{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,22]],"date-time":"2026-09-22T09:35:58Z","timestamp":1790069758001,"version":"4.0.1"},"reference-count":34,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2019,7,30]],"date-time":"2019-07-30T00:00:00Z","timestamp":1564444800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Lifepharm Centre for in vivo Pharmacology","award":["N\/A"],"award-info":[{"award-number":["N\/A"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Antioxidants"],"abstract":"<jats:p>Coenzyme Q10 (Q10) plays an important role in mammals for energy production in the mitochondria, and as a potent antioxidant. Oxidation ratio (% oxidized in relation to total Q10) has been proposed as an important biomarker. A sensitive and reproducible HPLC-ECD method was developed for determination of reduced and oxidized Q10 in canine plasma and heart tissue. Chromatographic separation was achieved in 10 min using a Waters Nova-pak C18 column and a mobile phase with lithium perchlorate in ethanol\/methanol\/2-propanol. The validation showed satisfying results. Excellent linear correlation was found (r2 &gt; 0.9997), intra- and inter-day precisions were below 6.5% (n = 5) and recoveries were between 89 and 109% (n = 5). Sensitivity stated as Lower Limit of Quantification (LLOQ) was 10 nM. Acceptable stability of both extracted and un-extracted samples was observed. The plasma concentration range of total Q10 was found to be between 0.64 and 1.24 \u00b5g\/mL. Comparison with a developed LC-MS\/MS method showed a correlation of r = 0.85 for reduced Q10 and r = 0.60 for oxidized Q10 (N = 17). However, average results were around 30% lower for ubiquinol using the LC-MS\/MS method as compared with the HPLC-ECD analysis. The two methods are therefore not considered to be interchangeable.<\/jats:p>","DOI":"10.3390\/antiox8080253","type":"journal-article","created":{"date-parts":[[2019,7,30]],"date-time":"2019-07-30T11:15:56Z","timestamp":1564485356000},"page":"253","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":16,"title":["Determination of Reduced and Oxidized Coenzyme Q10 in Canine Plasma and Heart Tissue by HPLC-ECD: Comparison with LC-MS\/MS Quantification"],"prefix":"10.3390","volume":"8","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-6375-8394","authenticated-orcid":false,"given":"Anne","family":"Schou-Pedersen","sequence":"first","affiliation":[{"name":"Section for Experimental Animal Models, Department of Veterinary and Animal Sciences, University of Copenhagen, Ridebanevej 9, 1870 Frederiksberg C, Denmark"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Dieter","family":"Schemeth","sequence":"additional","affiliation":[{"name":"Section for Environmental Chemistry and Physics, Department of Plant and Environmental Sciences, Thorvaldsensvej 40, 1870 Frederiksberg C, Denmark"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6514-8407","authenticated-orcid":false,"given":"Jens","family":"Lykkesfeldt","sequence":"additional","affiliation":[{"name":"Section for Experimental Animal Models, Department of Veterinary and Animal Sciences, University of Copenhagen, Ridebanevej 9, 1870 Frederiksberg C, Denmark"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2019,7,30]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"207","DOI":"10.1258\/000456303321610493","article-title":"Ubiquinone: cholesterol\u2019s reclusive cousin","volume":"40","author":"Hargreaves","year":"2003","journal-title":"Ann. Clin. Biochem."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"764","DOI":"10.1038\/sj.ejcn.1600880","article-title":"Coenzyme Q10 in health and disease","volume":"53","author":"Overvad","year":"1999","journal-title":"Eur. J. Clin. Nutr."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"119","DOI":"10.1016\/S0021-9150(96)06021-2","article-title":"Plasma ubiquinol-10 is decreased in patients with hyperlipidaemia","volume":"129","author":"Overvad","year":"1997","journal-title":"Atherosclerosis"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"74","DOI":"10.1016\/j.bbrc.2010.02.147","article-title":"Coenzyme Q-Biosynthesis and functions","volume":"396","author":"Bentinger","year":"2010","journal-title":"Biochem. Biophys. Res. Commun."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"367","DOI":"10.1016\/j.tcb.2015.12.007","article-title":"Understanding Ubiquinone","volume":"26","author":"Wang","year":"2016","journal-title":"Trends Cell. Biol."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"161","DOI":"10.1016\/j.jns.2004.05.007","article-title":"Redox status of plasma coenzyme Q10 indicates elevated systemic oxidative stress in Parkinson\u2019s disease","volume":"223","author":"Sohmiya","year":"2004","journal-title":"J. Neurol. Sci."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"230","DOI":"10.1016\/0003-9861(92)90511-T","article-title":"Distribution and redox state of ubiquinones in rat and human tissues","volume":"295","author":"Aberg","year":"1992","journal-title":"Arch. Biochem. Biophys."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"259","DOI":"10.1016\/j.pharmthera.2009.07.003","article-title":"Role of coenzyme Q10 (CoQ10) in cardiac disease, hypertension and Meniere-like syndrome","volume":"124","author":"Kumar","year":"2009","journal-title":"Pharmacol. Thera"},{"key":"ref_9","first-page":"1435","article-title":"Coenzyme Q10 for heart failure","volume":"52","author":"Madmani","year":"2014","journal-title":"Cochrane Database Syst. Rev."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"641","DOI":"10.1016\/j.jchf.2014.06.008","article-title":"The effect of coenzyme Q10 on morbidity and mortality in chronic heart failure: Results from Q-SYMBIO: A randomized double-blind trial","volume":"2","author":"Mortensen","year":"2014","journal-title":"JACC Heart Fail."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"285","DOI":"10.1016\/S0891-5849(00)00307-5","article-title":"Regulation of ubiquinone metabolism","volume":"29","author":"Dallner","year":"2000","journal-title":"Free Radic. Biol. Med."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"1610","DOI":"10.1016\/j.freeradbiomed.2010.03.002","article-title":"Coenzyme Q10 in human blood: Native levels and determinants of oxidation during processing and storage","volume":"48","author":"Franke","year":"2010","journal-title":"Free Radic. Biol. Med."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"256","DOI":"10.1093\/clinchem\/47.2.256","article-title":"HPLC analysis of reduced and oxidized coenzyme Q(10) in human plasma","volume":"47","author":"Tang","year":"2001","journal-title":"Clin. Chem."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"1038","DOI":"10.1002\/bmc.1567","article-title":"Validated HPLC method for the quantitative determination of CoQ(10) in dog plasma and its application to a pharmacokinetic study","volume":"25","author":"Yuan","year":"2011","journal-title":"Biomed. Chromatogr."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"341","DOI":"10.1016\/S0076-6879(99)99034-1","article-title":"High-performance liquid chromatography-coulometric electrochemical detection of ubiquinol 10, ubiquinone 10, carotenoids, and tocopherols in neonatal plasma","volume":"299","author":"Finckh","year":"1999","journal-title":"Methods Enzymol."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"106","DOI":"10.1016\/0003-2697(86)90203-4","article-title":"Simultaneous determination of tocopherols, ubiquinols, and ubiquinones in blood, plasma, tissue homogenates, and subcellular fractions","volume":"157","author":"Lang","year":"1986","journal-title":"Anal. Biochem."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"209","DOI":"10.1006\/abio.2000.4579","article-title":"Simultaneous detection of ubiquinol-10, ubiquinone-10, and tocopherols in human plasma microsamples and macrosamples as a marker of oxidative damage in neonates and infants","volume":"282","author":"Menke","year":"2000","journal-title":"Anal. Biochem."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"240","DOI":"10.3164\/jcbn.15-73","article-title":"Coenzyme Q10 serum concentration and redox status in European adults: Influence of age, sex, and lipoprotein concentration","volume":"58","author":"Niklowitz","year":"2016","journal-title":"J. Clin. Biochem. Nutr."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"265","DOI":"10.1177\/0004563215593097","article-title":"Rapid and sensitive analysis of reduced and oxidized coenzyme Q10 in human plasma by ultra performance liquid chromatography-tandem mass spectrometry and application to studies in healthy human subjects","volume":"53","author":"Claessens","year":"2016","journal-title":"Ann. Clin. Biochem."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"45","DOI":"10.1039\/B308690A","article-title":"Sensitive and selective analysis of coenzyme Q10 in human serum by negative APCI LC-MS","volume":"129","author":"Hansen","year":"2004","journal-title":"Analyst"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"68","DOI":"10.1016\/j.aca.2018.01.066","article-title":"Highly sensitive and selective determination of redox states of coenzymes Q9 and Q10 in mice tissues: Application of orbitrap mass spectrometry","volume":"1011","author":"Pandey","year":"2018","journal-title":"Anal. Chim. Acta"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"5600","DOI":"10.1039\/C4AN00760C","article-title":"Rapid assessment of the coenzyme Q10 redox state using ultrahigh performance liquid chromatography tandem mass spectrometry","volume":"139","author":"Tang","year":"2014","journal-title":"Analyst"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"88","DOI":"10.1016\/j.ab.2013.02.015","article-title":"Determination of coenzyme Q10 tissue status via high-performance liquid chromatography with electrochemical detection in swine tissues (Sus scrofa domestica)","volume":"437","author":"Niklowitz","year":"2013","journal-title":"Anal. Biochem."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"173","DOI":"10.1016\/j.cccn.2003.12.002","article-title":"Measurement of reduced and oxidized coenzyme Q9 and coenzyme Q10 levels in mouse tissues by HPLC with coulometric detection","volume":"341","author":"Tang","year":"2004","journal-title":"Clin. Chim. Acta"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"1165","DOI":"10.1016\/S0006-291X(84)80255-7","article-title":"Micro-analysis for coenzyme Q10 in endomyocardial biopsies of cardiac patients and data on bovine and canine hearts","volume":"123","author":"Vadhanavikit","year":"1984","journal-title":"Biochem. Biophys. Res. Commun."},{"key":"ref_26","unstructured":"(2019, July 29). Guidance for Industry. Bioanalytical Method Validation, Available online: https:\/\/www.fda.gov\/media\/70858\/download."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"63","DOI":"10.1111\/jvim.13663","article-title":"Breeding Restrictions Decrease the Prevalence of Myxomatous Mitral Valve Disease in Cavalier King Charles Spaniels over an 8- to 10-Year Period","volume":"30","author":"Birkegard","year":"2016","journal-title":"J. Vet. Intern. Med."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"893","DOI":"10.1016\/S0022-2275(20)37587-8","article-title":"Simultaneous determination of tissue tocopherols, tocotrienols, ubiquinols, and ubiquinones","volume":"37","author":"Podda","year":"1996","journal-title":"J. Lipid Res."},{"key":"ref_29","doi-asserted-by":"crossref","unstructured":"Littarru, G.P., Mosca, F., Fattorini, D., Bompadre, S., and Battino, M. (2004). Assay of Coenzyme Q10 in Plasma by a Single Dilution Step. Methods Enzymol, Academic Press.","DOI":"10.1016\/S0076-6879(04)78014-3"},{"key":"ref_30","unstructured":"Armstrong, D. (2008). Determination of Oxidized and Reduced CoQ10 and CoQ9 in Human Plasma\/Serum Using HPLC-ECD. Advanced Protocols in Oxidative Stress I, Humana Press."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"447","DOI":"10.2460\/ajvr.78.4.447","article-title":"Plasma coenzyme Q10 concentration, antioxidant status, and serum N-terminal pro-brain natriuretic peptide concentration in dogs with various cardiovascular diseases and the effect of cardiac treatment on measured variables","volume":"78","author":"Svete","year":"2017","journal-title":"Am. J. Vet. Res."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"58","DOI":"10.1177\/1091581811425256","article-title":"Oral repeated-dose toxicity studies of coenzyme Q10 in beagle dogs","volume":"31","author":"Beal","year":"2012","journal-title":"Int. J. Toxicol."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"892","DOI":"10.1016\/j.mad.2005.03.010","article-title":"Age-dependent change in Vitamin C status: A phenomenon of maturation rather than of ageing","volume":"126","author":"Lykkesfeldt","year":"2005","journal-title":"Mech. Aging Dev."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"1516","DOI":"10.1002\/rcm.1290091511","article-title":"Effects of solvent composition on molecular ion response in electrospray mass spectrometry: Investigation of the ionization processes","volume":"9","author":"Zhou","year":"1995","journal-title":"Rapid Commun. Mass Spectrom."}],"container-title":["Antioxidants"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2076-3921\/8\/8\/253\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T13:11:11Z","timestamp":1760188271000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2076-3921\/8\/8\/253"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2019,7,30]]},"references-count":34,"journal-issue":{"issue":"8","published-online":{"date-parts":[[2019,8]]}},"alternative-id":["antiox8080253"],"URL":"https:\/\/doi.org\/10.3390\/antiox8080253","relation":{},"ISSN":["2076-3921"],"issn-type":[{"value":"2076-3921","type":"electronic"}],"subject":[],"published":{"date-parts":[[2019,7,30]]}}}