| 1. |
- Gordi, Toufigh, et al.
(författare)
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Direct analysis of artemisinin in plasma and saliva using coupled-column high-performance liquid chromatography with a restricted-access material pre-column
- 2000
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Ingår i: Journal of Chromatography B. - 1387-2273 .- 1878-5603. ; 742:1, s. 155-162
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Tidskriftsartikel (refereegranskat)abstract
- A previously established HPLC system with post-column derivatization for the analysis of artemisinin was coupled to an ADS (alkyl-diol silica) pre-column, allowing direct and repetitive injection of protein-rich fluids such as plasma. The limit of quantitation for 100 μl of plasma was 10 ng/ml (CV=10.5%) while concentrations down to 2 ng/ml could be quantified for 1.00 ml saliva samples (CV=11.1%). The system was linear in the tested range of 10–2000 ng/ml for plasma and 2–240 ng/ml for saliva samples, respectively. This paper introduces coupled column HPLC as a simplified method for the routine analysis of artemisinin in biological fluids.
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| 2. |
- Idborg, Helena, et al.
(författare)
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Metabolic fingerprinting of rat urine by LC/MS. : Part1. Analysis by hydrophilic interaction liquid chromatography-electrospray ionization mass spectrometry
- 2005
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Ingår i: Journal of Chromatography B. - : Elsevier BV. - 1387-2273 .- 1878-5603 .- 1570-0232 .- 1873-376X. ; 828:1-2, s. 9-13
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Tidskriftsartikel (refereegranskat)abstract
- Complex biological samples, such as urine, contain a very large number of endogenous metabolites reflecting the metabolic state of an organism. Metabolite patterns can provide a comprehensive signature of the physiological state of an organism as well as insights into specific biochemical processes. Although the metabolites excreted in urine are commonly highly polar, the samples are generally analyzed using reversed-phase liquid chromatography mass spectrometry (RP-LC/MS). In Part I of this work, a method for detecting highly polar metabolites by hydrophilic interaction liquid chromatography-electrospray ionization mass spectrometry (HILIC/ESI-MS) is described as a complement to RP-LC/ESI-MS. In addition, in an accompanying paper (Part 2), different multivariate approaches to extracting information from the resulting complex data are described to enable metabolic fingerprints to be obtained. The coverage of the method for the screening of as many metabolites as possible is highly improved by analyzing the urine samples using both a C-18 column and a ZIC (R)-HILIC column. The latter was found to be a good alternative when analyzing highly polar compounds, e.g., hydroxyproline and creatinine, to columns typically used for reversed-phase liquid chromatography. (c) 2005 Elsevier B.V. All rights reserved.
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| 3. |
- Idborg, Helena, et al.
(författare)
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Metabolic fingerprinting of rat urine by LC/MS. : Part 2. Data pretreatment methods for handling of complex data
- 2005
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Ingår i: Journal of Chromatography B. - : Elsevier BV. - 1387-2273 .- 1878-5603 .- 1570-0232. ; 828:1-2, s. 14-20
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Tidskriftsartikel (refereegranskat)abstract
- Metabolic fingerprinting of biofluids like urine is a useful technique for detecting differences between individuals. With this approach, it might be possible to classify samples according to their biological relevance. In Part I of this work a method for the comprehensive screening of metabolites was described [H. Idborg, L. Zamani, P-O. Edlund, I. Schuppe-Koistinen, S.P. Jacobsson, Part 1, J. Chromatogr. B 828 (2005) 9], using two different liquid chromatography (LC) column set-ups and detection by electrospray ionization mass spectrometry (ESI-MS). Data pretreatment of the resulting data described in [H. Idborg, L. Zamani, P-O. Edlund, 1. Schuppe-Koistinen, S.P. Jacobsson, Part 1, J. Chromatogr. B 828 (2005) 9] is needed to reduce the complexity of the data and to obtain useful metabolic fingerprints. Three different approaches, i.e., reduced dimensionality (RD), MarkerLynx (TM), and MS Resolver (TM), were compared for the extraction of information. The pretreated data were then subjected to multivariate data analysis by partial least squares discriminant analysis (PLS-DA) for classification. By combining two different chromatographic procedures and data analysis, the detection of metabolites was enhanced as well as the finding of metabolic fingerprints that govern classification. Additional potential biomarkers or xenobiotic metabolites were detected in the fraction containing highly polar compounds that are normally discarded when using reversed-phase liquid chromatography.
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| 4. |
- Lindner, Karl-Johan, et al.
(författare)
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Analysis of l-[methyl-11C]methionine and metabolites in human plasma by an automated solid-phase extraction and a high-performance liquid chromatographic procedure
- 1996
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Ingår i: Journal of Chromatography B. - : Elsevier BV. - 1387-2273 .- 1878-5603. ; 679:1-2, s. 13-19
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Tidskriftsartikel (refereegranskat)abstract
- A fully automated method for separation of l-[methyl-11C]Methionine from metabolites in patient plasma was developed. l-[methyl-11C]Methionine was isolated from plasma by solid-phase extraction (SPE). The radioactivity retained on the SPE column was eluted and injected onto the HPLC system for separation of in vivo formed l-[methyl-11C]methionine radiolabeled metabolites. The yield through the isolation procedure and HPLC analysis was greater than 95% with a precision better than 5% (R.S.D.). The calculated rate of l-[methyl-11C]methionine transport into tumor tissue was markedly different with and without compensation for radiolabeled metabolises in patient plasma.
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| 5. |
- Lundahl, Per, et al.
(författare)
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Chromatographic approaches to liposomes, proteoliposomes and biomembrane vesicles
- 1999
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Ingår i: Journal of Chromatography B. - 1387-2273 .- 1878-5603. ; 722:1-2, s. 103-120
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Tidskriftsartikel (refereegranskat)abstract
- Size-exclusion chromatography has been used for fractionation of liposomes, proteoliposomes and biomembrane vesicles of up to approximately 500 nm in size and for separation of these entities from smaller components. Liposome sizes, encapsulation stability, and solute affinities for membrane proteins have been determined. Counter-current distribution in aqueous two-phase systems has widened the range of applications to larger structures. Immobilized biomembrane vesicles and (proteo)liposomes provide stationary phases for chromatographic analysis of specific or nonspecific membrane-solute interactions.
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| 6. |
- Malm, Mikaela, et al.
(författare)
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Determination of eflornithine enantiomers in plasma, by solid-phase extraction and liquid chromatography with evaporative light-scattering detection
- 2007
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Ingår i: Journal of chromatography. B. - : Elsevier BV. - 1570-0232 .- 1873-376X .- 1387-2273 .- 1878-5603. ; 846:1-2, s. 98-104
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Tidskriftsartikel (refereegranskat)abstract
- A bioanalytical method for determination of eflornithine (DFMO) in 1000 μL human plasma has been developed and validated. DFMO and the internal standard (IS) were analysed by liquid chromatography with evaporative light-scattering detection (ELSD). Separation was performed on a Chirobiotic TAG (250 mm × 4.6 mm) column with ethanol (99.5%):0.01 mol/L acetic acid-triethylamine buffer at the rate of 25:75% (v/v) with flow rate of 1.0 mL/min. For d-DFMO in plasma the inter-assay precision was 6.5% at 75 μmol/L, 6.6% at 375 μmol/L and 5.8% at 750 μmol/L. For l-DFMO in plasma the inter-assay precision was 10.4% at 75 μmol/L, 6.5% at 375 μmol/L and 5.0% at 750 μmol/L. The lower limit of quantification (LLOQ) was determined to 25 μmol/L where the precision was 4.3% and 5.7%, respectively.
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| 7. |
- Persson, Karin, et al.
(författare)
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Fractional Factorial Design Optimization of the Separation of Pilocarpine and its Degradation Products by Capillary Electrophoresis
- 1997
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Ingår i: Journal of Chromatography B. - 1387-2273 .- 1878-5603. ; 697:1-2, s. 207-215
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Tidskriftsartikel (refereegranskat)abstract
- The separation of pilocarpine and its degradation products by micellar electrokinetic capillary chromatography (MECC) has been optimized by using fractional factorial design of the experiments. Critical parameters were identified in a screening design, and an optimization design was used to optimize the separation. The optimal separation method was based on a borate buffer with sodium dodecyl sulfate (SDS). It is concluded that by using fractional factorial design it is possible to improve the separation of pilocarpine, its trans epimer, isopilocarpine and their hydrolysis products, pilocarpic acid and isopilocarpic acid.
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| 8. |
- Öhman, Daniel, 1973-, et al.
(författare)
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On-line extraction using an alkyl-diol silica precolumn for racemic citalopram and its metabolites in plasma : results compared with solid-phase extraction methodology
- 2001
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Ingår i: Journal of Chromatography B. - 1387-2273 .- 1878-5603. ; 753:2, s. 365-373
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Tidskriftsartikel (refereegranskat)abstract
- Sample preparation is usually the most critical and time consuming step when using HPLC for drug analysis in biological matrixes. Sample extracts have to be clean considering both chromatographic interferences and column maintenance. To meet some of these criteria a fully automated on-line extraction (OLE) analysis method was developed for the antidepressant drug citalopram and its two demethylated metabolites, using an RP-C4-ADS extraction column. A comparison between the new OLE method and an off-line solid-phase extraction method showed that the two methodologies were equal in analytical precision but that the OLE method was faster and therefore superior in sample capacity per day.
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| 9. |
- Gesar, Berit, 1959-, et al.
(författare)
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Hip fracture; an interruption that has consequences four months later : A qualitative study
- 2017
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Ingår i: International Journal of Orthopaedic and Trauma Nursing. - : Elsevier. - 1878-1241 .- 1878-1292. ; 26, s. 43-48
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Effects following a hip fracture often lead to functional disabilities and increased dependence on others. Although persons sustaining a hip fracture constitute a heterogeneous group in Swedish health care, they tend to be treated as a homogenous one.AIM: The aim of this study was to reveal how previously healthy people, aged 65 years and older, described how they had adapted to daily life four months after a hip fracture.METHOD: The follow-up interviews were performed by the first author four months after the hip fracture. Data were analysed using conventional inductive content analysis.FINDINGS: The results from the interviews highlight that sustaining a hip fracture - even four months later - was seen by the participants as an interruption leading to lasting consequences for everyday life. The recovery process during this period was complex and consisted of both physical and psychological strain. Some were resigned, some strived in order to regain independence and some handled the situation by means of self-confidence and self-efficacy.CONCLUSION: Previous healthy and independently-living participants described, in different ways that the hip fracture was an interruption that still affected everyday life. The absence of psychological support may be one of the reasons for dependency after four months.
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| 10. |
- Bal, Karol, et al.
(författare)
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New and simple procedure for the determination of muramic acid in chemically complex environments by gas chromatography-ion trap tandem mass spectrometry
- 2000
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Ingår i: Journal of Chromatography. B. - 1387-2273. ; 738:1, s. 57-65
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Tidskriftsartikel (refereegranskat)abstract
- A gas chromatographic-ion trap tandem mass spectrometric method was developed for the quantification of muramic acid, a marker of bacterial peptidoglycan, in environmental and clinical specimens. Samples (bacteria, house dust and urine) were heated in methanolic hydrochloric acid overnight and extracted with hexane for removal of hydrophobic compounds. The aqueous phase was evaporated and heated in acetic anhydride and pyridine after which the product, the acetate derivative, was washed with dilute hydrochloric acid and water. The described method is both rapid and simple to apply, and produces a stable derivative. It should become widely used for measuring peptidoglycan in chemically complex environments.
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