| 1. |
- Ghaffarzadegan, Tannaz, et al.
(author)
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Determination of bile acids by hollow fibre liquid-phase microextraction coupled with gas chromatography.
- 2014
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In: Journal of Chromatography. B. - : Elsevier BV. - 1873-376X .- 1570-0232. ; 944, s. 69-74
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Journal article (peer-reviewed)abstract
- A method based on hollow-fibre liquid phase microextraction combined with gas chromatography was developed for determination of specific bile acids in caecal materials of rats. Nine unconjugated bile acids, including the primary bile acids (cholic acid, chenodeoxycholic acid and α-muricholic acid) and the secondary bile acids (lithocholic acid, deoxycholic acid, ursodeoxycholic acid, hyodeoxycholic acid, β-muricholic acid and ω-muricholic acid) were quantified. Extraction conditions were evaluated, including: sample pH, type of organic solvent and amount of caecal material to be extracted. To compensate for sample matrix effects during extraction the method of standard addition was applied. The satisfactory linearity (r(2)>0.9840), high recovery (84.2-108.7%) and good intra-assay (6.3-10.6%) and inter-assay (6.9-11.1%) precision illustrated the good performance of the present method. The method is rapid, simple and capable of detecting and determining bile acids with limit of detection (LOD) ranged from 0.002 to 0.067μg/mL and limits of quantification (LOQ) varied from 0.006 to 0.224μg/mL. The results indicated that the concentration of some secondary bile acids, which usually are associated with health problems, were lower in rats fed with fermentable dietary fibre compared with a fibre free control diet, while the concentration of primary bile acids, usually connected with positive health effects, were higher in rats fed with diets containing dietary fibre. Of the dietary fibres, guar gum and to some extent the mixture of pectin+guar gum had the most positive effects. Thus, it was concluded that the composition of bile acids can be affected by the type of diet.
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| 2. |
- Ghaffarzadegan, Tannaz, et al.
(author)
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Determination of free and conjugated bile acids in serum of Apoe(−/−) mice fed different lingonberry fractions by UHPLC-MS
- 2019
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In: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 9
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Journal article (peer-reviewed)abstract
- Bile acids (BAs) are known to be involved in cholesterol metabolism but interactions between the diet, BA profiles, gut microbiota and lipid metabolism have not been extensively explored. In the present study, primary and secondary BAs including their glycine and taurine-conjugated forms were quantified in serum of Apoe−/− mice by protein precipitation followed by reversed phase ultra-high-performance liquid chromatography and QTOF mass spectrometry. The mice were fed different lingonberry fractions (whole, insoluble and soluble) in a high-fat setting or cellulose in a high and low-fat setting. Serum concentrations of BAs in mice fed cellulose were higher with the high-fat diet compared to the low-fat diet (20–70%). Among the lingonberry diets, the diet containing whole lingonberries had the highest concentration of chenodeoxycholic acid (CDCA), ursodeoxycholic acid (UDCA), tauro-ursodeoxycholic acid (T-UDCA), α and ω-muricholic acids (MCA) and tauro-α-MCA (T-α-MCA), and the lowest concentration of tauro-cholic acid (T-CA), deoxycholic acid (DCA) and tauro-deoxycholic acid (T-DCA). The glycine-conjugated BAs were very similar with all diets. CDCA, UDCA and α-MCA correlated positively with Bifidobacterium and Prevotella, and T-UDCA, T-α-MCA and ω-MCA with Bacteroides and Parabacteroides.
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| 3. |
- Ghaffarzadegan, Tannaz, et al.
(author)
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Postprandial Responses of Serum Bile Acids in Healthy Humans After Ingestion of Turmeric Before Medium /High‐Fat Breakfasts
- 2019
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In: Molecular Nutrition and Food Research. - : Wiley. - 1613-4133 .- 1613-4125.
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Journal article (peer-reviewed)abstract
- Scope: Bile acids (BAs) are known to regulate a number of metabolic activities in the body. However, very little is known about how BAs are affected by diet. This study aimed to investigate whether a single-dose of turmeric-based beverage (TUR) before ingestion of medium- (MF) or high-fat (HF) breakfasts would improve the BA profile in healthy subjects. Methods and results: Twelve healthy subjects were assigned to a randomized crossover single-blind study. The subjects received iso-caloric MF or HF breakfasts after a drink containing flavored water with or without an extract of turmeric with at least one-week wash-out period between the treatments. Postprandial BAs were measured using protein precipitation followed by ultra-high-performance liquid chromatography-mass spectrometry analysis (UHPLC-MS). The concentration of BAs was generally higher after HF than MF breakfasts. Ingestion of TUR before MF breakfast increased the serum concentrations of free and conjugated forms of cholic and ursodeoxycholic acids, as well as the concentrations of chenodeoxycholic acid and its taurine-conjugated form. However, the concentration of conjugated forms of deoxycholic acid decreased when TUR was taken before HF breakfast. Conclusion: TUR ingestion before MF and HF breakfasts improved BA profiles and may therefore have potential health-promoting effects on BA metabolism.
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| 4. |
- Abdelaziz, Omar Y., et al.
(author)
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Biological valorization of low molecular weight lignin
- 2016
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In: Biotechnology Advances. - : Elsevier BV. - 0734-9750. ; 34:8, s. 1318-1346
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Research review (peer-reviewed)abstract
- Lignin is a major component of lignocellulosic biomass and as such, it is processed in enormous amounts in the pulp and paper industry worldwide. In such industry it mainly serves the purpose of a fuel to provide process steam and electricity, and to a minor extent to provide low grade heat for external purposes. Also from other biorefinery concepts, including 2nd generation ethanol, increasing amounts of lignin will be generated. Other uses for lignin – apart from fuel production – are of increasing interest not least in these new biorefinery concepts. These new uses can broadly be divided into application of the polymer as such, native or modified, or the use of lignin as a feedstock for the production of chemicals. The present review focuses on the latter and in particular the advances in the biological routes for chemicals production from lignin. Such a biological route will likely involve an initial depolymerization, which is followed by biological conversion of the obtained smaller lignin fragments. The conversion can be either a short catalytic conversion into desired chemicals, or a longer metabolic conversion. In this review, we give a brief summary of sources of lignin, methods of depolymerization, biological pathways for conversion of the lignin monomers and the analytical tools necessary for characterizing and evaluating key lignin attributes.
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| 5. |
- Abrahamsson, Victor, et al.
(author)
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Impact of injection solvents on supercritical fluid chromatography.
- 2013
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In: Journal of Chromatography A. - : Elsevier BV. - 0021-9673. ; 1306, s. 80-88
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Journal article (peer-reviewed)abstract
- Even though there has been a rapid development in instrumentation and applications of supercritical fluid chromatography (SFC), relatively little is known about retention mechanisms compared to high-performance liquid chromatography (HPLC). Much effort has been made to characterize the influence of injection solvents on chromatographic efficiency in HPLC, however has been left rather uninvestigated in the domain of SFC. In this study properties of different injection solvents have been studied and correlated with properties of seven various analytes on three different columns, a C18, a 2-ethylpyridine and a bare-silica column. Aided by calculations of correlation coefficients and principal component analysis (PCA), the physical properties of injection solvents and the interactions between injection solvent, solute and stationary phase were investigated. The findings of this work shows that interactions capable of masking accessible silanol groups on a C18 column are of importance in order to maximize the plate number. While solvents with dipolar and hydrogen bond interaction properties are associated negatively with chromatographic efficiency using polar columns. Properties such as molar density, vapor pressure and boiling point were related to sharper peaks, mostly likely because of solubility issues of the injection solvent into the methanol-modified carbon dioxide. However, no additional solubility due to hydrogen interactions between the injection solvent and the carbon dioxide in SFC was observed. Surface tension and viscosity was not particularly associated with a decrease in plate numbers. By increasing the injection volume a stronger correlation between solubility related properties and plate numbers were obtained. Additional experiments showed that the resistance in solubility became an issue when performing partial-loop injection where additional washing solvent entered the system, thus providing broadened peaks.
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| 6. |
- Al Hamimi, Said, et al.
(author)
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Screening of stationary phase selectivities for global lipid profiling by ultrahigh performance supercritical fluid chromatography
- 2018
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In: Journal of Chromatography A. - : Elsevier BV. - 0021-9673. ; 1548, s. 76-82
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Journal article (peer-reviewed)abstract
- The performance of seven sub-2-μm particle packed columns (2-picolylamine, 2-PIC; charged surface hybrid fluoro-phenyl, CSH-FP; high strength silica C18 SB, HSS-C18; diethylamine, DEA; 1-aminoanthracene, 1-AA; high density diol and ethylene bridged hybrid; BEH) was examined for lipid separation in ultra-high performance supercritical fluid chromatography (UHPSFC) coupled to quadrupole time-of-flight mass spectrometry. Based on the results of the column screening a method for profiling of multiple lipid species from the major lipid classes was developed. Stationary phases containing β-hydroxy amines, i.e. 1-AA, DEA and 2-PIC, yielded strong retention and poor peak shapes of zwitterionic lipids with primary amine groups, such as phosphatidylserines, phosphatidylethanolamines and its lyso forms. The BEH and HSS-C18 columns showed strong retention of polar and nonpolar lipids, respectively. The Diol column retained the majority of major lipid classes and also produced symmetric peaks. In addition, this column also produced the highest resolution within and between major lipid classes. An injection solvent composed of methanol:chloroform (1:2, v:v) and the addition of 20 mM ammonium formate in the mobile phase improved chromatographic separation and mass spectrometry detection in comparison to ammonium acetate or absence of additive. Finally, chromatographic and mass spectrometric parameters were optimized for the Diol column using a design of experiments approach. The separation mechanism on the Diol column depended on the lipid functionality and the length and degree of unsaturation of the acyl groups. The developed method could resolve 18 lipid classes and multiple lipids within each class, from blood serum and brain tissue in 11 min.
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| 7. |
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| 8. |
- Azeem, Hafiz Abdul, et al.
(author)
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Extending the scope of dispersive liquid–liquid microextraction for trace analysis of 3-methyl-1,2,3-butanetricarboxylic acid in atmospheric aerosols leading to the discovery of iron(III) complexes
- 2019
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In: Analytical and Bioanalytical Chemistry. - : Springer Science and Business Media LLC. - 1618-2642 .- 1618-2650. ; 411:13, s. 2937-2944
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Journal article (peer-reviewed)abstract
- 3-Methyl-1,2,3-butanetricarboxylic acid (MBTCA) is a secondary organic aerosol and can be used as a unique emission marker of biogenic emissions of monoterpenes. Seasonal variations and differences in vegetation cover around the world may lead to low atmospheric MBTCA concentrations, in many cases too low to be measured. Hence, an important tool to quantify the contribution of terrestrial vegetation to the loading of secondary organic aerosol may be compromised. To meet this challenge, a dispersive liquid–liquid microextraction (DLLME) method, known for the extraction of hydrophobic compounds, was extended to the extraction of polar organic compounds like MBTCA without compromising the efficiency of the method. The extraction solvent was fine-tuned using tri-n-octyl phosphine oxide as additive. A multivariate experimental design was applied for deeper understanding of significant variables and interactions between them. The optimum extraction conditions included 1-octanol with 15% tri-n-octyl phosphine oxide (w/w) as extraction solvent, methanol as dispersive solvent, 25% NaCl dissolved in 5 mL sample (w/w) acidified to pH 2 using HNO 3 , and extraction time of 15 min. A limit of detection of 0.12 pg/m 3 in air was achieved. Furthermore, unique complexation behavior of MBTCA with iron(III) was found when analyzed with ultra-high-performance liquid chromatography coupled with electrospray ionization–quadrupole time-of-flight mass spectrometry (UHPLC–ESI–QToF). A comprehensive overview of this complexation behavior of MBTCA was examined with systematically designed experiments. This newly discovered behavior of MBTCA will be of interest for further research on organometallic photooxidation chemistry of atmospheric aerosols. [Figure not available: see fulltext.].
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| 9. |
- Azeem, Hafiz Abdul, et al.
(author)
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Towards the isolation and estimation of elemental carbon in atmospheric aerosols using supercritical fluid extraction and thermo-optical analysis
- 2017
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In: Analytical and Bioanalytical Chemistry. - : Springer Science and Business Media LLC. - 1618-2642 .- 1618-2650. ; 409:17, s. 4293-4300
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Journal article (peer-reviewed)abstract
- Air-starved combustion of biomass and fossil fuels releases aerosols, including airborne carbonaceous particles, causing negative climatic and health effects. Radiocarbon analysis of the elemental carbon (EC) fraction can help apportion sources of its emission, which is greatly constrained by the challenges in isolation of EC from organic compounds in atmospheric aerosols. The isolation of EC using thermo-optical analysis is however biased by the presence of interfering compounds that undergo pyrolysis during the analysis. EC is considered insoluble in all acidic, basic, and organic solvents. Based on the property of insolubility, a sample preparation method using supercritical CO2 and methanol as co-solvent was developed to remove interfering organic compounds. The efficiency of the method was studied by varying the density of supercritical carbon dioxide by means of temperature and pressure and by varying the methanol content. Supercritical CO2 with 10% methanol by volume at a temperature of 60 °C, a pressure of 350 bar and 20 min static mode extraction were found to be the most suitable conditions for the removal of 59 ± 3% organic carbon, including compounds responsible for pyrolysis with 78 ± 16% EC recovery. The results indicate that the method has potential for the estimation and isolation of EC from OC for subsequent analysis methods and source apportionment studies.
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| 10. |
- Cui, Jingwen, et al.
(author)
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Extraction with Water-in-Carbon Dioxide Microemulsions : A Case Study on Steviol Glycosides
- 2019
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In: Journal of Surfactants and Detergents. - : Wiley. - 1097-3958 .- 1558-9293. ; 22:6, s. 1505-1514
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Journal article (peer-reviewed)abstract
- This work explores the use of water-in-supercritical carbon dioxide (scCO2) microemulsions for the extraction of polar metabolites from plants. Stevia rebaudiana Bertoni leaves and polyethylene glycol trimethylnonyl ether (TMN) surfactants were selected for a case study. A CO2-water-TMN 10 mixture at 35 °C and 30.0 MPa extracted 7 mg target analyte/g dry leaves. The extraction was proven to occur due to a water-surfactant liquid solution rather than a water-in-CO2 microemulsion. Using a modified extraction setup, the microemulsion was created prior to extraction. TMN 6 was able to dissolve enough water in CO2 to extract steviol glycosides, in detectable but very small amounts.
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