Kooperativer Bibliotheksverbund

Berlin Brandenburg

and
and

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
Language
Year
  • 1
    Language: English
    In: Analytical and Bioanalytical Chemistry, 2012, Vol.402(1), pp.519-527
    Description: A cost-effective and low solvent consumption method, based on the matrix solid-phase dispersion (MSPD) technique, for the determination of six benzotriazole UV absorbers in sediments is presented. Sieved samples (0.5 g) were first mixed in a mortar with a solid sorbent and then transferred to a polypropylene syringe containing a layer of clean-up co-sorbent. Analytes were eluted with a suitable solvent and further determined by gas chromatography with tandem mass spectrometry (GC-MS/MS). Under final conditions, diatomaceous earth and silica, deactivated to 10%, were used as inert dispersant and clean-up co-sorbent, respectively. Analytes were recovered using just 5 mL of dichloromethane, and this extract was concentrated and exchanged to 1 mL of isooctane. Further removal of co-extracted sulphur was achieved adding activated copper powder to final extracts, which were stored overnight, before injection in the GC-MS/MS system. The accuracy of the method was assessed with river and marine sediment samples showing different carbon contents and spiked at different concentrations in the range from 40 to 500 ng g −1 . Recoveries varied between 78% and 110% with associated standard deviations below 14%. The limits of quantification of the method stayed between 3 and 15 ng g −1 . Levels of target compounds in sediment samples ranged from not detected up to a maximum of 56 ng g −1 for Tinuvin 328.
    Keywords: Benzotriazole UV absorbers ; Sediment ; Matrix solid-phase dispersion ; Gas chromatography–mass spectrometry
    ISSN: 1618-2642
    E-ISSN: 1618-2650
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Language: English
    In: Water Research, 01 September 2017, Vol.120, pp.280-289
    Description: In this work, the reaction of four benzodiazepines (diazepam, oxazepam, nordazepam and temazepam) during water chlorination was studied by means of liquid chromatography-quadrupole-time of flight-mass spectrometry (LC-QTOF-MS). For those compounds that showed a significant degradation, i.e. diazepam, oxazepam and nordazepam, parameters affecting to the reaction kinetics (pH, chlorine and bromide level) were studied in detail and transformation products were tentatively identified. The oxidation reactions followed pseudofirst-order kinetics with rate constants in the range of 1.8–42.5 M  s , 0.13–1.16 M  s and 0.04–20.4 M  s corresponding to half-life values in the range of 1.9–146 min, 1.8–87 h and 2.5–637 h for oxazepam, nordazepam and diazepam, respectively, depending of the levels of studied parameters. Chlorine and pH affected significantly the reaction kinetics, where an increase of the pH resulted into a decrease of the reaction rate, whereas higher chlorine dosages led to faster kinetics, as expected in this case. The transformation of the studied benzodiazepines occurs mainly at the 1,4-diazepine 7-membered-ring, resulting in ring opening to form benzophenone derivatives or the formation of a 6-membered pyrimidine ring, leading to quinazoline derivatives. The formation of these by-products was also tested in real surface water samples observing kinetics of oxazepam degradation slower in river than in creek water, while the degradation of the two other benzodiazepines occurred only in the simpler sample (creek water). Finally, the acute and chronical toxicity and mutagenicity of precursors and transformation products were estimated using quantitative structure-activity relationship (QSAR) software tools: Ecological Structure Activity Relationships (ECOSAR) and Toxicity Estimation Software Tool (TEST), finding that some transformation products could be more toxic/mutagenic than the precursor drug, but additional test would be needed to confirm this fact.
    Keywords: Psychoactive Drugs ; High Resolution Mass Spectrometry ; Water Treatment ; Disinfection By-Products ; Engineering
    ISSN: 0043-1354
    E-ISSN: 1879-2448
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    Language: English
    In: Journal of Chromatography A, 2010, Vol.1217(46), pp.7208-7214
    Description: An inexpensive and effective sample preparation procedure for the determination of three ethylphenolic off-flavours (4-ethylphenol, 4-ethylguaiacol and 4-ethylcathecol) in wine samples is presented. Analytes were in situ acetylated and concentrated using a disposable silicone sorbent (DSS) exposed to the diluted sample. After that, the analytes were recovered with ethyl acetate and determined by gas chromatography with mass spectrometry. The influence of different parameters (volume of acetic anhydride, basic catalyst, ionic strength, sorbent format, sampling mode and extraction time) on the efficiency of derivatization and extraction steps is discussed. Under optimized conditions, 2 mL of wine were diluted with 15 mL of an aqueous solution of potassium bicarbonate (5%, m/v) in a 22 mL vessel, containing 2 g of sodium chloride. The volume of acetic anhydride and the extraction time were set at 90 μL and 2 h, and the extraction was carried out at room temperature (20 ± 2 °C). Analytes were concentrated using a silicone disc (5 mm diameter × 0.5 mm thickness) and further desorbed with 0.2 mL of ethyl acetate. The achieved limits of quantification (LOQs), defined as the concentration of each compound providing a signal 10 times higher than the baseline noise, stayed between 5 and 15 ng mL . The method provided a linear response range of up to 5000 ng mL and relative recoveries from 91% to 116%. The 4-ethylphenol off-flavour was detected in most red wine samples at concentrations of up to 2700 ng mL .
    Keywords: Ethylphenolic Off-Flavours ; Wine ; Acetylation ; Sorptive Extraction ; Gas Chromatography ; Mass Spectrometry ; Chemistry
    ISSN: 0021-9673
    E-ISSN: 18733778
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    Language: English
    In: Journal of Chromatography A
    Description: A novel procedure for the determination of nine selected fungicides (metalaxyl-M, azoxystrobin, myclobutanil, flusilazole, penconazole, tebuconazole, propiconazole, diniconazole and difenoconazole) in wine samples is presented. Sample enrichment and purification is simultaneously performed using mixed-mode, anion exchange and reversed-phase, OASIS MAX solid-phase extraction (SPE) cartridges. Analytes were determined by liquid chromatography coupled to tandem mass spectrometry using atmospheric pressure electrospray ionization (LC–ESI-MS/MS). Parameters affecting the chromatographic determination and the extraction-purification processes were thoroughly investigated. Under optimized conditions, 10 mL of wine were firstly diluted 1:1 with ultrapure water and then passed through the mixed-mode SPE cartridge at a flow of ca. 5 mL min . After a washing step with 5 mL of an aqueous NH OH solution (5%, w:v), analytes were recovered with just 1 mL of methanol and injected in the LC–MS/MS system without any additional purification. The selective extraction process avoided significant changes in the ionization efficiency for red and white wine extracts in comparison with pure standards in methanol. Performance of the method was good in terms of precision (RSDs 〈 11%) and accuracy (absolute recoveries 〉 72%, determined against pure standards in methanol) reporting method LOQs in the range of 0.01–0.79 ng mL for target compounds, which are far below the EU maxima residue levels (MRLs) for fungicides in vinification grapes and wine. Several commercial wines from different geographic areas in Spain were analyzed. In most samples, metalaxyl-M and azoxystrobin were found at concentrations up to several ng mL .
    Keywords: Fungicides ; Wine Analysis ; Mixed-Mode Solid Phase Extraction ; Liquid Chromatography Coupled to Tandem Mass Spectrometry ; Pesticides ; Chemistry
    ISSN: 0021-9673
    E-ISSN: 18733778
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    Language: English
    In: Journal of Chromatography A, June 7, 2013, Vol.1293, p.126(7)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.chroma.2013.03.050 Byline: J. Casado, I. Rodriguez, I. Carpinteiro, M. Ramil, R. Cela Abstract: acents Determination of benzotriazole UV stabilizers in sludge. acents Assessment of GC-QTOF-MS performance as selective determination technique. acents Simplified, low cost and solvent consuming sample preparation method. acents Confirmation of benzotriazole UV stabilizers ubiquity in sludge samples and reference materials. Author Affiliation: Departamento de Quimica Analitica, Nutricion y Bromatologia, Instituto de Investigacion y Analisis Alimentario (IIAA), Universidad de Santiago de Compostela, Santiago de Compostela 15782, Spain Article History: Received 30 January 2013; Revised 14 March 2013; Accepted 15 March 2013
    Keywords: Mass Spectrometry ; Sludge ; Chromatography
    ISSN: 0021-9673
    Source: Cengage Learning, Inc.
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    Language: English
    In: Analytical and Bioanalytical Chemistry, May, 2010, Vol.397(1), p.829(11)
    Description: Byline: Inmaculada Carpinteiro (1), Brais Abuin (1), Isaac Rodriguez (1), Rafael Cela (1), Maria Ramil (1) Keywords: UV stabilizers; Benzotriazoles; Water samples; Solid-phase microextraction; Gas chromatography; Mass spectrometry Abstract: A sensitive procedure for the determination of five ultraviolet (UV) absorbers, belonging to the benzotriazole class, in environmental water samples is proposed. Analytes were first extracted and concentrated from the matrix and then selectively determined by gas chromatography in combination with tandem mass spectrometry detection. The high lipophilic character of some of the investigated species resulted in a strong trend to remain sorbed on solid surfaces, even after addition of considerable percentages of methanol (up to 30%) to water. Thus, minimizing sample handling during the enrichment step is mandatory in order to obtain acceptable accuracy and precision. Solid-phase microextraction (SPME), as sample preparation approach, fulfilled the above requirement and provided acceptable figures of merit for the determination of target species in environmental water samples, including raw wastewater. Optimization of SPME conditions showed that the combination of headspace extraction, with a sample temperature of 100 degC and addition of 15 mg of NaCl per milliliter of sample rendered the best compromise in terms of extraction efficiency for all species. Considering a sampling time of 30 min with a poly(dimethylsiloxane)--divinylbenzene-coated SPME fiber, limits of quantification below 2 ng l.sup.-1 and relative standard deviations between 5% and 12% were achieved. Three of the five species included in this research were determined in raw wastewater with a maximum concentration of 57 ng l.sup.-1 for the Tinuvin 326 UV absorber. Figure Proposed structures for product ions observed in the MS/MS spectra of Tinuvin 326 Author Affiliation: (1) Departamento de Quimica Analitica, Nutricion y Bromatologia, Instituto de Investigacion y Analisis Alimentarios, Universidad de Santiago de Compostela, 15782, Santiago de Compostela, Spain Article History: Registration Date: 13/02/2010 Received Date: 15/12/2009 Accepted Date: 12/02/2010 Online Date: 14/03/2010
    Keywords: Wastewater ; Siloxanes ; Mass Spectrometry ; Gas Chromatography
    ISSN: 1618-2642
    Source: Cengage Learning, Inc.
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    Language: English
    In: Journal of Chromatography A, March 16, 2012, Vol.1229, p.79(7)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.chroma.2012.01.044 Byline: I. Carpinteiro, B. Abuin, I. Rodriguez, M. Ramil, R. Cela Keywords: Ethylphenol off-flavours; Wine; Dispersive liquid-liquid microextraction; Mixed-mode solid phase extraction Abstract: a* Selective ethylphenols determination in red wines. a* Wide linear response range. a* Overall extraction yields not affected by wine sample characteristics. a* High enrichment factors with low organic solvents and sample consumption. Author Affiliation: Departamento de Quimica Analitica, Nutricion y Bromatologia, Instituto de Investigacion y Analisis Alimentario (IIAA), Universidad de Santiago de Compostela, Santiago de Compostela 15782, Spain Article History: Received 16 November 2011; Revised 13 January 2012; Accepted 16 January 2012 Article Note: (footnote) [star] Presented at the 13th Conference on Instrumental Analysis, Barcelona, Spain, 14-16 November 2011.
    Keywords: Wine -- Analysis
    ISSN: 0021-9673
    Source: Cengage Learning, Inc.
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    Language: English
    In: Analytical and Bioanalytical Chemistry, 2012, Vol.402(7), pp.2471-2478
    Description: An improved selectivity method for the simultaneous determination of four benzotriazoles (benzotriazole, 4-methylbenzotriazole, 5-methylbenzotriazole, and 5,6-dimethyl-1 H -benzotriazole) and six benzothiazoles (benzothiazole, 2-hydroxybenzothiazole, 2-benzothiazolamine, mercaptobenzothiazole, 2-methylbenzothiazole, and 2-methylthiobenzothiazole) in aqueous matrices has been developed. Under optimal conditions, analytes are concentrated using a MAX solid-phase extraction (SPE) cartridge, based on divinylbenzene- N -vinylpyrrolidone functionalized with quaternary amine groups, which allows reversed-phase interactions in combination with ionic exchange. Selected compounds are recovered with methanol–acetone 7:3 ( v / v ) whereas acidic interferences remained attached to the sorbent, and as determined by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS), LOQs for surface, urban and industrial wastewater are in the range of 0.002–0.29 ng/mL. Figures of merit of the method revealed good precision (RSD% 〈12%), linearity ( R 2  〉 0.99) and accuracy (% R  = 80–100%) for surface waters and effluents allowing direct external standard quantification. For more complex samples, such as urban and industrial raw wastewater, either the standard addition method or pseudo-external standard calibration using matrix matched standards are recommended. Analysis of different real samples, surface, urban wastewater and, for the first time, metal industry wastewater, reflected concentrations up to 310 ng/mL. The methylbenzotriazole isomers ratio was also determined.
    Keywords: Benzotriazoles ; Benzothiazoles ; Water analysis ; Mixed-mode solid-phase extraction ; Liquid chromatography coupled to tandem mass spectrometry ; Emerging contaminants
    ISSN: 1618-2642
    E-ISSN: 1618-2650
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 9
    In: Nature Medicine, 2011, Vol.17(3), p.341
    Description: Pseudomonas aeruginosa is a Gram-negative pathogen that causes severe infections in immunocompromised individuals and individuals with cystic fibrosis or chronic obstructive pulmonary disease (COPD). Here we show that kinase suppressor of Ras-1 (Ksr1)-deficient mice are highly susceptible to pulmonary P. aeruginosa infection accompanied by uncontrolled pulmonary cytokine release, sepsis and death, whereas wild-type mice clear the infection. Ksr1 recruits and assembles inducible nitric oxide (NO) synthase (iNOS) and heat shock protein-90 (Hsp90) to enhance iNOS activity and to release NO upon infection. Ksr1 deficiency prevents lung alveolar macrophages and neutrophils from activating iNOS, producing NO and killing bacteria. Restoring NO production restores the bactericidal capability of Ksr1-deficient lung alveolar macrophages and neutrophils and rescues Ksr1-deficient mice from P. aeruginosa infection. Our findings suggest that Ksr1 functions as a previously unknown scaffold that enhances iNOS activity and is therefore crucial for the pulmonary response to P. aeruginosa infections.
    Keywords: Genes -- Physiological Aspects ; Genes -- Research ; Pseudomonas Aeruginosa Infections -- Prevention ; Pseudomonas Aeruginosa Infections -- Genetic Aspects ; Pseudomonas Aeruginosa Infections -- Research ; Protein Kinases -- Physiological Aspects ; Protein Kinases -- Research;
    ISSN: 1078-8956
    E-ISSN: 1546170X
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 10
    Language: English
    In: Journal of Chromatography A, 16 March 2012, Vol.1229, pp.79-85
    Description: ► Selective ethylphenols determination in red wines. ► Wide linear response range. ► Overall extraction yields not affected by wine sample characteristics. ► High enrichment factors with low organic solvents and sample consumption. Selectivity of mixed-mode solid-phase extraction (SPE) was combined with the concentration power of dispersive liquid–liquid microextraction (DLLME) to obtain a sensitive, low solvent consumption method for gas chromatography-mass spectrometry determination of ethylphenol off-flavours (4-ethylphenol, EP; 4-ethylguaicol, EG and 4-ethylcathecol, EC) in complex red wine samples. Under optimized conditions, limits of quantification (LOQs) between 0.3 and 0.8 ng mL were obtained using just 5 mL of wine and 0.06 mL of 1,1,1-trichloroethane (TCE) as extractant in the DLLME step. Analytes were acetylated after SPE and previously to DLLME concentration to enhance the performance of their GC–MS determination. The overall extraction efficiency of the method was unaffected by the particular characteristics of each wine; thus, accurate results (relative recoveries from 89 to 109% for samples spiked at concentrations from 20 to 1000 ng mL ) were obtained using matrix-matched standards, without requiring the use of the time consuming standard addition quantification methodology. The applicability of the method was demonstrated with the analysis of different red wines. Analytes concentrations varied from 6 to 2265 ng mL (EP), 0.8 to 251 ng mL (EG) and non-detected to 158 ng mL (EC).
    Keywords: Ethylphenol Off-Flavours ; Wine ; Dispersive Liquid–Liquid Microextraction ; Mixed-Mode Solid Phase Extraction ; Chemistry
    ISSN: 0021-9673
    E-ISSN: 18733778
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. Further information can be found on the KOBV privacy pages