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| 2. |
- Petersson, Patrik, et al.
(författare)
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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
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Ingår i: Journal of chromatography. B. - : Elsevier BV. - 1570-0232 .- 1873-376X .- 0021-9673 .- 1873-3778. ; 1218:39, s. 6914-6921
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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.
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| 5. |
- 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
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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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| 6. |
- 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
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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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| 7. |
- 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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| 9. |
- Adielsson, A., et al.
(författare)
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Changes over time in 30-day survival and the incidence of shockable rhythms after in-hospital cardiac arrest- A population-based registry study of nearly 24,000 cases
- 2020
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Ingår i: Resuscitation. - : Elsevier BV. - 0300-9572 .- 1873-1570. ; 157, s. 135-140
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To determine changes over time in 30-day survival and the incidence of shockable rhythms after in-hospital cardiac arrest, from a countrywide perspective. Methods: Patient information from the Swedish Registry for Cardiopulmonary Resuscitation was analysed in relation to monitoring level of ward and initial rhythm. The primary outcome was defined as survival at 30 days. Changes in survival and incidence of shockable rhythms were reported per year from 2008 to 2018. Also, epidemiological data were compared between two time periods, 2008-2013 and 2014-2018. Results: In all, 23,186 unique patients (38.6% female) were included in the study. The mean age was 72.6 (SD 13.2) years. Adjusted trends indicated an overall increase in 30-day survival from 24.7% in 2008 to 32.5% in 2018, (on monitoring wards from 32.5% to 43.1% and on non-monitoring wards from 17.6% to 23.1%). The proportion of patients found in shockable rhythms decreased overall from 31.6% in 2008 to 23.6% in 2018, (on monitoring wards from 42.5% to 35.8 % and on non-monitoring wards from 20.1% to 12.9%). Among the patients found in shockable rhythms, the proportion of patients defibrillated before the arrival of cardiac arrest team increased from 71.0% to 80.9%. Conclusions: In an 11-year perspective, resuscitation in in-hospital cardiac arrest in Sweden was characterised by an overall increase in the adjusted 30-day survival, despite a decrease in shockable rhythms. An increased proportion, among the patients found in a shockable rhythm, who were defibrillated before the arrival of a cardiac arrest team may have contributed to the finding.
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| 10. |
- af Geijerstam, Peder, 1983-, et al.
(författare)
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Potential organ donors after Out-of-Hospital Cardiac Arrest during a ten-year period in Stockholm, Sweden
- 2019
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Ingår i: Resuscitation. - Amsterdam, Netherlands : Elsevier. - 0300-9572 .- 1873-1570. ; 137, s. 215-220
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Tidskriftsartikel (refereegranskat)abstract
- Background:Donation after brain death (DBD) is current praxis in Sweden. Circulatory death is far more common. Donation from patients suffering Out-of-Hospital Cardiac Arrest (OHCA) may have the potential to increase the organ-donor pool. The aim of this study was to describe the potential donor pool and its characteristics if uncontrolled donation after circulatory death (uDCD) were to be implemented in the metropolitan area of Stockholm, Sweden.Methods:A retrospective analysis was made using data from the Swedish Register for cardiopulmonary resuscitation (SRCR) between 2006 and 2015. Evaluation of potential organ donors was made using selection criteria from five previously published protocols concerning uDCD.Results:When applying different criteria from each of the five studied protocols in a total of 9,793 cases of OHCA, between 7.5% (n = 732) and 1.5% (n = 150) of the patients were found to be potential candidates for uDCD. The median age of the sampled uDCD candidates in each protocol was between 48 and 57 years. Male donors were found in 67–76% of all cases.Conclusion:Although not taking important real-life limitations into account, our results indicate that implementation of a uDCD programme may substantially increase the number of potential organ donors in Stockholm.
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