LC-MS/MS is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Updated 2026-07-19. Numbers and descriptions here follow the published literature rather than marketing material.
Handling and quality assessment of cardarine reference material follow general laboratory practices for poorly characterized compounds. It typically appears as a white to off-white powder and is sparingly soluble in water but soluble in organic solvents such as dimethyl sulfoxide and ethanol. Storage recommendations usually specify a cool, dry, dark place, with long-term storage at low temperature and desiccation. Purity may be checked by high-performance liquid chromatography with ultraviolet detection, while identity is confirmed by mass spectrometry and nuclear magnetic resonance. No pharmacopeial monograph exists, so reported purity and stability depend on the supplier’s methods.
GW501516 acts as a selective agonist at PPARδ, a nuclear receptor that regulates transcription of genes involved in lipid handling and energy metabolism. Activation of PPARδ in preclinical models increases fatty acid oxidation, mitochondrial biogenesis, and exercise endurance in rodents. These effects have made the compound a subject of metabolic research and also a target for sport anti-doping rules. In humans, however, controlled studies are limited, and whether similar endurance or metabolic changes occur at tolerated exposures remains an open question. The receptor’s broad tissue distribution also means downstream effects may vary by organ and condition.
Detection of GW501516 in biological samples generally relies on liquid chromatography coupled with tandem mass spectrometry. Urine is a common matrix in anti-doping analysis, while blood or plasma may be used in research settings. Sample preparation can involve enzymatic hydrolysis, protein precipitation, or solid-phase extraction before instrumental analysis. Because the compound undergoes metabolism, assays may target the parent molecule, one or more metabolites, or both. Detection windows are not fixed; they depend on factors such as dose, route, individual metabolism, and assay sensitivity. Reference standards are required for accurate identification and quantification.
Stability of GW501516 depends on form, temperature, light exposure, and moisture. Solid reference material is typically stored frozen or refrigerated in a desiccator and protected from light. Solutions in organic solvents such as dimethyl sulfoxide are often kept frozen in aliquots to reduce freeze-thaw cycling. Aqueous solubility is low, so aqueous stock solutions can be difficult to prepare without cosolvents. Degradation may appear as changes in chromatographic purity or mass spectral signal. Stability studies are needed to establish shelf life for any specific preparation.
Quality assessment for cardarine samples usually combines identity, purity, and impurity testing. Nuclear magnetic resonance spectroscopy and mass spectrometry can confirm molecular structure, while high-performance liquid chromatography estimates purity. Certificates of analysis from testing laboratories may list these results, but they do not establish safety or legality. In the absence of approved manufacturing, products sold online may contain the wrong compound, variable amounts, or unlisted contaminants. Independent verification is therefore central to analytical work and to interpreting any reported biological activity.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Visual description for typical solid reference material. |
| Solubility | Poorly soluble in water; soluble in DMSO | Solubility depends on solvent, purity, and form. |
| Storage | Cool, dry, protected from light | Long-term storage often uses low temperature and desiccant. |
| Common analytical method | LC-MS/MS | Used for detection and quantification in biological matrices. |
| Common synonyms | GW-501516; GW501516; endurobol | Naming varies among literature, vendors, and databases. |
Cardarine is frequently described as a fat-burning or endurance-enhancing supplement, but these claims exceed the available evidence. The compound is not a hormone, steroid, or selective androgen receptor modulator. Research articles discuss it as a tool compound for studying PPARδ biology, while anti-doping literature focuses on its abuse and detection. Quality of unapproved products is uncertain, and independent analyses have found impurities or incorrect labeling. Open questions include whether human cancer risk resembles that seen in rodents and how often non-athletes use the substance.
Cardarine has no approved therapeutic indication and is not marketed as a medicine. The World Anti-Doping Agency lists GW501516 as a prohibited substance at all times, covering both in-competition and out-of-competition periods. National laws vary: some countries treat it as an unapproved drug subject to import controls, while others have specific restrictions on sale for human consumption. It is often sold as a research chemical, a label that does not imply safety or legality. Enforcement actions have targeted online vendors and shipments.
Activation of PPARδ changes transcription of genes involved in fatty acid transport, mitochondrial function, and skeletal muscle fuel preference. In rodent studies, pharmacological PPARδ activation was associated with increased endurance and altered body composition. These findings generated interest in performance enhancement, but species differences and study designs limit direct extrapolation to humans. Small human trials were conducted in the 2000s and later discontinued. The extent to which cardarine produces similar metabolic or performance effects in people remains an open question.
The compound is typically described as a laboratory compound rather than a therapeutic product. Published reports have explored its role in lipid disorders, insulin sensitivity, and exercise metabolism, yet no major drug regulator has approved it for medical use. Commercial samples sold under the cardarine name may vary in purity and identity. Analytical confirmation is therefore necessary when the material is discussed in scientific or regulatory contexts. Its classification as a prohibited substance in sport further shapes how it is studied and reported.
The Thiambutenes are a family of opioid analgesic drugs developed at the British research laboratory of Burroughs-Wellcome in the late 1940s. The parent compound thiambutene has no analgesic effects, but several compounds from this group are analgesics with around the same potency as morphine. Notable compounds include dimethylthiambutene, diethylthiambutene, ethylmethylthiambutene, pyrrolidinylthiambutene and piperidylthiambutene. Of these, ethylmethylthiambutene is the most potent, with 1.3x the potency of morphine, pyrrolidinylthiambutene is the least potent at 0.7x, and the rest are all around the same potency as morphine. Diethylthiambutene has been the most widely used, mainly in veterinary medicine. All of these compounds produced anticholinergic and antihistamine side effects, except for two of the weaker compounds diallylthiambutene and morpholinylthiambutene. They also all have a chiral centre on the alpha carbon (where the R1 group is attached) and so have two stereoisomers, with the dextro isomer being the more potent in all cases, although both isomers are active. Three of these compounds are explicitly listed as illegal drugs under UN convention, diethylthiambutene, dimethylthiambutene and ethylmethylthiambutene, and so are illegal throughout the world, but the rest will only be illegal in countries such as the US, Australia and New Zealand that have laws equivalent to the Federal Analog Act.
=== Not marketed === ACT-335827 – selective OX1 antagonist Almorexant (ACT-078573) – dual OX1 and OX2 antagonist – half-life 13–19 hours – development of the drug was abandoned in January 2011 EMPA – selective OX2 antagonist Filorexant (MK-6096) – dual OX1 and OX2 antagonist – half-life 3–6 hours – development was discontinued in 2015 GSK-649868 (SB-649868) – dual OX1 and OX2 antagonist – was in development for potential use in sleep disorders JNJ-10397049 – selective OX2 antagonist RTIOX-276 – selective OX1 antagonist SB-334867 – first non-peptide selective OX1 antagonist – has been shown to produce sedative and anorectic effects in animals SB-408124 – selective OX1 antagonist TCS-OX2-29 – first non-peptide selective OX2 antagonist
Atoms and molecules of gas or liquid can be trapped on a solid surface in a process called adsorption. This is an exothermic process involving a release of heat, and heating the surface increases the probability that an atom will escape within a given time. At a given temperature
Jack Straw (born 3 August 1946), Christian, of Eastern European Jewish ancestry; served in Cabinet under Labour governments of Tony Blair and Gordon Brown as Home Secretary and Foreign Secretary; has written for The Guardian, Daily Mail, El País, The Independent, The Mirror UK, The Sun, The Telegraph, Financial Times, The Times, POLITICO, LSE Connect, Prospect Magazine, The New European and is author or co-author of the following books; The English Job: Understanding Iran and Why It Distrusts Britain (2019) ISBN 978-1785903991; Implementation of the Human Rights Act 1998: Minutes of Evidence, Wednesday 14 March 2001 (2001) ISBN 0-10-442701-9; Making Prisons Work: Prison Reform Trust Annual Lecture (1998) ISBN 0-946209-44-8; Future of Policing and Criminal Justice (Institute of Police & Criminological Studies Occasional Paper S.) (1996) ISBN 1-86137-087-3 and Policy and Ideology (1993) ISBN 0-9521163-0-8 John Strawson, author of Encountering Islamic law, Partitioning Palestine: Legal Fundamentalism in the Palestinian-Israeli Conflict and editor of Law after Ground Zero and Tracking the Postcolonial in Law; also law professor at the University of East London School of Law, teaching International law and Middle East Studies; specialises in law and postcolonialism, with particular reference to middle east, Islam and international law; previous posts include visiting positions at Birzeit University (Palestine) and the Institute of Social Studies (The Hague Netherlands); researches encounter between western and Islamic law; is Director of Law Postgraduate Programmes at University of East London, and Director of the Centre on Human Rights in Conflict; believes use of term apartheid to describe Israel or Israeli policies does not apply to Israel, and use of analogy is unhistorical, and unhelpful. Jamie Susskind (b. 1989); barrister and author of Oxford University Press books on Marxism, freedoms, democracy and technology; was appointed as a research fellow at Harvard's Berkman Klein Center for Internet and Society; practises law at Littleton Chambers; his book Future Politics: Living Together in a World Transformed by Tech, listed by London School of Economics as one of top ten books of 2019; book approaches issues of technological change in political arena from legal standpoint, speculating on various ways technology would change interactions between citizens and political process; was awarded Book of the Year by Evening Standard and Prospect Magazine, Book of the Day by The Guardian and received the 2019 Estoril Global Issues Distinguished Book Prize; his book, The Digital Republic: On Freedom and Democracy in the 21st Century concerns dangers, problems, and solutions to Big Tech. Richard Susskind OBE FRSE (born 28 March 1961); author, speaker, independent adviser to international professional firms and national governments; IT adviser to Lord Chief Justice of England and Wales, holds professorships at the University of Oxford, Gresham College and Strathclyde University, is a past chair of Advisory Panel on Public Sector Information, and is president of the Society for Computers and Law; has authored nine books and is regular columnist at The Times. Adam Sutcliffe; Professor of European History at King's College London, journalist writing on Jewish history and identity for Times Literary Supplement, author of What Are Jews For: History, Peoplehood, and Purpose (Princeton University Press, 2020), Judaism and Enlightenment; coeditor of Philosemitism in History, The Cambridge History of Judaism: The Early Modern World, and History, Memory and Public Life: The Past in the Present. William Sutcliffe, novelist; New Boy (1986), Are You Experienced? (1997), Whatever Makes You Happy (2008), and The Wall (2013), set in an Israeli colony David Sylvester (21 September 1924 – 19 June 2001), prolific author, art critic, journalist and curator; trustee of the Tate Gallery; influential in promoting modern artists Francis Bacon, Joan Miró, and Lucian Freud; father of modern artist Cecily Brown; credited with coining the term Kitchen sink realism originally to describe a strand of post-war British painting. Mitchell Symons, writer Henri Tajfel (born Hersz Mordche; 22 June 1919 – 3 May 1982) was a Polish Jewish social psychologist and author, best known for his books and pioneering work on the cognitive aspects of prejudice and social identity theory, as well as being one of the founders of the European Association of Experimental Social Psychology. He also worked for the United Nations International Refugee Organization. Adam Thirlwell, FRSL (born 22 August 1978) is a British novelist. His work has been translated into thirty languages. He has twice been named as one of Granta's Best of Young British Novelists. In 2015 he received the E.M. Forster Award from the American Academy of Arts and Letters. He is an advisory editor of The Paris Review. Barbara Trapido (born 1941 as Barbara Schuddeboom), is a British novelist born in South Africa with German, Danish and Dutch ancestry. Born in Cape Town and growing up in Durban she studied at the University of Natal gaining a BA in 1963 before emigrating to London. After many years teaching, she became a full-time writer in 1970. Michael Tugendhat (born 21 October 1944),; retired High Court judge; was High Court's senior media judge; author and editor of The Law of Privacy and the Media Oxford University Press; Commercial Fraud: Civil Liability, Human Rights, and Money Laundering Oxford University Press; Les droits du genre humain : la liberté en France et en Angleterre (1159–1793), [The rights of mankind : liberty in France and England (1159–1793)] (with Elizabeth de Montlaur Martin, 2021), ISBN 978-2-36517-110-6, Société de Législation comparée, Paris (awarded by the French Académie des sciences morales et politiques the Prix Édouard Bonnefous 2022); Liberty Intact: Human Rights in English Law (2016) Oxford University Press and Fighting for Freedom? (2017), ISBN 978-1-911128-49-6, Bright Blue (organisation) Jackie Walker (activist), anti Zionist playwright, pro-Palestinian, anti fascist author, of Sephardi Jewish and Jamaican origin. Arthur Waley (1889–1966); orientalist and sinologist of Ashkenazi ancestry; renowned for his translations of Chinese and Japanese poetry; awarded the CBE in 1952, the Queen's Gold Medal for Poetry; invested as a Companion of Honour in 1956. Natasha Walter (born 20 January 1967), feminist writer, novelist, human rights activist, founder of charity Women for Refugee Women; father was Nicolas Walter, an anarchist and secular humanist writer; of German Jewish ancestry; journalist forVogue magazine; Deputy Literary Editor of The Independent; columnist and feature writer for The Guardian; appear regularly on BBC2's Newsnight Review and Radio 4's Front Row; was judge on the Booker Prize and was a judge on the Women's Prize for Fiction (formerly the Orange Prize); was the founder in 2006 of the charity Women for Refugee Women, where she was the director until 2021. The charity supports women who seek asylum to tell their stories and challenges injustices they experience. She was recognized as one of the BBC's 100 women of 2013. Nicolas Walter (22 November 1934 – 7 March 2000) was a British anarchist and atheist writer, speaker and activist. He was a member of the Committee of 100 and Spies for Peace, and wrote on topics of anarchism and humanism. Fredric Warburg (27 November 1898 – 25 May 1981), author, publicist, publisher best known for association with George Orwell. Besides his own work as an author, he promoted and published Franz Kafka. Other notable publications included The Third Eye by Lobsang Rampa, Adolf Hitler's Mein Kampf and William Shirer's The Rise and Fall of the Third Reich. Ruby Wax (née Wachs; born 19 April 1953) is an American-British actress, author of popular self-help books, comedian, television personality, and popular mental health campaigner, of Austrian Jewish descent; appointed Chancellor of the University of Southampton; Wax also teaches business communication in the public and private sectors. Clients include Deutsche Bank, the UK Home Office and Skype. Eyal Weizman (born 1970) is a British Israeli architect and author of over twenty books and academic papers, mostly on the Israeli occupation of Palestinian land and the architecture of the wall around Gaza. He is the director of the research agency Forensic Architecture at Goldsmiths, University of London where he is Professor of Spatial and Visual Cultures and a founding director there of the Centre for Research Architecture at the department of Visual Cultures. In 2019 he was elected Fellow of the British Academy. Rosie Whitehouse, journalist and author. Wife of Tim Judah and mother of Ben Judah; of Iraqi Jewish ancestry. Her historical research and profiles of Holocaust Survivors have been published by The Observer, The Jewish Chronicle, BBC News and Tablet magazine. Meanwhile, her writing about British government policy toward victims after the Holocaust and contemporary British antisemitism has appeared in The Independent and Haaretz. Stephen Winsten, (1893–1991) was the name adopted by Samuel Weinstein, one of the 'Whitechapel Boys' group of young Jewish men and future writers in London's East End in the years before World War I (the others included Isaac Rosenberg, John Rodker and Joseph Leftwich). In the First World War he was a conscientious objector, and imprisoned in Bedford and Reading gaols. He is now known for his works about George Bernard Shaw, and his writing on the life of Henry Salt. Robert Winston, Baron Winston (born 15 July 1940), British professor, author, journalist, medical doctor, scientist, television presenter and Labour Party politician.He is a member of Labour Friends of Israel; father of Ben Winston, renowned for producing a number of the annual Brit Awards from 2011 to 2014 and more recently he was a co-producer of US Grammy Awards and Tony Awards. Ludwig Wittgenstein (26 April 1889 – 29 April 1951) was an Austrian-Jewish British philosopher who worked primarily in logic, the philosophy of mathematics, the philosophy of mind, and the philosophy of language. He is considered by some to be the greatest philosopher of the 20th century. Richard Wollheim (5 May 1923 − 4 November 2003), prolific author noted for work on mind and emotions related to visual arts, specifically, painting; served as president of the British Society of Aesthetics; was Grote Professor of Mind and Logic, professor at Columbia University and University of California at Berkeley and lecturer at Balliol College, Harvard University, the University of Minnesota, Graduate Center, CUNY, the University of California at Davis; gave Andrew M. Mellon lectures in Fine Arts, National Gallery of Art, Washington; his book Art and its Objects considered one of the twentieth century's most influential texts on philosophical aesthetics; known for philosophical treatments of depth psychology, especially Sigmund Freud's Jonathan Wolff (born 1959) author of seven Oxford University Press academic books and numerous monographs and journals, philosopher and scholar; Professor of Values and Public Policy at the Blavatnik School of Government at the University of Oxford; Governing Body Fellow at Wolfson College; previously at University College London (UCL), where he was Professor of Philosophy and Dean of the Faculty of Arts and Humanities; was secretary of the British Philosophical Association and has been Editor and honorary secretary of the Aristotelian Society; presented a four-part series about the UK's National Health Service (NHS) for the BBC's Radio 3; was member of the Nuffield Council on Bioethics; was elected Fellow of the British Academy in 2023. Leonard Woolf, writer and activist Bat Ye'or (born 1933), best known for creating and popularising Eurabia conspiracy theory in her writings about modern Europe. Tamar Yellin (b. 1963), author whose first novel, The Genizah at the House of Shepher, won Sami Rohr Prize for Jewish Literature; granddaughter of Yitzhak Yaakov Yellin (1885–1964), pioneer of Hebrew language press in Palestine; Jane Yolen (February 11, 1939) is an American writer of fantasy and part-time resident in the UK, science fiction, and children's books. She is the author or editor of more than 400 books, of which the best known is The Devil's Arithmetic, a Holocaust novella Israel Zangwill (1864–1926), novelist and playwright. Zangwill was a British author at the forefront of cultural Zionism during the 19th century, and was associate of Theodor Herzl, later rejecting search for a Jewish homeland in Palestine. Father of Oliver Zangwill and husband of Suffragette Edith Ayrton. Theodore Zeldin, writer
Sources: en.wikipedia.org
=== Broken specimens === Broken specimens are reattached to the herbaria sheet using thinly cut strips of archival pre-gummed linen tape. Detached materials such as seeds or leaves are placed in an acid-free card fragment packet, which is secured onto the sheet with the original specimen.
== Common uses == The chuck contains large amounts of connective tissue, including collagen, which partially melts during cooking. Meat from the chuck, once divided, is usually used for stewing, slow cooking, braising, or pot roasting and is ideal in a one-pot cooker. The top blade part of the chuck is preferred for grilling because it is the second tenderest steak once the gristle is removed. The fifth rib taken from the chuck can also be used as an alternative to the prime rib roast, which is usually from bones 6–12. They are similar in terms of the proportion of meat and bone, although the fifth rib exceeds the prime rib in the amount of lean meat. The cross-cut or cross rib, which is the last part of the chuck located between the brisket point and the short rib, can also be used as an alternative to the blade when cooking steaks. The chuck part cut from the shoulder clod is also used in place of sirloin since it has a very beefy taste.
Several major Big Boy franchisees accepted Marriott's offer and became Roy Rogers regional franchisees, including Abdow's, Frisch's, Elias Brothers, Marc's, and Shoney's which together covered much of the Northeastern, Midwest and Southern US. Pittsburgh franchisee Eat'n Park rejected the offer and took public offense at paying fees to Rogers. In the Pittsburgh area and elsewhere, other regional franchisees were sought who would also subfranchise to smaller operators, and by January 1969, Marriott claimed regional franchises for every state but Alaska. Roy Rogers' restaurants also opened in Canada, franchised to that nation's Big Boy franchisee, JB's of Canada. Marriott divided the United States into 33 franchise regions and required regional franchisees open a set number of restaurants in a four-year period. Regional franchisees would pay Marriott a 2% royalty, and subfranchisees typically pay the regional franchisee 3%, who would keep the additional 1%. A restaurant required a $35,000 cash investment upfront, including $7,500 paid to Marriott. Additionally, the cost of the building and equipment, with seating for 42 persons, cost about $100,000 in 1968, excluding the cost of land. Marriott offered financing but charged an interest rate of 12% on land and 17% for the building. The prototype restaurant seated 40 to 45 persons with additional outdoor seating on an optional patio in front of the building, but actual restaurants varied, one franchisee's dining area accommodating 75 persons.
== Structure == The structure is a disulfide rich alpha+beta fold. Bovine pancreatic trypsin inhibitor is an extensively studied model structure. Certain family members are similar to the tick anticoagulant peptide (TAP, P17726). This is a highly selective inhibitor of factor Xa in the blood coagulation pathways. TAP molecules are highly dipolar, and are arranged to form a twisted two-stranded antiparallel beta sheet followed by an alpha helix. The majority of the sequences having this domain belong to the MEROPS inhibitor family I2, clan IB; the Kunitz/bovine pancreatic trypsin inhibitor family, they inhibit proteases of the S1 family and are restricted to the metazoa with a single exception: Amsacta moorei entomopoxvirus, a species of poxvirus. They are short (about 50 to 60 amino acid residues) alpha/beta proteins with few secondary structures. The fold is constrained by three disulfide bonds. The type example for this family is BPTI (or basic protease inhibitor), but the family includes numerous other members, such as snake venom basic protease; mammalian inter-alpha-trypsin inhibitors; trypstatin, a rat mast cell inhibitor of trypsin; a domain found in an alternatively spliced form of Alzheimer's amyloid beta-protein; domains at the C-termini of the alpha-1 and alpha-3 chains of type VI and type VII collagens; tissue factor pathway inhibitor precursor; and Kunitz STI protease inhibitor contained in legume seeds.
== Prevalence == Over 30% of athletes participating in 2011 World Championships in Athletics admitted having used banned substances during their careers. According to a study commissioned by the World Anti-Doping Agency (WADA), actually 44% of them had used them. Nevertheless, only 0.5% of those tested were caught. The entire Russian track and field team was banned from the 2016 Olympic Games, as the Russian State had sponsored and essentially sanctioned their doping program.
Sources: en.wikipedia.org
hENT3 is expressed highly in the cerebral cortex, lateral ventricle, ovary and adrenal gland. hENT4 is more commonly known as the plasma membrane monoamine transporter (PMAT), as it facilitates the movement of organic cations and biogenic amines across the membrane.
At the start of 1944, Major General James Doolittle, the new commander of the 8th Air Force, released most fighters from the requirement of flying in close formation with the bombers, allowing them free rein to attack the Luftwaffe wherever it could be found. The aim was to achieve air supremacy. Mustang groups were sent far ahead of the bombers in a "fighter sweep" to intercept German fighters. Bomber crews complained, but by June, supremacy was achieved. The Luftwaffe's twin-engined Messerschmitt Bf 110 Zerstörer heavy fighters brought up to deal with the bombers proved to be easy prey for the Mustangs, and had to be quickly withdrawn from combat. The Focke-Wulf Fw 190A, already suffering from poor high-altitude performance, was outperformed by the Mustang at the B-17's altitude, and when laden with heavy bomber-hunting weapons and extra armor as a replacement for the more vulnerable twin-engined Zerstörer heavy fighters, these variants had poor manuverability and suffered heavy losses. The Messerschmitt Bf 109 had comparable performance to the P-51 at high altitudes, but its lightweight airframe was even more affected by increases in armament. The Luftwaffe answered with the Gefechtsverband ("battle formation"). This consisted of a Sturmgruppe of heavily armed and armored Fw 190As escorted by two Begleitgruppen of Bf 109s, whose task was to keep the Mustangs away from the Fw 190s as they attacked the bombers. This strategy proved to be problematic, as the large German formation took a long time to assemble and was difficult to maneuver.
=== Homologous recombination === Another method of cloning without the use of ligase is by DNA recombination, for example as used in the Gateway cloning system. The gene, once cloned into the cloning vector (called entry clone in this method), may be conveniently introduced into a variety of expression vectors by recombination.
{\displaystyle \mathrm {Purity} ={\frac {w_{\mathrm {std} }\times n[\mathrm {H} ]_{\mathrm {std} }\times MW_{\mathrm {spl} }}{w_{\mathrm {spl} }\times MW_{\mathrm {std} }\times n[\mathrm {H} ]_{\mathrm {spl} }}}\times P}
Sources: en.wikipedia.org
Cardarine targets PPARδ, a nuclear receptor involved in lipid and energy metabolism. It does not bind the androgen receptor in the way SARMs do.
Most methods use liquid chromatography with tandem mass spectrometry. Urine is common in anti-doping testing, and blood or plasma may be used in research.
Typical guidance is cool, dry, dark storage, often at low temperature and with desiccant. Stability data are limited, so storage conditions should be verified for each batch or supplier.
LC-MS/MS is common, often after sample cleanup. The assay targets GW501516 or its metabolites.