.e. protein content of individuals) levels of organisation. Body composition of L. hippopus and N. pictetii did not exhibit any significant relationship with stream pH in the field. 4.,The survey data were corroborated with a laboratory rearing experiment using N. pictetii, in which survival rate, growth rate, and protein and lipid content of individuals were measured in stream water of differing pH and acid versus circumneutral microbial conditioning regimes. Acid-conditioned leaves were associated with increased mortality and reduced protein content in consumers' tissues, with acid water also having the latter effect. 5.,Our results suggest that biochemical constraints within key taxa might create energy flux bottlenecks in detrital-based food webs, and that this could ultimately determine the productivity of the entire system. Hence assays of the body composition of macroinvertebrates could be an effective new tool that complements population level studies of the impacts of stressors in fresh waters. [source] Determination of aminoglycoside and macrolide antibiotics in meat by pressurized liquid extraction and LC-ESI-MSJOURNAL OF SEPARATION SCIENCE, JSS, Issue 4-5 2010Houda Berrada Abstract A simple method for the simultaneous determination of dihydrostreptomycin, spectinomycin, spiramycin, streptomycin, tilmicosin, and tylosin in meat has been developed using pressurized liquid extraction and LC-triple quadrupole MS (LC-ESI-MS/MS). The pressurized liquid extraction operational parameters were optimized and no protein precipitating and fat removing steps were required. A gradient HPLC separation was developed with ion-pair mobile phases consisting of aqueous 1,mM heptafluorobutyric acid water and methanol. Protonated molecules were used as precursor ions for CID. Data acquisition under MS/MS was achieved by applying multiple reaction monitoring of three fragment ion transitions to provide a high degree of sensitivity and specificity. Dirithromycin and sisomycin were selected as internal standards. A validation study was conducted for these antibiotics in poultry meat samples. All selected compounds could be detected (monitoring ions by multiple reaction monitoring) in meat samples at amounts below the regulatory level of concern. Using the internal standards, pressurized liquid extraction recovery rates were from 70 to 96% (RSD 12,25%). LC-ESI-MS/MS method detection limits of the selected antibiotics were 1,6,,g/kg. Good method reproducibility was found by intra- and inter-day precisions at maximum residue level, yielding the RSDs less than 15 and 16%, respectively. [source] Identification of key metabolites of tectorigenin in rat urine by HPLC-MSnBIOMEDICAL CHROMATOGRAPHY, Issue 2 2009Wei-Dong Zhang Abstract This is a report about the identification of key metabolites of tectorigenin in rat urine using high-performance liquid chromatography,electrospray ionization ion trap tandem mass spectrometric method (HPLC-ESI-MSn). Six healthy rats were administered a single dose (80 mg/kg) of tectorigenin by oral gavage. Urine was sampled for 0,24 h and centrifuged at 12,000 rpm for 10 min to obtain the supernatants, then the supernatants were purified by solid-phase extraction with a C18 cartridge. The chromatographic separation was carried out on a reversed-phase C18 column with a gradient elution program whereas acetonitrile,0.1% formic acid water was used as mobile phase. Mass spectra were acquired in negative ionization mode and a data-dependant scan was used for the identification of the key metabolites of tectorigenin in the urine samples. As a result, four phase II metabolites and the parent drug tectorigenin were found and identified in rat urine for the first time. Copyright © 2008 John Wiley & Sons, Ltd. [source] | ||||||||||