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Leal FG, de Andrade Ferreira A, Silva GM, Freire TA, Costa MR, de Morais ET, Guzzo JVP, de Oliveira EC. Measurement Uncertainty and Risk of False Compliance Assessment Applied to Carbon Isotopic Analyses in Natural Gas Exploratory Evaluation. Molecules 2024; 29:3065. [PMID: 38999016 PMCID: PMC11243181 DOI: 10.3390/molecules29133065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2024] [Revised: 06/22/2024] [Accepted: 06/25/2024] [Indexed: 07/14/2024] Open
Abstract
The concept of uncertainty in an isotopic analysis is not uniform in the scientific community worldwide and can compromise the risk of false compliance assessment applied to carbon isotopic analyses in natural gas exploratory evaluation. In this work, we demonstrated a way to calculate one of the main sources of this uncertainty, which is underestimated in most studies focusing on gas analysis: the δ13C calculation itself is primarily based on the raw analytical data. The carbon isotopic composition of methane, ethane, propane, and CO2 was measured. After a detailed mathematical treatment, the corresponding expanded uncertainties for each analyte were calculated. Next, for the systematic isotopic characterization of the two gas standards, we calculated the standard uncertainty, intermediary precision, combined standard uncertainty, and finally, the expanded uncertainty for methane, ethane, propane, and CO2. We have found an expanded uncertainty value of 1.8‰ for all compounds, except for propane, where a value of 1.6‰ was obtained. The expanded uncertainty values calculated with the approach shown in this study reveal that the error arising from the application of delta calculation algorithms cannot be neglected, and the obtained values are higher than 0.5‰, usually considered as the accepted uncertainty associated with the GC-IRMS analyses. Finally, based on the use of uncertainty information to evaluate the risk of false compliance, the lower and upper acceptance limits for the carbon isotopic analysis of methane in natural gas are calculated, considering the exploratory limits between -55‰ and -50‰: (i) for the underestimated current uncertainty of 0.5‰, the lower and upper acceptance limits, respectively, are -54.6‰ and -50.4‰; and (ii) for the proposed realistic uncertainty of 1.8‰, the lower and upper acceptance limits would be more restrictive; i.e., -53.5‰ and -51.5‰, respectively.
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Affiliation(s)
- Fabiano Galdino Leal
- Research Center, Petrobras S.A., Rio de Janeiro 21941-915, Brazil; (F.G.L.); (A.d.A.F.); (T.A.F.); (M.R.C.); (E.T.d.M.); (J.V.P.G.)
| | - Alexandre de Andrade Ferreira
- Research Center, Petrobras S.A., Rio de Janeiro 21941-915, Brazil; (F.G.L.); (A.d.A.F.); (T.A.F.); (M.R.C.); (E.T.d.M.); (J.V.P.G.)
| | - Gabriel Moraes Silva
- Center for Energy Resources Engineering, Department of Chemical and Biochemical Engineering, Technical University of Denmark, 2800 Kongens Lyngby, Denmark;
| | - Tulio Alves Freire
- Research Center, Petrobras S.A., Rio de Janeiro 21941-915, Brazil; (F.G.L.); (A.d.A.F.); (T.A.F.); (M.R.C.); (E.T.d.M.); (J.V.P.G.)
| | - Marcelo Ribeiro Costa
- Research Center, Petrobras S.A., Rio de Janeiro 21941-915, Brazil; (F.G.L.); (A.d.A.F.); (T.A.F.); (M.R.C.); (E.T.d.M.); (J.V.P.G.)
| | - Erica Tavares de Morais
- Research Center, Petrobras S.A., Rio de Janeiro 21941-915, Brazil; (F.G.L.); (A.d.A.F.); (T.A.F.); (M.R.C.); (E.T.d.M.); (J.V.P.G.)
| | - Jarbas Vicente Poley Guzzo
- Research Center, Petrobras S.A., Rio de Janeiro 21941-915, Brazil; (F.G.L.); (A.d.A.F.); (T.A.F.); (M.R.C.); (E.T.d.M.); (J.V.P.G.)
| | - Elcio Cruz de Oliveira
- Postgraduate Programme in Metrology, Pontifical Catholic University of Rio de Janeiro, Rio de Janeiro 22451-900, Brazil
- Land Transportation and Storage, Measurement and Product Inventory Management, Logistics, Petrobras S.A., Rio de Janeiro 20231-030, Brazil
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Identification of endogenous and exogenous semicarbazide (SEM) in crustacea aquatic products using compound-specific nitrogen stable isotope ratio analysis (NSIRA). J Food Compost Anal 2023. [DOI: 10.1016/j.jfca.2023.105257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/05/2023]
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Munar A, Clinton Frazee C, Garg U. Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) Method for the Quantification of Steroids Androstenedione, Dehydroepiandrosterone, 11-Deoxycortisol, 17-Hydroxyprogesterone, and Testosterone. Methods Mol Biol 2022; 2546:451-457. [PMID: 36127612 DOI: 10.1007/978-1-0716-2565-1_40] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
Abstract
Congenital adrenal hyperplasia (CAH) is a group of autosomal-recessive disorders due to deficiency of 11- or 21-hydroxylase. The analysis of cortisol, androstenedione, 17-hydroxyprogesterone (OHPG), dehydroepiandrosterone (DHEA), 11-deoxycortisol, and testosterone is generally performed in the diagnosis and/or follow-up of CAH. Analysis of specific steroids is also performed in other disorders such as evaluation of hirsutism or infertility in females and hypogonadism in males. Cortisol is generally analyzed by immunoassays, whereas other hormones are preferably assayed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). A multiple reaction monitoring, positive mode atmospheric pressure chemical ionization, LC-MS/MS method is described for the simultaneous quantification of androstenedione, 17-hydroxyprogesterone, DHEA, 11-deoxycortisol and testosterone. The method involves addition of labeled internal standards to serum samples and extraction of steroids in methyl tert-butyl ether. The extract is evaporated under stream of nitrogen, and the residue is reconstituted in methanol and analyzed by LC-MS/MS.
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Affiliation(s)
- Ada Munar
- Department of Pathology and Laboratory Medicine, Children's Mercy Hospital, Kansas City, MO, USA
| | - C Clinton Frazee
- Department of Pathology and Laboratory Medicine, Children's Mercy Hospital, Kansas City, MO, USA
| | - Uttam Garg
- Department of Pathology and Laboratory Medicine, Children's Mercy Hospital, Kansas City, MO, USA.
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Wang Y, Liu T, Chen F, Wang X, Zhang F. Determination of exogenous prohibited flavour compounds added in coffee using gas chromatography triple quadrupole tandem massspectrometry and gas chromatography/combustion/isotope ratio mass spectrometry. Food Addit Contam Part A Chem Anal Control Expo Risk Assess 2020; 37:2011-2022. [PMID: 33151806 DOI: 10.1080/19440049.2020.1831081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
An analytical method based on gas chromatography coupled to triple quadrupole tandem mass spectrometry (GC-MS/MS) was developed for the simultaneous determination of exogenous prohibited flavour compounds in coffee samples. In addition, gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) was developed to determine the origin of the founded prohibited flavour compound, N-methylpyrrole-2-carboxaldehyde (NMPCA). The good selectivity and sensitivity achieved in multiple reactions monitoring (MRM) mode allowed satisfactory confirmation and quantitation for the flavour compounds. The limits of detection (LODs) and limits of quantitation (LOQs) of these compounds were in the range of 0.0005-5.0 µg/kg and 0.002-16.0 µg/kg, respectively. The coffee samples were extracted with simultaneous distillation extraction (SDE) and NMPCA was analysed on a GC/C/IRMS system. The δ13C values of endogenous NMPCA in coffee beans were within a range of -35.0‰ to -31.1‰, whereas exogenous NMPCA was the range from -27.9‰ to -23.9‰. The validation results revealed that the GC-MS/MS method was sensitive and reliable, and the origin of NMPCA can be distinguished by GC/C/IRMS. Finally, this method was successfully applied to coffee samples analysis and NMPCA was found in coffee samples.
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Affiliation(s)
- Yujiao Wang
- Institute of Food Safety, Chinese Academy of Inspection & Quarantine , Beijing, China.,School of Bioengineering, Tianjin University of Science & Technology , Tianjin, China
| | - Tong Liu
- Institute of Food Safety, Chinese Academy of Inspection & Quarantine , Beijing, China
| | - Fengming Chen
- Institute of Food Safety, Chinese Academy of Inspection & Quarantine , Beijing, China
| | - Xiujuan Wang
- Institute of Food Safety, Chinese Academy of Inspection & Quarantine , Beijing, China
| | - Feng Zhang
- Institute of Food Safety, Chinese Academy of Inspection & Quarantine , Beijing, China
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Li L, Liu K, Fang D. Single Cell Electrochemiluminescence Analysis of Cholesterol in Plasma Membrane during Testosterone Treatment. ELECTROANAL 2020. [DOI: 10.1002/elan.201900561] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Linyu Li
- School of Pharmacy and Key Laboratory of Targeted Intervention of Cardiovascular Disease, Collaborative Innovation Center for Cardiovascular Disease Translational Medicine Nanjing Medical University Nanjing, Jiangsu 211126 China
- Department of Pharmacy, Huashan Hospital Fudan University Shanghai 200040 China
| | - Kang Liu
- School of Pharmacy and Key Laboratory of Targeted Intervention of Cardiovascular Disease, Collaborative Innovation Center for Cardiovascular Disease Translational Medicine Nanjing Medical University Nanjing, Jiangsu 211126 China
| | - Danjun Fang
- School of Pharmacy and Key Laboratory of Targeted Intervention of Cardiovascular Disease, Collaborative Innovation Center for Cardiovascular Disease Translational Medicine Nanjing Medical University Nanjing, Jiangsu 211126 China
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Cunsolo V, Foti S, Ner‐Kluza J, Drabik A, Silberring J, Muccilli V, Saletti R, Pawlak K, Harwood E, Yu F, Ciborowski P, Anczkiewicz R, Altweg K, Spoto G, Pawlaczyk A, Szynkowska MI, Smoluch M, Kwiatkowska D. Mass Spectrometry Applications. Mass Spectrom (Tokyo) 2019. [DOI: 10.1002/9781119377368.ch8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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Holden NE, Coplen TB, Böhlke JK, Tarbox LV, Benefield J, de Laeter JR, Mahaffy PG, O’Connor G, Roth E, Tepper DH, Walczyk T, Wieser ME, Yoneda S. IUPAC Periodic Table of the Elements and Isotopes (IPTEI) for the Education Community (IUPAC Technical Report). PURE APPL CHEM 2018. [DOI: 10.1515/pac-2015-0703] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Abstract
The IUPAC (International Union of Pure and Applied Chemistry) Periodic Table of the Elements and Isotopes (IPTEI) was created to familiarize students, teachers, and non-professionals with the existence and importance of isotopes of the chemical elements. The IPTEI is modeled on the familiar Periodic Table of the Chemical Elements. The IPTEI is intended to hang on the walls of chemistry laboratories and classrooms. Each cell of the IPTEI provides the chemical name, symbol, atomic number, and standard atomic weight of an element. Color-coded pie charts in each element cell display the stable isotopes and the relatively long-lived radioactive isotopes having characteristic terrestrial isotopic compositions that determine the standard atomic weight of each element. The background color scheme of cells categorizes the 118 elements into four groups: (1) white indicates the element has no standard atomic weight, (2) blue indicates the element has only one isotope that is used to determine its standard atomic weight, which is given as a single value with an uncertainty, (3) yellow indicates the element has two or more isotopes that are used to determine its standard atomic weight, which is given as a single value with an uncertainty, and (4) pink indicates the element has a well-documented variation in its atomic weight, and the standard atomic weight is expressed as an interval. An element-by-element review accompanies the IPTEI and includes a chart of all known stable and radioactive isotopes for each element. Practical applications of isotopic measurements and technologies are included for the following fields: forensic science, geochronology, Earth-system sciences, environmental science, and human health sciences, including medical diagnosis and treatment.
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Affiliation(s)
- Norman E. Holden
- National Nuclear Data Center, Brookhaven National Laboratory , Upton, NY , USA
| | | | | | | | | | | | | | | | - Etienne Roth
- Commissariat à l’énergie atomique (CEA) , Gif-sur-Yvette, France
| | | | - Thomas Walczyk
- Department of Chemistry , National University of Singapore , Singapore , Singapore
| | - Michael E. Wieser
- Department of Physics and Astronomy , University of Calgary , Calgary , Canada
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Feng G, Sun Y, Liu S, Song F, Pi Z, Liu Z. Stepwise targeted matching strategy from in vitro to in vivo based on ultra-high performance liquid chromatography tandem mass spectrometry technology to quickly identify and screen pharmacodynamic constituents. Talanta 2018; 194:619-626. [PMID: 30609581 DOI: 10.1016/j.talanta.2018.10.074] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Revised: 09/13/2018] [Accepted: 10/22/2018] [Indexed: 12/23/2022]
Abstract
The study of in vivo pharmacodynamic constituents (PCs) of traditional Chinese medicine (TCM) is important for providing new clues for TCM applications in clinical therapies in modern medicine. However, detecting and identifying PCs from complex biological samples remain a challenge. In this study, a practical and novel stepwise targeted matching and longitudinal analysis strategy from in vitro to in vivo was developed. This strategy combined with ultra-high performance liquid chromatography tandem mass spectrometry was applied to quickly discover PCs in TCM. This approach was developed based on a core perception that all drugs taken orally might be transformed progressively and orderly from the intestinal tract, liver, and blood to the target organ. Based on this core perception, stepwise targeted matching was orderly and efficiently accomplished by multiple screening processes that were based on a stepwise enriched in-house library. Ginseng (Panax ginseng) was set as the example of herbal medicine for validating the reliability and availability of this approach. By applying this novel strategy to the stepwise screening of metabolites, we successfully identified 113 metabolites, among which 59 compounds were defined as prototypes. Based on the in vivo metabolites, network pharmacology analysis was applied to screen the PCs of ginseng and clarified the action mechanism of ginseng for the treatment of Alzheimer's disease (AD). A total of 27 herbal constituents and 64 related targets shared commonly by compounds and AD were integrated via target network pharmacology analysis. These results demonstrated that this original approach will greatly improve high-throughput screening of metabolites and PCs on AD. It also can explicate the mechanism of action of TCM. Furthermore, this strategy is practicable to identify metabolites and screen PCs in other herbal medicines.
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Affiliation(s)
- Guifang Feng
- State Key Laboratory of Electroanalytical Chemistry, National Center of Mass Spectrometry in Changchun, Jilin Province Key Laboratory of Chinese Medicine Chemistry and Mass Spectrometry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China; University of Science and Technology of China, Hefei 230026, China
| | - Yufei Sun
- State Key Laboratory of Electroanalytical Chemistry, National Center of Mass Spectrometry in Changchun, Jilin Province Key Laboratory of Chinese Medicine Chemistry and Mass Spectrometry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China; University of Science and Technology of China, Hefei 230026, China
| | - Shu Liu
- State Key Laboratory of Electroanalytical Chemistry, National Center of Mass Spectrometry in Changchun, Jilin Province Key Laboratory of Chinese Medicine Chemistry and Mass Spectrometry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China.
| | - Fengrui Song
- State Key Laboratory of Electroanalytical Chemistry, National Center of Mass Spectrometry in Changchun, Jilin Province Key Laboratory of Chinese Medicine Chemistry and Mass Spectrometry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
| | - Zifeng Pi
- State Key Laboratory of Electroanalytical Chemistry, National Center of Mass Spectrometry in Changchun, Jilin Province Key Laboratory of Chinese Medicine Chemistry and Mass Spectrometry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
| | - Zhiqiang Liu
- State Key Laboratory of Electroanalytical Chemistry, National Center of Mass Spectrometry in Changchun, Jilin Province Key Laboratory of Chinese Medicine Chemistry and Mass Spectrometry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China.
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Woźniak B, Matraszek-Żuchowska I, Witek S, Posyniak A. Development of LC-MS/MS Confirmatory Method for the Determination of Testosterone in Bovine Serum. J Vet Res 2017; 61:81-89. [PMID: 29978058 PMCID: PMC5894415 DOI: 10.1515/jvetres-2017-0010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Accepted: 03/10/2017] [Indexed: 11/25/2022] Open
Abstract
Introduction In the European Union the use of steroid growth promoters is prohibited under Council Directive 96/22/EC. For effective control of illegal use of natural steroids, highly sensitive analytical methods are required, because sex hormones can be present in very low concentrations in biological samples. The aim of the study was to develop a confirmatory method for the detection of testosterone in bovine serum at ppt level. Material and Methods 17β-testosterone and internal standards of 17%-testosterone-d2 were extracted from serum samples with a mixture of tert-butyl methyl ether/petroleum ether and were directly analysed by an LC/MS/MS on QTRAP 5500 instrument with a TurboIon-Spray source operating in a positive ionisation mode. Chromatographic separation was achieved on the analytical column Inertsil® ODS-3 with an isocratic elution using mobile phase consisting of acetonitrile, methanol, and water. Method validation has been carried out in accordance with the Commission Decision 2002/657/EC. Results The method was characterised by good recovery (82%) and precision (R.S.D 17 %). Decision limit (CCα) and detection capability (CCβ) was 0.05 μg L−1 and 0.09 μg L−1 respectively. The method met the criteria set out in Commission Decision 2002/657/EC for the purpose of confirmation in terms of retention time and ion ratio in the whole range of its application. Conclusions The developed method is specific and sensitive, suitable for measuring the natural level of testosterone in blood of cattle and for use in routine control programme for the detection of this hormone in bovine serum.
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Affiliation(s)
- Barbara Woźniak
- Department of Pharmacology and Toxicology National Veterinary Research Institute, 24-100 Pulawy, Poland
| | - Iwona Matraszek-Żuchowska
- Department of Pharmacology and Toxicology National Veterinary Research Institute, 24-100 Pulawy, Poland
| | - Sebastian Witek
- Department of Pharmacology and Toxicology National Veterinary Research Institute, 24-100 Pulawy, Poland
| | - Andrzej Posyniak
- Department of Pharmacology and Toxicology National Veterinary Research Institute, 24-100 Pulawy, Poland
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Thevis M, Kuuranne T, Walpurgis K, Geyer H, Schänzer W. Annual banned-substance review: analytical approaches in human sports drug testing. Drug Test Anal 2016; 8:7-29. [PMID: 26767774 DOI: 10.1002/dta.1928] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Revised: 11/10/2015] [Accepted: 11/10/2015] [Indexed: 12/30/2022]
Abstract
The aim of improving anti-doping efforts is predicated on several different pillars, including, amongst others, optimized analytical methods. These commonly result from exploiting most recent developments in analytical instrumentation as well as research data on elite athletes' physiology in general, and pharmacology, metabolism, elimination, and downstream effects of prohibited substances and methods of doping, in particular. The need for frequent and adequate adaptations of sports drug testing procedures has been incessant, largely due to the uninterrupted emergence of new chemical entities but also due to the apparent use of established or even obsolete drugs for reasons other than therapeutic means, such as assumed beneficial effects on endurance, strength, and regeneration capacities. Continuing the series of annual banned-substance reviews, literature concerning human sports drug testing published between October 2014 and September 2015 is summarized and reviewed in reference to the content of the 2015 Prohibited List as issued by the World Anti-Doping Agency (WADA), with particular emphasis on analytical approaches and their contribution to enhanced doping controls.
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Affiliation(s)
- Mario Thevis
- Center for Preventive Doping Research, Institute of Biochemistry, German Sport University Cologne, Am Sportpark Müngersdorf 6, 50933, Cologne, Germany.,European Monitoring Center for Emerging Doping Agents, Cologne/Bonn, Germany
| | - Tiia Kuuranne
- Doping Control Laboratory, United Medix Laboratories, Höyläämötie 14, 00380, Helsinki, Finland
| | - Katja Walpurgis
- Center for Preventive Doping Research, Institute of Biochemistry, German Sport University Cologne, Am Sportpark Müngersdorf 6, 50933, Cologne, Germany
| | - Hans Geyer
- Center for Preventive Doping Research, Institute of Biochemistry, German Sport University Cologne, Am Sportpark Müngersdorf 6, 50933, Cologne, Germany
| | - Wilhelm Schänzer
- Center for Preventive Doping Research, Institute of Biochemistry, German Sport University Cologne, Am Sportpark Müngersdorf 6, 50933, Cologne, Germany
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Munar A, Frazee C, Garg U. Quantification of Dehydroepiandrosterone, 11-Deoxycortisol, 17-Hydroxyprogesterone, and Testosterone by Liquid Chromatography-Tandem Mass Spectrometry (LC/MS/MS). Methods Mol Biol 2016; 1378:273-279. [PMID: 26602139 DOI: 10.1007/978-1-4939-3182-8_29] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Congenital adrenal hyperplasia (CAH) is a group of autosomal recessive disorders due to enzymatic defects in the biosynthetic pathway of cortisol and/or aldosterone. The analysis of cortisol, 17-hydroxyprogesterone (OHPG), dehydroepiandrosterone (DHEA), 11-deoxycortisol, and testosterone is generally performed in the diagnosis and/or follow-up of CAH. Cortisol is generally analyzed by immunoassays whereas other hormones are preferably assayed by liquid chromatography-tandem mass spectrometry (LC/MS/MS). A multiple reaction monitoring, positive mode atmospheric pressure chemical ionization, LC/MS/MS method is described for the simultaneous quantification of 17-hydroxyprogesterone, DHEA, 11-deoxycortisol, and testosterone. Stable-isotope labeled internal standards are added to serum samples and steroids are extracted by liquid-liquid extraction using methyl tert-butyl ether. The extract is evaporated under stream of nitrogen and the residue is reconstituted in methanol and analyzed by LC/MS/MS.
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Affiliation(s)
- Ada Munar
- Department of Pathology and Laboratory Medicine, Children's Mercy Hospitals and Clinics, 2401 Gillham Road, Kansas City, MO, 64108, USA
| | - Clint Frazee
- Department of Pathology and Laboratory Medicine, Children's Mercy Hospitals and Clinics, 2401 Gillham Road, Kansas City, MO, 64108, USA
| | - Uttam Garg
- Department of Pathology and Laboratory Medicine, Children's Mercy Hospitals and Clinics, 2401 Gillham Road, Kansas City, MO, 64108, USA.
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