HPLC purity comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Last reviewed on 2026-06-05. Where a claim depends on a specific study, the study is described rather than over-claimed.
Documentation accompanying research peptides usually includes a certificate of analysis listing the batch number, purity figure, and test methods applied. Buyers comparing suppliers should check whether the reported purity refers to chromatographic area or to a mass-balance calculation, because the two are not equivalent. Counter-ion content, residual solvents, and water content are sometimes omitted from such certificates even though they affect the actual peptide mass present. Independent verification through a second laboratory is the most direct way to confirm that a supplied material matches its label.
Purity assessment of peptide reagents normally relies on reversed-phase high-performance liquid chromatography. A gradient of acetonitrile in water with trifluoroacetic acid, paired with a C18 stationary phase, separates the target tetrapeptide from truncated sequences and deletion analogues. Detection at 214 nanometres exploits absorbance of the peptide backbone, since the molecule contains no aromatic residue. Results are expressed as a percentage of total peak area. Values above ninety-five percent are typical for research-grade material, although reporting conventions vary between suppliers.
Identity confirmation uses mass spectrometry, usually electrospray ionisation in positive mode or matrix-assisted laser desorption. The protonated free peptide produces a signal near three hundred and ninety-one daltons, while salt adducts shift that value slightly. Tandem mass spectrometry or amino acid analysis supplies sequence-level confirmation, which a single mass measurement cannot. Peptides containing aspartate can cyclise into succinimide intermediates that hydrolyse to isoaspartate isomers of identical mass. Because those isomers are difficult to separate chromatographically, identity and purity results carry more weight when interpreted together.
The parent extract epithalamin was characterised as a low-molecular-weight fraction of pineal tissue rather than a single defined chemical entity. Researchers fractionated it and tested successive fragments for activity, a screening approach typical of peptide discovery work in that era. Epitalon emerged from that process as one of the shorter sequences of interest. Because the original extract was never fully resolved into individual components, claims about which constituent drives a given effect rest on inference. This distinction matters when reading older reports that attribute extract observations to the tetrapeptide itself.
Epitalon is a synthetic tetrapeptide with the residue sequence alanine-glutamate-aspartate-glycine, commonly abbreviated AEDG. Its monoisotopic mass is approximately 390.35 daltons, and it is usually supplied as a lyophilised trifluoroacetate or acetate salt. The compound was derived from a pineal gland extract called epithalamin, a heterogeneous preparation investigated in the former Soviet Union. Researchers associated with the Saint Petersburg Institute of Bioregulation and Gerontology described the tetrapeptide as a constituent fragment of that extract. Commercial material is offered as a laboratory reagent rather than as a finished pharmaceutical product.
Literature searches for this compound must account for several spelling variants. Indexing databases contain epitalon, epithalon, epithalone, and AEDG, and relevant records are scattered across Russian-language and English-language journals that do not consistently cross-cite. Early publications describe the parent extract as a mixture of many peptides, whereas later work addresses the single synthetic tetrapeptide. That shift in nomenclature complicates comparison between studies, because extract data and tetrapeptide data are sometimes cited interchangeably. A search strategy omitting the alternate spellings will return an incomplete set of references.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Freeze-dried solid |
| Solubility class | Freely soluble in water | Aqueous buffers also suitable |
| Typical storage temperature | Minus 20 degrees Celsius or colder | Desiccated and light protected |
| Typical analytical method | RP-HPLC with UV detection | 214 nm on C18 column |
| Identity confirmation | Electrospray mass spectrometry | Sequence verified separately |
No pharmacopoeial monograph exists for this peptide, so quality rests on the supplier's internal specifications and on whatever independent testing a purchaser arranges. Certificates of analysis differ widely in which tests they report and in the limits applied. The counter-ion introduced during purification, commonly acetate or trifluoroacetate, changes the net peptide content of a given mass of powder, so two samples of equal weight may not contain equal amounts of the active sequence. Third-party laboratories can verify purity, identity, residual solvents, and counter-ion content for a fee, which makes documentation more informative than labelling.
Verification of a sample usually begins with reversed-phase high-performance liquid chromatography, which resolves the peptide from truncated sequences and other impurities and expresses purity as a percentage of total peak area. Mass spectrometry by electrospray ionisation or matrix-assisted laser desorption supplies an independent check, because the measured mass can be compared against the theoretical value for AEDG. Amino acid analysis or tandem mass spectrometry sequencing can confirm residue order. Each of these methods answers a different question: a purity figure does not establish identity, and an identity match does not establish how much of the material is intact peptide.
The molecule is a short, linear, hydrophilic peptide that dissolves readily in water or aqueous buffer. Its principal chemical liabilities are hydrolytic rather than oxidative, since it contains no cysteine, methionine, or tryptophan residues. The aspartate–glycine step is a recognised site for aspartimide formation under mildly acidic or basic conditions, generating isoaspartate and succinimide-related products over time. Desiccated lyophilised powder held at −20 °C is comparatively stable, whereas dilute solutions degrade faster and are best frozen as single-use aliquots rather than thawed repeatedly.
Published work on this compound consists mainly of in vitro experiments, animal studies, and small clinical investigations, a substantial share of which appeared in Russian-language journals. Sample sizes are generally small, control conditions differ between studies, and several endpoints rely on markers whose clinical meaning is itself debated. Reviews of the longevity field treat the peptide as an early example of telomerase-directed research rather than an established intervention. Regulatory treatment varies by country: some jurisdictions place it under prescription controls, others treat it as a laboratory material, and importation may be restricted regardless of local status.
Epitalon is a synthetic tetrapeptide whose sequence is alanine–glutamate–aspartate–glycine, commonly abbreviated AEDG. It was developed in Russia during the 1980s and 1990s by investigators associated with the St. Petersburg Institute of Bioregulation and Gerontology, who studied short peptides as regulators of gene expression and tissue function. The alternative spelling epithalon appears interchangeably in the literature, and the two names refer to the same molecule. Outside Russia it is encountered chiefly as a research chemical rather than a licensed medicine, and it holds no approval from the United States Food and Drug Administration or the European Medicines Agency.
The peptide is a synthetic analogue of epithalamin, a preparation extracted from bovine pineal glands. Investigators sought a short, chemically defined molecule that would reproduce some of the endocrine and gerontological observations attributed to the glandular extract. Proposed mechanisms centre on induction of telomerase activity, an effect reported in cultured human somatic cells in the early 2000s, together with influences on melatonin secretion and neuroendocrine regulation. Those mechanisms remain incompletely characterised, and the reported telomerase response has not been consistently reproduced by independent groups working in comparable systems.
Human data are limited to small studies, often without the randomization, blinding, or control groups expected in contemporary clinical research. Reported outcomes have included changes in melatonin levels, immune markers, and subjective measures, but sample sizes were generally too small to support firm conclusions. Some reviews treat the peptide as promising while noting methodological weaknesses; others question whether the observed effects are specific. The compound is frequently discussed in longevity-focused communities, where enthusiasm often outpaces the published evidence. Separating established findings from speculation is therefore important when reading summaries of this research.
Epitalon emerged from research conducted in Saint Petersburg by Vladimir Khavinson and colleagues, who studied short peptides as potential regulators of aging. The work built on epithalamin, a pineal gland extract reported to influence neuroendocrine function. Epitalon was designed as a synthetic counterpart with a defined sequence, allowing reproducible experiments that extracts could not support. Early publications described effects on melatonin rhythms and lifespan in animal models. These findings circulated mainly in Russian-language journals during the 1990s, which limited their visibility among English-speaking researchers.
The most widely cited claim is that epitalon activates telomerase and thereby extends telomere length. Supporting evidence comes largely from cultured human cells, where treatment was associated with increased telomerase activity and delayed replicative senescence. Telomerase activation is a biologically consequential effect, since the enzyme is largely silenced in most somatic cells. However, the route by which a short peptide would reach and act on the enzyme's regulatory machinery has not been established. Independent replication in human trials is scarce, so the link between cell-culture observations and whole-body aging remains an open question.
Storage recommendations center on limiting moisture, heat, and light. The dry powder is generally kept at minus 20 degrees Celsius, and some suppliers recommend minus 80 degrees for long-term archival. Once dissolved, solutions are usually aliquoted and frozen to avoid repeated freeze-thaw cycles, which can promote aggregation or degradation. Aqueous stability depends on pH and concentration, and buffered saline is often preferred over plain water for biological work. Stability data specific to epitalon remain limited, so general peptide-handling practices are applied by analogy rather than from product-specific validation.
Epitalon is a synthetic tetrapeptide with the sequence alanine-glutamate-aspartate-glycine, abbreviated AEDG. Its molecular formula is C14H22N4O9 and its calculated monoisotopic mass is approximately 390.35 daltons. The compound does not occur naturally as a free peptide; it is produced by solid-phase peptide synthesis. Because it contains two acidic residues and no basic residues, the neutral form carries a net negative charge at physiological pH. This charge profile influences how the peptide behaves in solution and during chromatographic analysis.
Laboratory-grade epitalon is typically supplied as a lyophilized powder. Purity is commonly assessed with reverse-phase high-performance liquid chromatography, often paired with mass spectrometry to confirm molecular identity. Amino acid analysis and peptide mapping can provide additional confirmation of sequence. Certificates of analysis for research materials frequently report purity above 95 percent, although the methods behind such figures vary between suppliers. The absence of a pharmacopeial monograph means that no single standardized assay defines the compound, so reported results depend on the analytical protocol chosen.
== Public reception == The discovery of Lindow Man in 1984 at Lindow Moss in Cheshire, England, received worldwide news coverage. Newspapers adopted the nickname "Pete Marsh", while scientists investigating his remains called him Lindow Man. In April 1985, a documentary about the investigation in the BBC television series Q.E.D. was watched by more than 10 million people. His first temporary exhibition at Manchester Museum in 1987 attracted up to 2,000 visitors a day. During the exhibition, local resident Barbara O'Brien led a campaign for his remains to stay permanently in North West England. The campaign gained support from local members of Parliament and attracted coverage in local and national newspapers. In November 1987, pupils at Lindow Primary School recorded O'Brien's song, "Lindow Man We Want You Back Again". The campaign was unsuccessful, and the British Museum retained the remains. The Manchester Museum exhibition of 2008–2009 presented different perspectives on Lindow Man through personal accounts from people involved in his discovery and study, museum curators, a local resident and a pagan contributor. According to museum curator Bryan Sitch, public responses were mixed but broadly favourable. Some visitors questioned the inclusion of a pagan viewpoint alongside scientific interpretations, while others criticised the design or wanted more factual information. Visitors left thousands of comment cards and personal offerings, which the museum collected for further study. The exhibition also contributed to debate about whether human remains should be displayed.
Researchers with the biotechnology company Rejuvenate Bio managed to extend the lifespans of elderly mice by 109%, reverse age-related frailty in the mice, and achieve signs of age reversal in human skin cells with gene therapy, employing partial cellular reprogramming.
Hong Kong has twelve universities. The University of Hong Kong (HKU), ranked QS Asia #1, was founded as the city's first institute of higher education in 1911 during the early colonial period. The Chinese University of Hong Kong (CUHK) was established in 1963 to fill the need for a university that taught using Chinese as its primary language of instruction. Along with the Hong Kong University of Science and Technology (HKUST) established in 1991, these universities are consistently ranked among the top 20 or top 50 universities worldwide. The Hong Kong Polytechnic University (PolyU) and City University of Hong Kong (CityU), both granted university status in 1994, are consistently ranked among the top 50 or top 100 universities worldwide. The Hong Kong Baptist University (HKBU) was granted university status in 1994 and is a liberal arts institution. Hong Kong Metropolitan University (formerly as Open University of Hong Kong before 2021) (attaining status in 1997), Lingnan University (in 1999), Hong Kong Shue Yan University (in 2006), Education University of Hong Kong (in 2016), Hang Seng University of Hong Kong (in 2018) and Saint Francis University (in 2024) all attained full university status in subsequent years.
Nondeletion forms: These defects, in general, involve a single base-pair substitution or small insertions near or upstream of the HBB gene. Deletion forms: base-pair deletions of different sizes involving the HBB gene produce syndromes such as hereditary persistence of fetal hemoglobin syndrome. Mutations are characterized as (βo) if they prevent any formation of β globin chains, and mutations are characterized as (β+) if they allow some β globin chain formation to occur.
The 1980s saw several new technologies that promised to change the way creatinine testing was done. Enzymatic and ion-exchange methods provided better accuracy but had other drawbacks. Enzymatic methods reduced some interferences but other new ones were discovered. High-performance liquid chromatography, HPLC, was more sensitive and specific, and had become the new reference method endorsed by the American Association for Clinical Chemistry. HPLC addressed the shortcomings of Jaffe-based methods, but was labor-intensive, expensive, and therefore impractical for routine analysis of the most frequently ordered renal analyte in medical labs. Simple, easily automated and cost-effective, Jaffe-based methods have persisted into the 21st century, despite their imperfections. By 2006, isotope dilution mass spectrometry (IDMS) became the reference method. To improve the accuracy in creatinine testing, new standards were developed by the National Institute of Standards and Technology (NIST). The College of American Pathologists (CAP) and the National Kidney Disease Education Program (NKDEP) collaborated with NIST to develop a new control reference called standard reference material 967 (SRM 967). SRM 967 aims to standardize calibration of creatinine testing, including Jaffe methods. Use of both IDMS and SRM 967 are currently recommended by the National Institutes of Health.
Sources: en.wikipedia.org
== External links == "Discrimination des femmes à l'embauche" [Discrimination against women in hiring] (in French). Archived from the original on March 28, 2007. "Hommes et femmes" [Men and women]. Observatoire des Inégalités (in French). Archived from the original on February 19, 2007. "Lutte contre les discriminations et promotion de l'égalité" [Fighting discrimination and promoting equality]. Defenseurs des droits (in French). Archived from the original on June 13, 2017. "La discrimination des femmes : un sujet d'actualité" [Discrimination against women: a topical issue]. CentrOjeunes (in French). December 6, 2012. Archived from the original on August 8, 2016. "Discrimination des femmes à l'embauche" [Discrimination against women in hiring] (in French). Archived from the original on March 28, 2007. "Haut conseil à l'égalité des droits" [High Council for Equal Rights]. Haut Conseil a L'égalité entre les femmes et les hommes (in French). Archived from the original on May 22, 2013. "Secrétariat d'état chargé de l'égalité entre femmes et hommes et de la lutte contre les discriminations" [State Secretariat for Gender Equality and Anti-Discrimination]. Haut Conseil a L'égalité entre les femmes et les hommes (in French). Archived from the original on January 7, 2013. "Maison de la justice et du droit" [House of Justice and Law] (in French). Archived from the original on April 12, 2013. "Association européenne contre les Violences faites aux Femmes au Travail" [European Association Against Violence Against Women at Work] (in French).
In addition, several Otago mayors including Mayor of Dunedin Sophie Barker, Mayor of Queenstown-Lakes John Glover, Mayor of Clutha Jock Martin, Mayor of Waitaki Mel Tavendale and Mayor of Central Otago Tamah Alley issued a joint statement that their councils were discussing merger options. Environment Southland chair Jeremy McPhail expressed disappointment that regional councils had been excluded from making proposals on the amalgamation process but said they would continue advocating.
=== Philanthropy === Morea serves as the captain and midfielder of the All Stars Football Club, a celebrity football team that participates in matches to raise funds for charitable causes. He played in a high-profile charity cricket match organized by the IIFA Foundation at Headingley Carnegie Stadium in Leeds, England, on 8 June 2007. The event featured a star-studded Indian celebrity team—including Virat Kohli, Kapil Dev, Vivek Oberoi, Ajay Devgn, Shilpa Shetty, Sunny Deol, and many others—competing against a UK celebrity team and the match benefited the IIFA Foundation's charitable causes. Morea attended a charity football match for the Salman Khan's Being Human Foundation in Mumbai on 15 August 2009. Dino joined Salman Khan, Aamir Khan, Amitabh Bachchan, and others for a blood donation camp in Bandra, Mumbai on 15 August 2010. In March 2013, he participated in a match to support the Magic Funds Organisation, which works with underprivileged children. In 2016, he became associated with Pet Fed, an event platform for pets, joining as an investor and supporter.
These 35 are known as primordial radionuclides. Well-known examples are uranium and thorium, but also included are naturally occurring long-lived radioisotopes, such as potassium-40. Each of the heavy primordial radionuclides participates in one of the four decay chains.
== Identification of ethylene oxide == Gas chromatography is the principal method for analysis and detection of ethylene oxide. An inexpensive test for ethylene oxide exploits its precipitation of solid hydroxides of metals when it is passed through aqueous solutions of their salts:
Sources: en.wikipedia.org
Reversed-phase high-performance liquid chromatography with ultraviolet detection at 214 nanometres is the usual approach. Peak area percentage provides a purity figure relative to other components in the sample. Mass spectrometry is then applied to confirm identity.
Aspartate can cyclise into a succinimide intermediate that later hydrolyses back as isoaspartate. Both forms share the same molecular mass, so mass spectrometry alone cannot tell them apart. This shapes how purity data should be interpreted.
Freeze-dried material is normally kept desiccated below minus twenty degrees Celsius and shielded from light. Solutions are prepared shortly before use and held cold. Repeated thawing is avoided because it accelerates aggregation and degradation.
It is based on epithalamin, a peptide-rich preparation obtained from pineal gland tissue and studied in the former Soviet Union. Researchers later identified the tetrapeptide AEDG as a constituent fragment of that material. Modern supplies are produced by chemical synthesis rather than tissue extraction.