| 1. |
- Gottschalk, Ingo, et al.
(författare)
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Improved lectin-mediated immobilization of human red blood cells in superporous agarose beads
- 2003
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Ingår i: Journal of chromatography. B. - 1570-0232 .- 1873-376X. ; 784:1, s. 203-208
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Tidskriftsartikel (refereegranskat)abstract
- A new type of agarose bead, superporous agarose, was used as a gel support for immobilization of human red blood cells (RBCs) mediated by wheat germ lectin. The number of immobilized cells was similar to that obtained with commercial wheat germ lectin–agarose but the cell stability appeared to be superior. This allowed improved frontal affinity chromatographic analyses of cytochalasin B (CB)-binding to the glucose transporter GLUT1 which established a ratio of one CB-binding site per GLUT1 dimer for both plain RBCs or those treated with different poly amino acids. The measured dissociation constants, 70±14 nM for CB and 12±3 mM for glucose binding to GLUT1, are similar to those reported earlier.
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| 2. |
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| 3. |
- Amini, Nahid, et al.
(författare)
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Feasibility of an on-line restricted access material/liquidchromatography/tandem mass spectrometry method in the rapid and sensitive determination of organophosphorustriesters in human blood plasma
- 2003
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Ingår i: Journal of chromatography. B. - 1570-0232 .- 1873-376X. ; 795:2, s. 245-256
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Tidskriftsartikel (refereegranskat)abstract
- A rapid on-line solid phase extraction/liquid chromatography/tandem mass spectrometry (SPE/LC/MS/MS) method usingrestricted access material (RAM) was developed for the simultaneous determination of eight organophosphorus triesters inuntreated human blood plasma. In a process involving column-switching techniques, the analytes were enriched on the RAMcolumn, separated using a C-18 analytical column and detected with LC/MS. Tandem mass spectrometrywas used to characterizeand quantify the analytes. To elucidate the fragmentation pathway of a number of the analytes, MS3 experiments using an iontrap mass spectrometer were performed. The matrix effects associated with using APCI and ESI interfaces were investigated.The recoveries obtained were in the range 60–92% (R.S.D. < 6%), with estimated detection limits between 0.2 and 1.8 ng/mlof plasma, and the total analysis time was 27 min.
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| 4. |
- Bergström, Sara K., et al.
(författare)
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On-line coupling of microdialysis to packed capillary column liquid chromatography-tandem mass spectrometry demonstrated by measurement of free concentrations of ropivacaine and metabolite from spiked plasma samples
- 2002
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Ingår i: Journal of chromatography. B. - 1570-0232 .- 1873-376X. ; 775:1, s. 79-87
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Tidskriftsartikel (refereegranskat)abstract
- An on-line coupling of microdialysis to a packed capillary column switching liquid chromatographic system (0.2 mm I.D.) and mass spectrometric detection was developed. The microdialysates were collected in the loop of the first of three valves, coupled in direct series. A deuterated internal standard was added on-line by the middle valve and the third valve operated both a pre-column, for desalting of the physiological buffer used in the sampling procedure, and a separation column. The on-line system was used to study free concentrations of ropivacaine and its metabolite (PPX) in human plasma samples. The analytes were detected by electrospray ionization in a tandem mass spectrometer operating in multiple reaction monitoring mode. The free fractions of ropivacaine (200 nM total concentration) and PPX (20 nM total concentration) in spiked plasma samples were 12±3 and 47±5% (±standard deviation for day-to-day variations, n=3), respectively.
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| 5. |
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| 6. |
- Eriksson, Kåre, et al.
(författare)
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Quantification of melatonin in human saliva by liquid chromatography-tandem mass spectrometry using stable isotope dilution
- 2003
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Ingår i: Journal of chromatography. B. - : Elsevier. - 1570-0232 .- 1873-376X. ; 794:1, s. 115-123
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Tidskriftsartikel (refereegranskat)abstract
- A method for the determination of melatonin in human saliva has been developed using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS-MS). Saliva was collected in plastic tubes. 7-D-Melatonin was added as internal standard and the samples were cleaned and concentrated by solid-phase extraction. The limit of detection was 1.05 pg x ml(-1) and the limit of quantification was 3.0 pg x ml(-1). The accuracy of the method was +/-14% at 5.60 pg x ml(-1) and +/-9% at 19.6 pg x ml(-1). The precision was +/-13% at 6.18 pg x ml(-1) and +/-11% at 31.2 pg x ml(-1), respectively. Our HPLC-MS-MS method shows a high sensitivity and specificity for melatonin and more reliable results compared with a radioimmunoassay. The chromatographic method has been used to determine the circadian rhythm of melatonin among three nurses working the night shift and a patient suffering from an inability to fall asleep at night.
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| 7. |
- Foyn Bruun, Cathrine, 1959-
(författare)
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Enrichment of serum amyloid proteins by hydrophobic interaction chromatography combined with two-dimensional electrophoresis with immobilised pH gradients
- 2003
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Ingår i: Journal of chromatography. B. - 1570-0232 .- 1873-376X. ; 790:1-2, s. 355-363
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Tidskriftsartikel (refereegranskat)abstract
- Serum amyloid A protein was subjected to one-step octyl-Sepharose extraction in three different dimensions. Elution was performed partly without UV recording, and with urea or guanidine-based buffers. The eluent was applied directly to denaturing two-dimensional electrophoresis with immobilised pH gradient, or octyl-Sepharose extracted fractions were pooled and lyophilised before application. Proteins were characterised by N-terminal analysis or mass spectrometry. In most of the species that were studied, previously undescribed serum amyloid proteins were detected. Compared to conventional strategies, the presented techniques are more rational and yield more comprehensive information. The presented data also provide a basis for novel perspectives regarding certain inflammatory conditions.
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| 8. |
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| 9. |
- Jansson, Britt, et al.
(författare)
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Simultaneous enantiospecific separation and quantitation of mephenytoin and its metabolites nirvanol and 4'-hydroxymephenytoin in human plasma by liquid chromatography.
- 2003
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Ingår i: Journal of chromatography. B, Analytical technologies in the biomedical and life sciences. - 1570-0232 .- 1873-376X. ; 791:1-2, s. 179-91
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Tidskriftsartikel (refereegranskat)abstract
- A high-performance liquid chromatographic method for the enantiospecific quantitation of S- and R-mephenytoin and its metabolites S- and R-nirvanol and S- and R-4'-hydroxymephenytoin in plasma is described. The compounds were separated using a reversed-phase C(2) column in tandem with a chiral alpha(1)-acid glycoprotein column and were detected using ultraviolet detection at 205 nm. The lower limit of quantification was 10 ng/ml for all compounds using 0.5 ml human plasma (intra-day coefficient of variation <13%, accuracy <+/-20%). The method was validated for human plasma in the concentration range 10-2000 ng/ml for each of the six compounds. The method allows for the simultaneous characterisation of the metabolic capacity of two human drug-metabolising enzymes, CYP2C19 and CYP2B6, and may be used when investigating polymorphisms or changes in activity of these two enzymes.
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| 10. |
- Lutz, Mareike, 1967-, et al.
(författare)
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Monolithic silica rod liquid chromatography with ultraviolet or fluorescence detection for metabolite analysis of cytochrome P450 marker reactions
- 2002
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Ingår i: Journal of chromatography. B. - Amsterdam : Elsevier. - 1570-0232 .- 1873-376X. ; 780:2, s. 205-215
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Tidskriftsartikel (refereegranskat)abstract
- In vitro cytochrome P450 assays are used in metabolism studies in support of early phases of drug discovery to investigate, e.g., metabolic stability, enzyme inhibition and induction by new chemical entities. LC-UV and LC-fluorescence are traditional analytical tools in support of such studies. However, these tools typically comprise different methods of relatively low throughput for the various metabolites of probe reactions. In recent years, LC-MS methods have been developed to increase throughput. Increased throughput can also be achieved by means of modern chromatographic tools in combination with UV and fluorescence detection. This approach is especially suitable when cytochrome P450 isoforms are investigated by means of single probe incubations. Here, an LC-UV/fluorescence system based on a monolithic porous silica column is described for the analysis of metabolites of nine cytochrome P450 marker reactions [phenacetin to paracetamol (CYP1A2), coumarin to 7-hydroxycoumarin (CYP2A6), paclitaxel to 6alpha-hydroxypaclitaxel (CYP2C8), diclofenac to 4-hydroxydiclofenac (CYP2C9), mephenytoin to 4-hydroxymephenytoin (CYP2C19), bufuralol to 1-hydroxybufuralol (CYP2D6), chlorzoxazone to 6-hydroxychlorzoxazone (CYP2E1), midazolam to 1-hydroxymidazolam (CYP3A4), and testosteron to 6beta-hydroxytestosteron (CYP3A4)]. While offering sensitivities and linear ranges comparable to previously reported methods, the set-up described here provides ease of use and increased throughput with maximum cycle times of 4.5 min. © 2002 Elsevier Science B.V. All rights reserved.
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| 11. |
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| 12. |
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| 13. |
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| 14. |
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| 15. |
- Knutsen Holmqvist, Annica, et al.
(författare)
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Survivin expression is an independent prognostic factor in rectal cancer patients with and without preoperative radiotherapy
- 2004
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Ingår i: Journal of chromatography. B. - 1570-0232 .- 1873-376X. ; 60:1, s. 149-155
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: Survivin, as an inhibitor of apoptosis, is undetectable in normal tissues but expressed in tumors. Survivin expression in rectal cancer patients who have undergone preoperative radiotherapy (RT) alone has not been studied. We analyzed the relationships of survivin expression to RT, clinicopathologic variables, apoptosis, and p53 expression in rectal cancer patients who participated in a trial of preoperative RT. Methods and Materials: Survivin was immunohistochemically examined in 98 rectal tumors (74 had adjacent normal mucosa). Of 98 patients, 57 underwent surgery alone and 41 underwent RT before surgery. Results: Survivin positivity was related to worse survival, independent of Dukes' stage, local and distant recurrence, differentiation, gender, age, apoptosis, and p53 expression (p = 0.02). Survivin was not associated with survival in the patients without (p = 0.08) or with (p = 0.19) RT. After RT, survivin tended to be increased in adjacent normal mucosa (p = 0.057) but not in tumors (p = 0.71). Conclusion: Survivin was independently related to survival in rectal cancer patients who participated in a trial of preoperative RT, but not in either treatment group (surgery alone or surgery plus RT). Whether the effect of survivin on tumors is associated with RT and further related to patient survival needs to be investigated in a larger number of patients. (C) 2004 Elsevier Inc.
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| 16. |
- Abdel–Khalik, Jonas, et al.
(författare)
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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
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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.
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| 17. |
- 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. - : Elsevier BV. - 1570-0232. ; 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.
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| 18. |
- Abdel–Khalik, Jonas, et al.
(författare)
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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
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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.
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| 19. |
- 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. - : Elsevier BV. - 1570-0232. ; 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.
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| 20. |
- Abuzooda, Thana, et al.
(författare)
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Graphite-based microextraction by packed sorbent for online extraction of beta-blockers from human plasma samples
- 2015
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Ingår i: Journal of chromatography. B. - : Elsevier BV. - 1570-0232 .- 1873-376X. ; 992, s. 86-90
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Tidskriftsartikel (refereegranskat)abstract
- In the present work a new graphitic material (Carbon-XCOS) was used as a sorbent for microextraction by packed sorbent (MEPS).The beta-blockers metoprolol and acebutolol in plasma samples were extracted and detected online using Carbon-MEPS syringe and liquid chromatography and tandem mass spectrometry (LC-MS/MS). Factors affecting the MEPS performance such as conditioning, washing and elution solutions were investigated. The validation of the bioanalytical method was performed using human plasma. The standard curve ranged from 10 to 2000 nM and the lower limit of quantification (LLOQ) was set to 10 nM. The method validation showed good accuracy and precision for the quality control (QC) samples at three concentration levels (30, 800 and 1600 nM). The accuracy values of the QC samples were in the range of 86-108% (n = 18). The precision values of intra- and inter-day for QC samples ranged from 4.4% to 14.4% (RSD) for the both studied analytes. The coefficient of determination (R-2) values were >= 0.999 (n = 3).
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| 21. |
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| 22. |
- Ahmadi, Mazaher, et al.
(författare)
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Reduced graphene oxide as an efficient sorbent in microextraction by packed sorbent : Determination of local anesthetics in human plasma and saliva samples utilizing liquid chromatography-tandem mass spectrometry
- 2018
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Ingår i: Journal of chromatography. B. - : ELSEVIER SCIENCE BV. - 1570-0232 .- 1873-376X. ; 1095, s. 177-182
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Tidskriftsartikel (refereegranskat)abstract
- Herein, reduced graphene oxide (RGO) has been utilized as an efficient sorbent in microextraction by packed sorbent (MEPS). The combination of MEPS and liquid chromatography-tandem mass spectrometry has been used to develop a method for the extraction and determination of three local anesthetics (i.e. lidocaine, prilocaine, and ropivacaine) in human plasma and saliva samples. The results showed that the utilization of RGO in MEPS could minimize the matrix effect so that no interfering peaks at the retention times of the analytes or internal standard was observed. The high extraction efficiency of this method was approved by mean recoveries of 97.26-106.83% and 95.21-105.83% for the studied analytes in plasma and saliva samples, respectively. Intra- and inter-day accuracies and precisions for all analytes were in good accordance with the international regulations. The accuracy values (as percentage deviation from the nominal value) of the quality control samples were between - 2.1 to 13.9 for lidocaine, - 4.2 to 11.0 for prilocaine and between - 4.5 to - 2.4 for ropivacaine in plasma samples while the values were ranged from - 4.6 to 1.6 for lidocaine, from - 4.2 to 15.5 for prilocaine and from - 3.3 to - 2.3 for ropivacaine in human saliva samples. Lower and upper limit of quantification (LLOQ, ULOQ) were set at 5 and 2000 nmol L-1 for all of the studied drugs. The correlation coefficients values were >= 0.995. The limit of detection values were obtained 4 nmol L-1 for lidocaine and prilocaine, and 2 nmol L-1 for ropivacaine.
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| 23. |
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| 24. |
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| 25. |
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| 26. |
- Amelina, Hanna, et al.
(författare)
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Quantitative subproteomic analysis of age-related changes in mouse liver peroxisomes by iTRAQ LC-MS/MS
- 2011
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Ingår i: Journal of chromatography. B. - : Elsevier BV. - 1570-0232 .- 1873-376X. ; 879:30, s. 3393-3400
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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.
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| 27. |
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| 28. |
- Anderot, Maria, et al.
(författare)
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Determination of dissociation constants between polyelectrolytes and proteins by affinity capillary electrophoresis
- 2009
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Ingår i: Journal of chromatography. B. - : Elsevier BV. - 1570-0232 .- 1873-376X. ; 877:10, s. 892-896
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Tidskriftsartikel (refereegranskat)abstract
- In this manuscript we report the binding affinity between two model proteins, human serum albumin (HSA) and ribonuclease A (RNase A), and negatively charged polyelectrolytes, two different heparin fractions and dextran sulfate, by means of partial filling and affinity capillary electrophoresis. The apparent dissociation constants, K-d, obtained by use of the partial-filling method, between HSA and heparin (17 kDa), heparin (3 kDa) and dextran sulfate (8 kDa) were 33 and 307 mu M, respectively. A new method was developed to determine affinities that take in account different migration directions between the protein and the polyelectrolyte, which was required to study RNase A. By use of this affinity capillary electrophoresis two K-d values were observed for the interaction between RNase A and heparin 17 kDa, yielding a high affinity binding with K-d1 0.0075 mu M, and a lower affinity binding with K-d2 8.7 mu M. For dextran sulfate 8 kDa these K-d values were 0.027 and 10.4 mu M, respectively. Heparin 3 kDa only showed a single K-d value of 0.52 mu M. The results show that the magnitude of the binding affinity depends on the type of polyelectrolyte and its molecular weight. (C) 2009 Elsevier B.V. All rights reserved.
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| 29. |
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| 30. |
- Arvidsson, Björn, et al.
(författare)
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Online capillary solid phase extraction and liquid chromatographic separation with quantitative tandem mass spectrometric detection (SPE-LC-MS/MS) of ximelagatran and its metabolites in a complex matrix.
- 2009
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Ingår i: Journal of chromatography. B. - : Elsevier BV. - 1570-0232 .- 1873-376X. ; 877:3, s. 291-297
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Tidskriftsartikel (refereegranskat)abstract
- This work presents the development and validation of a fully automated quantitative analysis method of melagatran, its prodrug ximelagatran, and its major metabolites for the study of drug behavior in biofluids. The method involves online sample clean-up and enrichment on a C4 capillary column followed by separation on a capillary C18 column. Electrospray ionization tandem mass spectrometric detection in positive ion mode was performed with multiple reactions monitoring of eight different transients, divided into two time segments with four transients each. The structural similarity, the complexity of the matrix (pig liver extract) and the formation of isobaric fragment ions, made efficient chromatographic separation necessary. The analysis method provides valid accuracy (<9%; RSD%), precision (<8%; RSD%), linearity (<1.2 nM–1 μM; R2 > 0.999), limit of quantitation (<3.6 nM), retention repeatability (<1.2%; RSD%), selectivity, as well as analyte and column stabilities over a wide concentration range.
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| 31. |
- Asliyuce Coban, Sevgi, et al.
(författare)
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Synthesis and use of protein G imprinted cryogel as affinity matrix to purify protein G from cell lyaste.
- 2016
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Ingår i: Journal of Chromatography. B. - : Elsevier BV. - 1873-376X .- 1570-0232. ; 1021, s. 204-212
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Tidskriftsartikel (refereegranskat)abstract
- Monolithic macroporous cryogel imprinted with protein G was prepared using a functional co-monomer of N-methacryloyl-l-phenylalanine and 2-hydroxyethyl methacrylate. The chemical structure of the cryogel prepared was studied by FTIR-spectroscopy and its porosity was analysed using scanning electron microscopy. The cryogel was used to purify protein G from recombinant Escherichia coli cell lysate and the effect of pH, temperature, ionic strength, flow rate, etc on the adsorption of protein G to the monolithic column have been investigated. The selectivity of the imprinted cryogel was studied using protein A and myoglobin. It was possible to capture about 9mg of Protein G per g of the cryogel.
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| 32. |
- Aziz, Mohd Yusmaidie, 1984, et al.
(författare)
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LC-MS/MS quantitation of antimalarial drug piperaquine and metabolites in human plasma
- 2017
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Ingår i: Journal of chromatography. B. - : Elsevier BV. - 1570-0232. ; 1063, s. 253-258
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: This study aimed to develop a sensitive, quantitative assay for the antimalarial piperaquine (PQ) and its metabolites M1 and M2 in human plasma. Results: Analytes were gradiently separated on a C18 column and detected with a Sciex API 4000 MS/MS with an ESI source operated in the positive ion mode with deuterated PQ as internal standard. The response was linear in the range 3.9-2508 nM with a runtime of 7.0 min per sample. The method was applied to clinical samples from healthy volunteers. Conclusion: This LC-MS/MS method for the simultaneous quantitation of PQ and two of its metabolites in plasma may prove helpful for assessment of metabolite safety issues in vivo.
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| 33. |
- Bankefors, Johan, et al.
(författare)
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Multidimensional profiling of components in complex mixtures of natural products for metabolic analysis, proof of concept: Application to Quillaja saponins
- 2010
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Ingår i: Journal of Chromatography B. - : Elsevier BV. - 1570-0232 .- 1873-376X. ; 878, s. 471-476
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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.
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| 34. |
- Baranowska, Irena, et al.
(författare)
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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
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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.
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| 35. |
- Baranowska, Irena, et al.
(författare)
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UHPLC method for the simultaneous determination of beta-blockers, isoflavones and their metabolites in human urine
- 2011
-
Ingår i: JOURNAL OF CHROMATOGRAPHY B-ANALYTICAL TECHNOLOGIES IN THE BIOMEDICAL AND LIFE SCIENCES. - : Elsevier Science B.V., Amsterdam.. - 1570-0232. ; 879:9-10, s. 615-626
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Tidskriftsartikel (refereegranskat)abstract
- A rapid-resolution ultra high-performance liquid chromatography separation method (UHPLC) for the simultaneous determination of the following beta-blockers: milrinone, sotalol, metoprolol, propranolol and carvedilol, and their metabolites: 5-hydroxylphenyl-carvedilol, O-desmethylcarvedilol, 4-hydroxypropranolol, alpha-hydroxy-metoprolol, O-desmethyl-metoprolol; the following isoflavones: genistein, daidzein, glycitin, glycitein, puerarin and biochanin A; as well as their metabolites: dihydrogenistein, desmethylglycitein, 8-hydroxygenistein, daidzein-7,4-diglucoside, 8-hydroxydaidzein, dihydrobiochanin A in human urine was optimized. The analysed compounds were extracted from human urine by means of solid phase extraction (SPE). The effective UHPLC separation of the examined compounds was applied on a Hypersil GOLD (TM) (50 mm x 2.1 mm, 1.9 mu m) column with a gradient mobile phase system and a UV detector. The complete separation of all analytes was achieved within 8.0 min. The method was validated for the determination of the aforementioned substances in human urine. The linear ranges, limits of detection CLOD) and limits of quantification (LOQ) for beta-blockers, isoflavones and their metabolites were determined. The intra- and inter-day precision (%C.V.) was less than 4.48%, and the intra-day and inter-day accuracy was less than 4.74%. The tested SPE sorbent proved that appropriate absolute recoveries can be obtained for Oasis HLB (Waters). The mean recovery of the analytes, using the new SPE procedure, amounted from 70.14% to 99.85%. The present paper reports, for the first time, the method for the determination of beta-blockers, isoflavones and their metabolites in human urine samples. The newly developed method was suitably validated and successfully applied for the analysis of the certain of the aforementioned analytes in human urine samples obtained from the patients suffering cardiovascular disease.
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| 36. |
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| 37. |
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| 38. |
- Bennemo, Mia, et al.
(författare)
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A chromatographic method for determination of supercoiled plasmid DNA concentration in complex solutions.
- 2009
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Ingår i: Journal of chromatography. B. - : Elsevier BV. - 1570-0232 .- 1873-376X. ; 877:24, s. 2530-6
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Tidskriftsartikel (refereegranskat)abstract
- A method for determination of the plasmid DNA concentration with subsequent analysis of the ratio supercoiled to open circular form is presented. The method is suitable for samples from all steps of the manufacturing process, from fermentation to final product. The analysis consists of size exclusion chromatography, followed by analytical thiophilic aromatic chromatography. In the first step, the plasmid DNA concentration is determined by group separation, including removal of RNA and other impurities, within less than 2 min. The limit of detection and quantification was 0.28 and 0.83 microg/ml, respectively. The precision of the method is high, providing a coefficient of variation as low as below 2%. In the second step, the ratio of open circular to supercoiled plasmid DNA is determined following separation of the two plasmid DNA isoforms with a linear salt gradient. The precision of the second step was evaluated using serial injections of aliquots of a sample stock solution. In comparison with the two most commonly used methods, the developed analysis was found to be significantly more accurate than agarose gel electrophoresis and equivalent to capillary gel electrophoresis. The combined methods for quantification and control of homogeneity of plasmid DNA presented here enable reliable and precise analysis at all steps of the manufacturing process.
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| 39. |
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| 40. |
- Bergström, Maria, et al.
(författare)
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Elucidating the selectivity of recombinant forms of Aleuria aurantia lectin using weak affinity chromatography
- 2012
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Ingår i: Journal of chromatography. B. - : Elsevier. - 1570-0232 .- 1873-376X. ; 885, s. 66-72
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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.
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| 41. |
- Bergström, Maria, et al.
(författare)
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Lectin affinity capillary electrophoresis in glycoform analysis applying the partial filling technique
- 2004
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Ingår i: Journal of chromatography. B. - : Elsevier BV. - 1570-0232 .- 1873-376X. ; 809:2, s. 323-329
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Tidskriftsartikel (refereegranskat)abstract
- The study of protein glycosylation and its significance in biological interactions is a field of growing interest. This work demonstrates a lectin-based separation of protein glycoforms of α1-acid glycoprotein (AGP or orosomucoid) with capillary electrophoresis. Glycoform analysis was performed with a "partial filling technique" with the lectin Concanavalin A (Con A) as affinity ligand. Con A separated human AGP into two peaks, the first peak included AGP glycoforms without biantennary glycans, and the second peak represented the fraction that had one or more biantennary glycans. The applicability of the method was demonstrated with the analysis of AGP from clinical samples and AGP treated with N-glycosidase F. The AGP separation was also used as a reporter system to estimate the dissociation constant (KD) between Con A and a competing sugar. © 2004 Elsevier B.V. All rights reserved.
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| 42. |
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| 43. |
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| 44. |
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| 45. |
- Boström, Tove, et al.
(författare)
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Antibodies as means for selective mass spectrometry
- 2016
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Ingår i: Journal of chromatography. B. - : Elsevier. - 1570-0232 .- 1873-376X. ; 1021, s. 3-13
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Tidskriftsartikel (refereegranskat)abstract
- For protein analysis of biological samples, two major strategies are used today; mass spectrometry (MS) and antibody-based methods. Each strategy offers advantages and drawbacks. However, combining the two using an immunoenrichment step with MS analysis brings together the benefits of each method resulting in increased sensitivity, faster analysis and possibility of higher degrees of multiplexing. The immunoenrichment can be performed either on protein or peptide level and quantification standards can be added in order to enable determination of the absolute protein concentration in the sample. The combination of immunoenrichment and MS holds great promise for the future in both proteomics and clinical diagnostics. This review describes different setups of immunoenrichment coupled to mass spectrometry and how these can be utilized in various applications.
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| 46. |
- Carlsson, Björn, et al.
(författare)
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Solid-phase extraction with end-capped C2 columns for the routine measurement of racemic citalopram and metabolites in plasma by high-performance liquid chromatography
- 1997
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Ingår i: Journal of Chromatography B: Biomedical Sciences and Applications. - 1570-0232. ; 702:1-2, s. 234-239
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Tidskriftsartikel (refereegranskat)abstract
- An assay based on solid-phase extraction followed by high-performance liquid chromatography (HPLC) was developed for the measurement of citalopram and its main metabolites desmethylcitalopram and didesmethylcitalopram. The best extraction procedure was performed with end-capped C2 column utilising secondary silanol interactions to obtain clean extract. The HPLC analysis was done on a phenyl column with a mobile phase without any amine additives. Fluorescence detection gave a limit of detection of 0.8 nmol/l plasma for the compounds analysed.
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| 47. |
- Carlsson, Henrik, 1987-, et al.
(författare)
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Evaluation of polarity switching for untargeted lipidomics using liquid chromatography coupled to high resolution mass spectrometry
- 2022
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Ingår i: Journal of chromatography. B. - : Elsevier. - 1570-0232 .- 1873-376X. ; 1195
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Tidskriftsartikel (refereegranskat)abstract
- Untargeted lipidomics using liquid chromatography high-resolution mass spectrometry (LC-HRMS) was performed using polarity switching, and in positive and negative polarity separately on the same set of serum samples, and the performances of the methods were evaluated.& nbsp;Polarity switching causes an increase in the cycle time of the HRMS measurements (1.18 s/cycle vs 0.27 s/ cycle), resulting in fewer data points across chromatographic peaks. The coefficient of variation (CV) was on average lower for the added isotopically labelled standards in pooled samples (QC) and patient samples using separate polarities (QC = 5.6%, samples = 12.5%) compared to polarity switching (QC = 8.5%, samples = 13.4%), but the difference was not statistically significant. For the endogenous features measured in the QCs polarity switching resulted in on average significantly higher CVs (3.80 (p = 4.25e-30) and 3.3 percentage points (p = 6.84e-40), for positive and negative modes, respectively) however still acceptable for an untargeted method (mean CVs of 17.9% and 12.2% in positive and negative modes respectively). A slightly larger number of endogenous features were detected using the separate polarities, but the large majority of features (> 95%) were detected with both methodologies. The overlap of features detected in both positive and negative polarities was low (4.1%) demonstrating the importance of using both polarities for untargeted lipidomics. When investigating the effects of a treatment on multiple sclerosis patients it was found that both methodologies gave highly similar biological results, further confirming the applicability of polarity switching.
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| 48. |
- Casas, Monica Escolà, et al.
(författare)
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Analytical sample preparation strategies for the determination of antimalarial drugs in human whole blood, plasma and urine
- 2014
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Ingår i: Journal of chromatography. B. - 1570-0232 .- 1873-376X. ; 962, s. 109-131
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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
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| 49. |
- Casas, Monica Escolà, et al.
(författare)
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Analytical sample preparation strategies for the determination of antimalarial drugs in human whole blood, plasma and urine
- 2014
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Ingår i: Journal of chromatography. B. - : Elsevier BV. - 1570-0232. ; 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
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| 50. |
- Chadt, J, et al.
(författare)
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Monitoring of dimethyl sulphate-induced N3-methyladenine, N7-methylguanine and O6-methylguanine DNA adducts using reversed-phase high performance liquid chromatography and mass spectrometry
- 2008
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Ingår i: Journal of chromatography. B. - : Elsevier BV. - 1570-0232 .- 1873-376X. ; 867, s. 43-48
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Tidskriftsartikel (refereegranskat)abstract
- This work describes the determination of N3-methyladenine, N7-methylguanine and O6-methylguanine adducts in dimethyl sulphate-treated salmon-testes DNA employing reversed-phase high performance liquid chromatography (RP-HPLC) with UV–vis detection, followed by mass-spectrometric verification using electrospray ionisation in positive mode ESI(+). Within validation parameters, accuracy, precision, calibration parameters, limit of detection (LOD) and quantitation (LOQ) as well as stability of standard stock solutions were tested and presented for UV/vis detection. The limit of detection (LOD) was found to be 0.1 ng/mL for N3-methyladenine and 0.2 ng/mL for both N7-methylguanine and O6-methylguanine (S/N = 3). The limit of quantitation (LOQ) was found to be 0.5 ng/mL for all measured compounds, (S/N = 10). Quantitative results were obtained for each substance based on eight-point calibration. Intra- and inter-day precisions were within 1.73–6.96 and 2.26–7.58%, respectively, and correlation coefficients of calibration curves (R2) ranged from 0.9992 to 0.9997. Relative proportion of N7-methylguanine was accounted for 61.53 ± 2.97% (R.S.D. = 4.8), N3-methyladenine for 38.19 ± 2.99% (R.S.D. = 9.6) and O6-methylguanine for 0.29 ± 0.02% (R.S.D. = 5.1), respectively. The application of the above-mentioned techniques provides a valuable contribution for simultaneous determination of methylated DNA adducts, and may represent a suitable approach for similar monitoring/screening studies.
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