The short version of RP-HPLC fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2026-04-13. Anything still debated is marked as such rather than presented as settled.
Copper takes part in redox chemistry, and the same property that makes it useful in enzymes can generate reactive oxygen species when the ion is loosely bound. GHK chelates copper through imidazole, amino, and amide nitrogen donors, which reduces the amount of free copper in solution. Whether that chelation is protective, neutral, or harmful in a given tissue is not settled. Laboratory assays report both antioxidant and pro-oxidant behavior, depending on the conditions and the readout used.
Published work on GHK-Cu is dominated by in vitro experiments and small animal studies. Human trials tend to be short and small, with endpoints such as skin appearance rather than clinical outcomes. Review articles often summarize the same underlying laboratory findings, which can make the evidence base look broader than it is. Several basic questions remain open: the concentration of the intact complex in human tissue, the route by which it crosses the skin barrier, and whether effects seen in culture produce measurable changes in people.
Identity and purity are usually assessed with reversed-phase high-performance liquid chromatography, often paired with mass spectrometry. Copper content is measured separately by techniques such as inductively coupled plasma mass spectrometry or atomic absorption. Amino acid analysis confirms the peptide sequence after hydrolysis. Because the metal and the peptide can be quantified independently, a complete certificate of analysis normally reports both values rather than a single purity figure. This separation of measurements is important when comparing suppliers.
Solid GHK-Cu appears as a blue to blue-violet powder, and the colour is a direct consequence of copper coordination. The complex dissolves readily in water and in many polar solvents, while the free peptide behaves differently. Solubility in nonpolar media is low, which limits its use in oil-based systems. Solutions are typically prepared fresh because the dissolved form is more exposed to hydrolysis and to loss of the metal ion than the dry powder. Working concentrations are usually low, and preparation notes often specify the solvent and the order of addition.
Dry material is typically held at low temperature, often around minus twenty degrees Celsius, and protected from moisture and light. Copper complexes can release their metal ion under acidic conditions or in the presence of competing chelators. Hydrolysis of the peptide backbone is a slower but real pathway, and the histidine residue is susceptible to oxidation over long periods. Stability statements therefore depend on formulation, pH, and container, and they should be read as conditional rather than absolute.
| Property | Value | Notes |
|---|---|---|
| Copper binding sites | Imidazole, amino, and amide nitrogens | Form chelate rings with Cu(II) |
| Conditional binding constant | Reported near 10^16 at neutral pH | Value depends on method and medium |
| Visible absorption | Broad band in the blue-violet region | Source of the characteristic color |
| Common analytical methods | LC-MS, HPLC, UV-Vis, ICP-OES | Used for identity and copper content |
| Main degradation routes | Oxidation, photolysis, hydrolysis | Accelerated by light, heat, and pH extremes |
Identity and purity are assessed mainly by reversed-phase high-performance liquid chromatography with ultraviolet detection, often paired with mass spectrometry to confirm the expected mass. Copper content is measured separately by inductively coupled plasma optical emission spectrometry or atomic absorption spectroscopy, because the peptide assay alone does not establish the metal-to-peptide ratio. Visible spectroscopy provides a rapid check on complex integrity through the absorption band in the visible region. Agreement between the peptide assay and the copper assay is the practical test of whether a sample is the intended complex rather than a mixture.
Aqueous solutions of GHK-Cu are less stable than the dry powder. The peptide backbone is vulnerable to hydrolysis at extreme pH, and copper can be stripped from the complex by strong chelating agents such as EDTA or citrate. Oxidising agents and high concentrations of ascorbic acid can reduce copper(II) and change the complex, which is one reason formulators often keep such ingredients in separate phases. How quickly these changes occur under real storage conditions depends on pH, buffer, temperature and packaging, and quantitative data on the subject are limited.
Copper binds to the peptide through the histidine imidazole nitrogen and the terminal amino group, forming a stable square-planar complex. Binding constants reported for copper(II) with GHK are high, so the peptide competes effectively for copper in solution. The complex absorbs visible light, which gives solutions a blue to violet colour. Whether the metal-free peptide has a distinct biological function of its own is still an open question; some work treats it mainly as a copper delivery vehicle, while other work reports peptide-specific effects.
The compound was first isolated from human plasma in the 1970s by Loren Pickart, who later described copper-binding activity in liver and other tissues. Early reports focused on its presence in blood and its ability to carry copper between proteins. Commercial and cosmetic use of the term 'copper peptide' has since broadened, and labels rarely distinguish GHK-Cu from other copper-binding fragments. This naming overlap makes literature searching harder, because cosmetic ingredient lists, supplier catalogues and laboratory papers use different vocabularies for the same molecule.
GHK-Cu is the copper-binding complex formed by the tripeptide glycyl-L-histidyl-L-lysine and a copper(II) ion. The free peptide is usually written as GHK, and the complex is written as GHK-Cu or Cu-GHK. The sequence was identified in human plasma and later detected in saliva and urine. Its name comes from the single-letter codes of glycine, histidine and lysine. The complex is widely described as a naturally occurring carrier of copper in blood rather than as a free peptide with its own hormonal role.
=== Obesity and metabolic disorders === Microbial therapeutics are also being explored as treatments for obesity and metabolic diseases such as diabetes. Certain gut microorganisms influence how the body absorbs nutrients, stores energy, and regulates blood sugar. By changing the activity or composition of these microbes, it may be possible to improve metabolic health. In addition, genetically engineered bacterial and yeast have been developed to produce hormones that help regulate appetite and glucose levels. For example, some engineered microbes release substances similar to the hormone glucagon-like peptide-1 (GLP-1), which supports insulin release and promotes feelings of fullness. Because these microbes can live in the gut, they may provide longer-lasting effects than traditional medications.
By the mid-1990s, several GH companies had sponsored or publicized research into the quality of life of adults with severe GH deficiency. Most were people having been treated with GH in childhood for severe deficiency. Many of them stopped injections as they reached their final heights in the low-normal range. However, as adults in their 30s and 40s, these people, who had been children with growth hormone deficiency, were now adults with growth hormone deficiency and had more than their share of common adult problems: reduced physical, mental, and social energy, excess adipose and diminished muscle, diminished libido, poor bone density, higher cholesterol levels, and higher rates of cardiovascular disease. Research trials soon confirmed that a few months of GH could improve nearly all of these parameters. However, despite marketing efforts, most GH-deficient adults remain untreated. Though GH use was slow to be accepted among adults with GH deficiency, similar research to see if GH treatment could slow or reverse some of the similar effects of aging attracted much public interest. The most publicized trial was reported by Daniel Rudman in 1990. As with other types of hormone supplementation for aging (testosterone, estrogen, DHEA), confirmation of benefit and accurate understanding of risks has been only slowly evolving. In 1997, Ronald Klatz of the American Academy of Anti-Aging Medicine published Grow Young With HGH: The Amazing Medically Proven Plan To Reverse the Effects Of Aging, an uncritical touting of GH as the answer to aging.
A chart or table of nuclides maps the nuclear, or radioactive, behavior of nuclides, as it distinguishes the isotopes of an element. It contrasts with a periodic table, which only maps their chemical behavior, since isotopes (nuclides that are variants of the same element) do not differ chemically to any significant degree, with the exception of hydrogen. Nuclide charts organize nuclides along the X axis by their numbers of neutrons and along the Y axis by their numbers of protons, out to the limits of the neutron and proton drip lines. This representation was first published by Kurt Guggenheimer in 1934 and expanded by Giorgio Fea in 1935, Emilio Segrè in 1945 or Glenn Seaborg. In 1958, Walter Seelmann-Eggebert and Gerda Pfennig published the first edition of the Karlsruhe Nuclide Chart. Its 7th edition was made available in 2006. Today, there are several nuclide charts, four of which have a wide distribution: the Karlsruhe Nuclide Chart, the Strasbourg Universal Nuclide Chart, the Chart of the Nuclides from the Japan Atomic Energy Agency (JAEA), and the Nuclide Chart from Knolls Atomic Power Laboratory in the United States. It has become a basic tool of the nuclear community.
In 1969, Williams made a special effort to instruct Epstein on how to improve as a hitter, with a focus on teaching Epstein to only swing at strikes. That year, Epstein had career highs in batting average, home runs, bases on balls, runs batted in, runs scored, on-base percentage, and slugging percentage. In only 18 more at-bats in 1969 than 1968, he had 17 more home runs, 33 more runs and 52 more RBIs; and his batting average increased from .234 to .278. In 1970, however, Epstein's hitting declined as his average against left-handed pitching fell considerably. In May 1971, he was traded along with Darold Knowles to the Oakland Athletics for Frank Fernandez, Don Mincher, Paul Lindblad, and cash. In 1971, while hitting 18 home runs in 329 at bats, he was hit by a pitch 12 times, leading the league. In 1972 he hit 26 home runs (3rd in the league) for the world champion Athletics. He hit a home run every 17.5 at bats (3rd in the AL), had a .490 slugging percentage (5th), had a .376 on-base percentage (6th), collected 62 walks (10th), and was hit by a pitch 11 times (2nd). He was 16th in voting for the American League MVP. However, in late May, while on the road in Arlington Texas, Epstein and slugger Reggie Jackson came to blows in the clubhouse over Epstein's use of complimentary tickets for family members. The next day, owner Charlie Finley asked him about the incident. Finley claimed Epstein attacked his star player (Jackson). Epstein disputed that, claimed that Jackson was the problem, and demanded to be traded.
=== Collaborative history with Pharrell Williams === As a teenage rapper, Malice met music producers Chad Hugo and Pharrell Williams in 1988 and 1990, respectively. Hugo and Williams knew each other and would go on to form the production duo the Neptunes. One day, Pusha T was at Hugo's house and started rapping. Impressed, Williams convinced the brothers to form a rap duo. Clipse's intended debut album, Exclusive Audio Footage (1999), was shelved by Elektra Records; their actual debut Lord Willin' was released by the Neptunes' record label Star Trak Entertainment in 2002. The Neptunes would go on to have production credits on every commercially released studio album by Clipse until the latter's disbandment. Williams claimed to not be on speaking terms with Hugo in 2024 in light of a lawsuit from the latter against him over claims that he was monopolizing the Neptunes name. When asked in 2024 if Clipse worked with Hugo on Let God Sort Em Out, Pusha T denied it. He also responded not being "familiar with" the lawsuit. Clipse stated in 2025 that they still have a strong personal relationship with Hugo, although they differed on whether they missed working with him musically; Pusha T stated that his favorite Clipse album Hell Hath No Fury (2006) was produced entirely by Williams. Malice references the breakup on promotional single "So Be It"—"Ain't no more Neptunes, so P's Saturn."
Sources: en.wikipedia.org
Kelly Bailey is an American composer, musician, programmer and sound designer. He was the senior game designer of sound and music at Valve until he left in 2011 with Mike Dussault to concentrate on their project, Sunspark Labs LLC. Valve composer Mike Morasky mentioned in February 2014 that Bailey had returned to Valve, but in a February 2016 article on Forbes it was reported that Bailey has founded his own company, IndiMo Labs, and that he is no longer working at Valve.
== Chemical properties == Ethylene oxide readily reacts with diverse compounds with opening of the ring. Its typical reactions are with nucleophiles which proceed via the SN2 mechanism both in acidic (weak nucleophiles: water, alcohols) and alkaline media (strong nucleophiles: OH−, RO−, NH3, RNH2, RR'NH, etc.). The general reaction scheme is
Efraim Halevy (Hebrew: אפרים הלוי; born in London, 2 December 1934); Israeli intelligence expert and diplomat; was director of Mossad and 3rd head of Israeli National Security Council; author of Man in the Shadows, covering Middle Eastern history since the late 1980s; nephew of Sir Isaiah Berlin; has written for The Washington Post, Jerusalem Post, Times of Israel, Haaretz, Foreign Affairs, Ynet News, The Forward Simon Hattenstone (born 29 December 1962 in Salford, England) journalist and writer; features writer and interviewer for The Guardian. He has also written or ghost-written a number of biographical books. Paula Heimann; (2 February 1899 – 22 October 1982), author, academic, psychiatrist and psychoanalyst who established phenomenon of countertransference as important tool of psychoanalytic treatment, publishing influential studies, texts, academic papers and monographs; member of British Psychoanalytical Society; author of monograph A contribution to the problem of sublimation and paper On counter-transference, presented at the Psychoanalytical Congress in 1949 in Zurich, led to rift with Kleinian group of analysts; later turned to the Independents group and was Margarete Mitscherlich's analyst; Alexander Mitscherlich also underwent training analysis with her. Margot Heinemann (18 November 1913 – 10 June 1992) was a British Marxist writer, drama scholar, and leading member of the Communist Party of Great Britain (CPGB).
2018 results of the TIME trial, which used a randomized, double-blind, placebo-controlled trial design, concluded that "bone marrow mononuclear cells administration did not improve recovery of LV function over 2 years" in people who had a myocardial infarction. Accordingly, the BOOST-2 trial conducted in 10 medical centers in Germany and Norway reported that the trial result "does not support the use of nucleated BMCs in patients with STEMI and moderately reduced LVEF". Furthermore, the trial also did not meet any other secondary MRI endpoints, leading to a conclusion that intracoronary bone marrow stem cell therapy does not offer a functional or clinical benefit. In 2021, stem cell injections in the US have caused grave infections in at least 20 patients who received umbilical cord blood-derived products marketed as "stem cell treatment". In 2023, the case of a woman who was infected with Mycobacterium abscessus and sustained meningitis after stem cell treatment for multiple sclerosis at a commercial clinic in Baja California, Mexico was published.
NP-40 (also known as Tergitol-type NP-40 and nonyl phenoxypolyethoxylethanol) is a commercially available detergent with CAS Registry Number 9016-45-9. NP-40 is an ethoxylated nonylphenol for non-ionic surfactants and can act as emulsifier and demulsifier agent. NP-40 is often used to break open all membranes within a cell, including the nuclear membrane . To break only the cytoplasmic membrane, other detergents such as digitonin can be used. NP-40 has applications in paper and textile processing, in paints and coatings, and in agrochemical manufacturing. Care should be taken to avoid confusing NP-40 with Nonidet P-40 (octyl phenoxypolyethoxylethanol) which is currently out of production. Nonidet P-40 ("Non-Ionic Detergent") was originally manufactured and trademarked by the Shell Chemical Company, but was phased out of production in the early 2000s. Confusingly, biochemical protocols published between the 1960s and 2000s refer to Shell's Nonidet P-40 as NP-40. Shell's original Nonidet P-40 had a hydrophilic-lipophilic balance (HLB) value of 13.5, as opposed to 12.9 for the currently available IGEPAL CA-630, indicating that the currently available compound is more potent than the compound used in older publications. Indeed, according to a 2017 report, an additional dilution factor of 10 was required for the currently available NP-40 ("Nonidet P-40 substitutes") to match the activity of the previously available, and now discontinued, Shell's Nonidet P-40.
Sources: en.wikipedia.org
It is not approved as a pharmaceutical in major markets and is used mainly as a cosmetic ingredient and a laboratory reagent. Regulatory status varies by country and by the product category in which it appears. Claims about therapeutic effects should be treated separately from permitted cosmetic labeling.
Reversed-phase high-performance liquid chromatography and mass spectrometry are common for the peptide portion. Copper content is usually determined by inductively coupled plasma techniques or by spectrophotometry. Ultraviolet-visible spectroscopy takes advantage of the visible absorption band of the copper complex.
Light, oxygen, and elevated temperature promote degradation of the peptide, and strongly acidic or alkaline conditions accelerate hydrolysis. The copper complex is generally more resistant to oxidation than the free peptide. Storage in a dry, dark, cold environment limits loss over time.
The colour comes from electronic transitions in the coordinated copper(II) ion. Ligand field effects absorb part of the visible spectrum. A colourless or greenish sample may indicate degraded material.