| 1. |
- Petersson, Patrik, et al.
(författare)
-
Why ultra high performance liquid chromatography produces more tailing peaks than high performance liquid chromatography, why it does not matter and how it can be addressed
- 2011
-
Ingår i: Journal of chromatography. B. - : Elsevier BV. - 1570-0232 .- 1873-376X .- 0021-9673 .- 1873-3778. ; 1218:39, s. 6914-6921
-
Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study is to demonstrate, with experiments and with computer simulations based on a firm chromatographic theory, that the wide spread perception of that the United States Pharmacopeia tailing factor must be lower than 2 (Tf < 2) is questionable when using the latest generation of LC equipment. It is shown that highly efficient LC separations like those obtained with sub-2 μm porous and 2.7 μm superficially porous particles (UHPLC) produce significantly higher Tf-values than the corresponding separation based on 3 μm porous particles (HPLC) when the same amount of sample is injected. Still UHPLC separations provide a better resolution to adjacent peaks. Expressions have been derived that describe how the Tf-value changes with particle size or number of theoretical plates. Expressions have also been derived that can be used to scale the injection volume based on particle size or number of theoretical plates to maintain the Tf-value when translating a HPLC separation to the corresponding UHPLC separation. An aspect that has been ignored in previous publications. Finally, data obtained from columns with different age/condition indicate that Tf-values should be complemented by a peak width measure to provide a more objective quality measure.
|
|
| 2. |
- Abdel–Khalik, Jonas, et al.
(författare)
-
Development of a solid phase extraction method for the simultaneous determination of steroid hormones in H295R cell line using liquid chromatography–tandem mass spectrometry
- 2013
-
Ingår i: Journal of chromatography. B. - 1570-0232 .- 1873-376X. ; 935:September, s. 61-69
-
Tidskriftsartikel (refereegranskat)abstract
- The H295R in vitro cell line produces the majority of the steroidogenesis, for which reason it is commonly used as a screening tool for endocrine disrupting chemicals. Simultaneous determination of the precursor cholesterol and key steroid hormones could give a broad insight into the mechanistic disruption of the steroidogenesis. Steroid hormones have primarily been extracted from H295R incubation medium by means of liquid-liquid extraction (LLE) and the obtained recoveries and matrix effects have typically not been stated or assessed. In the present study a solid-phase extraction (SPE) method was developed and validated for the simultaneous extraction of cholesterol and five key steroid hormones pregnenolone, 17-hydroxyprogesterone, testosterone, cortisol and aldosterone from H295R incubation medium, and finally detected by LC-MS/MS. Cholesterol was recovered at a level of 55.7%, while steroid hormone recoveries ranged from 98.2 to 109.4%. Matrix effects varied between -0.6% and 62.8%. Intra-day precision was deemed acceptable, but the inter-day precision for pregnenolone and aldosterone exceeded the precision limit of 15% RSD. Although LLE has been the most frequently used extraction method in H295R studies, however, our investigation has shown that SPE may relatively easily extract and recover steroid hormones, potentially replacing LLE.
|
|
| 3. |
- Abdel–Khalik, Jonas, et al.
(författare)
-
Simultaneous determination of endogenous steroid hormones in human and animal plasma and serum by liquid or gas chromatography coupled to tandem mass spectrometry
- 2013
-
Ingår i: Journal of chromatography. B. - 1570-0232 .- 1873-376X. ; 928:June, s. 59-77
-
Tidskriftsartikel (refereegranskat)abstract
- Analytical methodologies based on liquid or gas chromatography coupled to tandem mass spectrometry for the simultaneous determination of two or more endogenous steroid hormones in human and animal plasma and serum has received increased attention the last few years. Especially in the clinical setting steroid profiling is of major importance in disease diagnostics. This paper discusses recent findings in such multi-steroid hormone procedures published from 2001 to 2012. The aim was to elucidate possible relationships between chosen analytical technique and the obtained analyte sensitivity for endogenous steroid hormones. By evaluating the success, at which the currently applied techniques have been utilized, more general knowledge on the field is provided. Furthermore the evaluation provides directions in which future studies may be interesting to conduct.
|
|
| 4. |
|
|
| 5. |
- Amelina, Hanna, et al.
(författare)
-
Quantitative subproteomic analysis of age-related changes in mouse liver peroxisomes by iTRAQ LC-MS/MS
- 2011
-
Ingår i: Journal of chromatography. B. - : Elsevier BV. - 1570-0232 .- 1873-376X. ; 879:30, s. 3393-3400
-
Tidskriftsartikel (refereegranskat)abstract
- Aging is a complex multifactorial phenomenon, which is believed to result from the accumulation of cellular damage to biological macromolecules. Peroxisomes recently emerged as another important source of reactive oxygen species (ROS) production in addition to mitochondria. However, the role of these organelles in the process of aging is still not clear. The aim of this study was to characterize the changes in protein expression profiles of young (10 weeks old) versus old (18 months old) mouse liver peroxisome-enriched fractions. We have applied shotgun proteomic approach based on liquid chromatography and tandem mass spectrometry (LC-MS/MS) combined with iTRAQ (isobaric tags for relative and absolute quantitation) labeling that allows comparative quantitative multiplex analysis. Our analysis led to identification and quantification of 150 proteins, 8 out of which were differentially expressed between two age groups at a statistically significant level (p < 0.05), with folds ranging from 1.2 to 4.1. These proteins involved in peroxisornal beta-oxidation, detoxification of xenobiotics and production of ROS. Noteworthy, differences in liver proteome have been observed between as well as within different age groups. In conclusion, our subproteomic quantitative study suggests that mouse liver proteome is sufficiently maintained until certain age.
|
|
| 6. |
- Bankefors, Johan, et al.
(författare)
-
Multidimensional profiling of components in complex mixtures of natural products for metabolic analysis, proof of concept: Application to Quillaja saponins
- 2010
-
Ingår i: Journal of Chromatography B. - : Elsevier BV. - 1570-0232 .- 1873-376X. ; 878, s. 471-476
-
Tidskriftsartikel (refereegranskat)abstract
- A method for separation and detection of major and minor components in complex Mixtures has been developed, utilising two-dimensional high-performance liquid chromatography (2D-HPLC) combined with electrospray ionisation ion-trap multiple-stage mass spectrometry (ESI-ITMS(n)). Chromatographic conditions were matched with mass spectrometric detection to maximise the number of components that could be separated. The described procedure has proven useful to discern several hundreds of saponin components when applied to Quillaja saponaria Molina bark extracts. The discrimination of each saponin component relies oil the fact that three coordinates (x,y,z) for each component can be derived from the retention time of the two chromatographic steps (x,y) and the M/Z-values from the multiple-stage mass spectrometry (z(n), n = 1, 2....). Thus an improved graphical representation was obtained by combining retention times from the two-stage separation with +MS(1) (z(1)) and the additional structural information from the second mass stage +MS(2) (z(2), z(3)) corresponding to the main fragment ions. By this approach three-dimensional plots can be made that reveal both the chromatographic and structural properties of a specific mixture which can be useful in fingerprinting of complex mixtures. (C) 2009 Elsevier B.V. All rights reserved.
|
|
| 7. |
- Baranowska, Irena, et al.
(författare)
-
Clinical applications of fast liquid chromatography: A review on the analysis of cardiovascular drugs and their metabolites
- 2013
-
Ingår i: Journal of chromatography. B. - : Elsevier. - 1570-0232 .- 1873-376X. ; 927:SI, s. 54-79
-
Forskningsöversikt (refereegranskat)abstract
- One of the major challenges facing the medicine today is developing new therapies that enhance human health. To help address these challenges the utilization of analytical technologies and high-throughput automated platforms has been employed; in order to perform more experiments in a shorter time frame with increased data quality. In the last decade various analytical strategies have been established to enhance separation speed and efficiency in liquid chromatography applications. Liquid chromatography is an increasingly important tool for monitoring drugs and their metabolites. Furthermore, liquid chromatography has played an important role in pharmacokinetics and metabolism studies at these drug development stages since its introduction. This paper provides an overview of current trends in fast chromatography for the analysis of cardiovascular drugs and their metabolites in clinical applications. Current trends in fast liquid chromatographic separations involve monolith technologies, fused-core columns, high-temperature liquid chromatography (HTLC) and ultra-high performance liquid chromatography (UHPLC). The high specificity in combination with high sensitivity makes it an attractive complementary method to traditional methodology used for routine applications. The practical aspects of, recent developments in and the present status of fast chromatography for the analysis of biological fluids for therapeutic drug and metabolite monitoring, pharmacokinetic studies and bioequivalence studies are presented.
|
|
| 8. |
|
|
| 9. |
- Bergström, Maria, et al.
(författare)
-
Elucidating the selectivity of recombinant forms of Aleuria aurantia lectin using weak affinity chromatography
- 2012
-
Ingår i: Journal of chromatography. B. - : Elsevier. - 1570-0232 .- 1873-376X. ; 885, s. 66-72
-
Tidskriftsartikel (refereegranskat)abstract
- Aberrant glycosylation is connected to several pathological conditions and lectins are useful tools to characterize glycosylated biomarkers. The Aleuria aurantia lectin (AAL) is of special interest since it interacts with all types of fucosylated saccharides. AAL has been expressed in Escherichia coil as a fully functional recombinant protein. Engineered variants of AAL have been developed with the aim of creating monovalent lectins with more homogenous binding characteristics. Four different forms of AAL were studied in the present work: native AAL purified from A. aurantia mushrooms, recombinant AAL dimer, recombinant AAL monomer and recombinant AAL site 2 (S2-AAL). The affinities of these AAL forms toward a number of saccharides were determined with weak affinity chromatography (WAC). Disaccharides with fucose linked alpha 1-3 to GIcNAc interacted with higher affinity compared to fucose linked alpha 1-6 or alpha 1-4 and the obtained dissociation constants (K-d) were in the range of 10 mu M for all AAL forms. Tetra- and pentasaccharides with fucose in alpha 1-2, alpha 1-3 or alpha 1-4 had K-d values ranging from 0.1 to 7 mM while a large alpha 1-6 fucosylated oligosaccharide had a K-d of about 20 mu M. The recombinant multivalent AAL forms and native AAL exhibited similar affinities toward all saccharides, but S2-AAL had a lower affinity especially regarding a sialic acid containing fucosylated saccharide. It was demonstrated that WAC is a valuable technique in determining the detailed binding profile of the lectins. Specific advantages with WAC include a low consumption of non-labeled saccharides, possibility to analyze mixtures and a simple procedure using standard HPLC equipment.
|
|
| 10. |
- Casas, Monica Escolà, et al.
(författare)
-
Analytical sample preparation strategies for the determination of antimalarial drugs in human whole blood, plasma and urine
- 2014
-
Ingår i: Journal of chromatography. B. - 1570-0232 .- 1873-376X. ; 962, s. 109-131
-
Tidskriftsartikel (refereegranskat)abstract
- Antimalarial drugs commonly referred to as antimalarials, include a variety of compounds with different physicochemical properties. There is a lack of information on antimalarial distribution in the body over time after administration, e.g. the drug concentrations in whole blood, plasma, and urine, which must be improved in order to advance curing the parasitic disease malaria. A key problem also lies in that pharmacokinetic studies not always are performed in patient groups that may benefit most of the treatment such as children, pregnancy and lower-weight ethnic populations. Here we review the available sample preparation strategies combined with liquid chromatographic (LC) analysis to determine antimalarials in whole blood, plasma and urine published over the last decade. Sample preparation can be done by protein precipitation, solid-phase extraction, liquid-liquid extraction or dilution. After LC separation, the preferred detection tool is tandem mass spectrometry (MS/MS) but other detection methods have been used e.g. UV, fluorescence and electrochemical detection. Major trends for sample preparation of the different groups of antimalarials for each matrix and its detection have been summarized. Finally, the main problems that the researchers have dealt with are highlighted. This information will aid analytical chemists in the development of novel methods for determining existing antimalarials and upcoming new drugs
|
|
