This is a working overview of ICP-MS, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2025-10-21. Anything still debated is marked as such rather than presented as settled.
The sequence now called GHK was first reported in the early 1970s after isolation from human plasma, where it was noted to influence liver cell behavior in laboratory preparations. Later work described a copper-binding form and its activity in fibroblast and wound-model experiments. Review articles frequently group the substance with other copper peptides. Concentrations in blood appear to fall with age in several small surveys, although the reason for this trend is not settled. Whether such a decline carries functional consequences remains an open question.
Published work on GHK-Cu concentrates largely on cell culture systems rather than whole organisms. Frequently used endpoints include collagen synthesis, expression of matrix metalloproteinases, and migration of fibroblasts. Some reports describe antioxidant behavior, while others stress delivery of copper into cells. These mechanisms are proposed rather than demonstrated, and the relative weight of each pathway is unclear. Human trials are few and generally small, so laboratory findings should not be read as confirmed clinical results.
GHK-Cu is a coordination complex formed between the tripeptide glycyl-L-histidyl-L-lysine and a copper(II) ion. The peptide backbone consists of glycine, histidine, and lysine joined in that order. Copper is held through the imidazole nitrogen of histidine and the alpha-amino group at the N-terminus, which together produce a square-planar arrangement around the metal center. The solid appears blue to violet, a color that originates from d-d electronic transitions within the copper coordination sphere. The complex is indexed under CAS number 89030-95-5.
Purity assessment typically involves high-performance liquid chromatography for the peptide and atomic spectroscopy for copper content. The ratio of copper to peptide is a key quality parameter; a value near one indicates proper stoichiometry. Impurities can include free peptide, copper salts, and truncated sequences from synthesis. Because the complex is dynamic, sample preparation and mobile-phase conditions can shift the observed species. Reported purity values therefore depend on the analytical method and should be interpreted with that context.
Characterizing GHK-Cu requires methods that distinguish the intact complex from free peptide and unbound copper. UV-visible absorption around 600 nm provides a rapid check for copper coordination, while circular dichroism reports on peptide secondary structure. Mass spectrometry confirms the peptide mass and can detect copper adducts under carefully controlled conditions. Electron paramagnetic resonance is particularly informative for Cu(II) because it reveals the ligand field symmetry. No single technique fully defines the complex, so laboratories combine orthogonal methods.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Copper(II) peptide complex | Peptide chain coordinated to a single metal ion |
| CAS number | 89030-95-5 | Indexed for the peptide-copper complex |
| Molecular formula | C14H22CuN6O4 | Approximate formula for a one-to-one complex |
| Appearance | Blue to violet solid | Color from copper d-d transitions |
| Solubility class | Freely soluble in water | Also dispersible in some polar solvents |
Analytical verification commonly relies on high-performance liquid chromatography for purity assessment and mass spectrometry for identity confirmation. Spectroscopic methods such as UV-visible absorption and electron paramagnetic resonance can probe the metal centre itself, since the d9 configuration of copper(II) produces characteristic signals. Elemental analysis or plasma-based techniques quantify copper content. Because each method reports a different aspect of the same sample, purity figures are most meaningful when the technique and its detection wavelength are stated alongside the value.
Stability of the complex in solution depends on pH, temperature, and the presence of competing ligands. It is generally described as more resistant to breakdown than the metal-free chain, since coordination reduces susceptibility to enzymatic attack. Oxidation and hydrolysis can nevertheless proceed over time in aqueous media. Storage guidance in laboratory settings commonly involves refrigeration, protection from light, and avoidance of strongly alkaline conditions. Published data on long-term behaviour vary considerably and depend on the specific matrix.
Material described as GHK-Cu appears in several distinct markets, including cosmetic ingredients, laboratory reagents, and consumer products, and the quality expectations attached to each differ. A certificate of analysis generally reports peptide purity by chromatography, copper content, appearance, and residual solvents or counterions. Counterion identity matters, because the complex is usually supplied as an acetate or a similar salt, and the counterion contributes to the measured mass. Independent verification of sequence and metal stoichiometry is advisable when a material is used for quantitative work. Batch-to-batch variation is common and should be documented rather than assumed negligible.
Copper peptide solutions tend to resist degradation better than many free peptides, because the bound metal protects the N-terminus and reduces susceptibility to some peptidases. Backbone hydrolysis, oxidation of the histidine imidazole ring, and photochemical reactions remain the principal degradation routes. Aqueous solutions are generally most stable near neutral to mildly acidic pH, while strongly alkaline conditions accelerate hydrolysis. Light exposure is usually avoided, since both the peptide and the copper center can take part in photochemical processes. Stability data published by suppliers often describe short-term behavior rather than multi-year shelf life.
Identity and purity are commonly assessed by reversed-phase high-performance liquid chromatography, frequently paired with mass spectrometry to confirm the molecular ion. Copper content is measured separately, typically by inductively coupled plasma mass spectrometry or atomic absorption spectroscopy, because the chromatographic signal reports the peptide rather than the metal. Ultraviolet-visible spectroscopy provides a fast check on complex formation, since copper(II) peptide complexes absorb in the visible region. Elemental analysis and amino acid analysis are used less often but remain useful for reference standards. A gap between reported peptide purity and measured copper content is a recurring source of confusion.
Stability of GHK-Cu is influenced by light, oxygen, moisture, pH, and temperature. Solid material is generally kept desiccated and frozen to reduce hydrolysis and oxidation, while aqueous solutions are best prepared fresh or stored cold in aliquots. Repeated freeze-thaw cycles can promote aggregation, precipitation, or peptide degradation. Copper coordination may change under strongly acidic or alkaline conditions, potentially altering the complex's spectroscopic properties. Published long-term stability data for specific matrices, such as cosmetic emulsions or biological buffers, are limited, so shelf-life claims should be treated as formulation-specific rather than universal.
Quality control for GHK-Cu relies on documentation and independent testing rather than a single accepted standard. A certificate of analysis may report peptide purity, copper content, residual solvents, water content, and microbial limits, but the underlying methods and acceptance criteria vary by supplier. Verification can include mass confirmation, amino acid analysis, and comparison with a reference standard when one is available. Open questions include how different copper-binding modes or peptide isomers affect measured activity and whether conventional purity assays capture those differences. Buyers of research-grade material typically need to request raw data rather than rely solely on a summary certificate.
Laboratory characterization of GHK-Cu typically combines separation, spectroscopic, and elemental techniques. Reverse-phase high-performance liquid chromatography is widely used to assess peptide purity, often with ultraviolet detection near the copper-related absorption band or with mass spectrometry for identity confirmation. Because the molecule contains copper, elemental methods such as inductively coupled plasma mass spectrometry or atomic absorption spectroscopy are used to quantify metal content and confirm stoichiometry. No single universal pharmacopeial monograph exists for GHK-Cu. Laboratories therefore validate their own methods, and reported purity values depend on the chosen assay and calibration standards.
Analytical verification typically combines reversed-phase high-performance liquid chromatography with ultraviolet-visible detection. The copper complex absorbs visible light near 600–630 nm, giving a characteristic blue signal. Mass spectrometry confirms molecular mass and can detect free peptide or mismatched copper stoichiometry. Copper content is often measured independently by inductively coupled plasma mass spectrometry or atomic absorption spectroscopy. Purity, counterion identity, and residual solvents are additional quality-control parameters that methods may address.
Solid GHK-Cu is generally stored as a dry powder under frozen conditions to limit degradation. The peptide bond can hydrolyze, and the copper center can be displaced by strong chelators such as EDTA. Aqueous solutions are less stable than the solid and may lose color or form precipitates over time. Temperature, pH, and oxygen exposure are the main variables that affect shelf life. Neutral to slightly acidic conditions tend to preserve the complex better than strongly alkaline media.
== Honors and awards == 1971 ACS Award in Chemical Instrumentation 1981 ACS Award in Analytical Chemistry 1984 William H. Nichols Medal 1985 Oesper Award 1985 J. J. Thomson Gold Medal by International Mass Spectrometry Society 1987 Pittsburgh Analytical Chemistry Award 1989 Field and Franklin Award for Mass Spectrometry 1989 University of Naples Gold Medal 1992 Robert Boyle Gold Medal by the Royal Society of Chemistry 1996 Chemical Pioneer Award from the American Institute of Chemists 1997 Bijvoet Medal of the Bijvoet Center for Biomolecular Research. 1999 J. Heyrovsky Medal by the Czech Academy of Sciences 2000 G. Natta Gold Medal by Italian Chemical Society 2001 Torbern Bergman Medal by the Swedish Chemical Society 2003 John B. Fenn Distinguished Contribution in Mass Spectrometry by the American Society for Mass Spectrometry (ASMS) 2004 Lavoisier Medal by the French Chemical Society 2006 Pehr Edman Award by the International Association for Protein Structure 2015 Nakanishi Prize from the American Chemical Society 2019 American Chemical Society designated a National Historic Chemical Landmark in Midland, MI for the demonstration of the first operating GC-MS by Fred McLafferty and Roland Gohlke.
On December 13, 2018, the teaser of the film Black Antenna featuring the song "Rainier Fog" was released on Alice in Chains' official YouTube channel, with drummer Sean Kinney stating; "We've always toyed with the idea of creating videos for every song on one of our albums. Not only did we do that for Rainier Fog, it got totally out of hand and we made a whole goddamn movie. Everything that will be seen in the videos will be footage from Black Antenna to preface the complete film's release." "Rainier Fog" was released as a single on February 26, 2019. The official trailer for Black Antenna was released on Alice in Chains' YouTube Channel on February 28, 2019. Besides a 90-minute film, a 10-part web-series focused on each track from the album was planned. Episodes 1 and 2, "The One You Know" and "Rainier Fog", respectively, were released on March 7, 2019. The tenth and last episode, "All I Am", was released on July 17, 2019. The official music video for "Rainier Fog" was released on YouTube on May 15, 2019, and was co-directed by Alice in Chains and Peter Darley Miller, who also directed the band's 2013 mockumentary, AIC 23. On December 1, 2020, Alice in Chains was honored with the Founders Award from Seattle's Museum of Pop Culture. The benefit concert featured tribute performances from artists such as Ann Wilson, Korn, Metallica, Fishbone, Dallas Green, Billy Corgan, Tad Doyle, members of Soundgarden and Pearl Jam, among others. The event was made available for streaming for free and raised more than $600,000 for the museum in its first night.
In the beginning of the 19th century the process of canning foods was mainly done by small canneries. These canneries were full of overlooked sanitation problems, such as poor hygiene and unsanitary work environments. Since the refrigerator did not exist and industrial canning standards were not set in place it was very common for contaminated cans to slip onto the grocery store shelves. According to The Fruits of Empire: Art, Food and the Politics of Race in the Age of American Expansion by Shana Klein, "Workers also suffered injuries, specifically bruised knuckles and open sores, from trimming and packaging pineapples. Gloves were one preventative measure to protect a canner's hands from the acidity of the pineapple, but gloves did not always help."
Two types of dried lotus seeds can be found commercially; brown peel and white. The former is harvested when the seed head of the lotus is ripe or nearly ripe and the latter is harvested when the seed head is still fully green but with almost fully developed seeds. White lotus seeds are de-shelled and de-membraned. At harvest, the bitter-tasting germ of most seeds is removed using a hollow needle. Brown peel lotus seeds are brown because the ripened seed has adhered to its membrane. The germ of these hard seeds is removed by cracking the seeds in half. Dried lotus seeds past their prime oxidize to a yellow brown color. However, some sellers of dried lotus seeds bleach their products with hydrogen peroxide, sodium hydroxide, or other chemicals.
== History == The thymus was known to the ancient Greeks, and its name has been suggested to come from the herb thyme (in Greek: θύμος), which became the name for a "warty excrescence", possibly due to its resemblance to a bunch of thyme. Alternatively, it has been suggested that its name comes from the ancient Greek “θύμος(thumos)” meaning soul or spirit due to the ancient belief that it was where the soul rested. Galen was the first to note that the size of the organ changed over the duration of a person's life. In the 19th century, a condition was identified as status thymicolymphaticus defined by an increase in lymphoid tissue and an enlarged thymus. It was thought to be a cause of sudden infant death syndrome but is now an obsolete term. The importance of the thymus in the immune system was discovered in 1961 by Jacques Miller, by surgically removing the thymus from one-day-old mice, and observing the subsequent deficiency in a lymphocyte population, subsequently named T cells after the organ of their origin. Until the discovery of its immunological role, the thymus had been dismissed as an "evolutionary accident", without functional importance. The role the thymus played in ensuring mature T cells tolerated the tissues of the body was uncovered in 1962, with the finding that T cells of a transplanted thymus in mice demonstrated tolerance towards tissues of the donor mouse. B cells and T cells were identified as different types of lymphocytes in 1968, and the fact that T cells required maturation in the thymus was understood.
Sources: en.wikipedia.org
As a result, for near-surface disease states, magnets should be placed downstream of the disease locus, and for intra-surface disease states, magnets should be placed upstream of the disease locus to maximize accumulation.
== Classification == The classification of dinosaur eggs is based on the structure of the egg shells viewed in thin section via microscope, although new techniques such as electron backscatter diffraction have been used. There are three main categories of dinosaur eggs: spherulitic (sauropods and hadrosaurs), prismatic, and ornithoid (theropods, including modern birds).
Study 402 patients saw an improvement of depressive symptoms compared to placebo as documented by a change in MADRS total score of 2.4. Study 401 was conducted solely in the United States while Study 404 was a global study and included patients from the US. Of the entire Study 404 population (381 patients), two-thirds were from Russia and Colombia. At the completion of the two monotherapy Phase III trials only Study 404 met its primary endpoint and one of its secondary endpoints. In Study 404, patients received 42 mg lumateperone once daily or placebo for six weeks. Study 404 patients saw an improvement of depressive symptoms compared to placebo as documented by a change in MADRS total score of 4.6.
Due to the stabilization of 7s electronic orbitals and destabilization of 6d ones caused by relativistic effects, Cn2+ is likely to have a [Rn]5f146d87s2 electronic configuration, using the 6d orbitals before the 7s one, unlike its homologues. The fact that the 6d electrons participate more readily in chemical bonding means that once copernicium is ionized, it may behave more like a transition metal than its lighter homologues, especially in the possible +4 oxidation state. In aqueous solutions, copernicium may form the +2 and perhaps +4 oxidation states. The diatomic ion Hg2+2, featuring mercury in the +1 oxidation state, is well-known, but the Cn2+2 ion is predicted to be unstable or even non-existent. Copernicium(II) fluoride, CnF2, should be more unstable than the analogous mercury compound, mercury(II) fluoride (HgF2), and may even decompose spontaneously into its constituent elements. As the most electronegative reactive element, fluorine may be the only element able to oxidize copernicium even further to the +4 and even +6 oxidation states in CnF4 and CnF6; the latter may require matrix-isolation conditions to be detected, as in the disputed detection of HgF4. CnF4 should be more stable than CnF2. In polar solvents, copernicium is predicted to preferentially form the CnF−5 and CnF−3 anions rather than the analogous neutral fluorides (CnF4 and CnF2, respectively), although the analogous bromide or iodide ions may be more stable towards hydrolysis in aqueous solution. The anions CnCl2−4 and CnBr2−4 should also be able to exist in aqueous solution.
The company has created special donut lines for various events, for example, creating soldier-themed doughnuts for National Doughnut Day on June 1 in Thailand, with funds benefitting military personnel in the country. In June 2013, Mister Donut in Thailand debuted the SushiDo, sushi-themed donuts created as a part of "a special sushi-themed menu." At the time, they had not been added to the menu in Japan or other countries. Options included "sweet donut versions of ebi, tamago, maguro, salmon, with sugary frosting replacing raw fish." For Halloween 2013, Mister Donut introduced Hello Kitty jack-o'-lantern doughnuts in pumpkin or strawberry flavors, as well as other seasonal pumpkin-flavored items, including pumpkin versions of their regular donut. As of 2014, the stores in El Salvador focused on a menu described as more "homey than foreign, offering national staples like pupusas and tamales alongside giant cream-filled doughnuts." There have also been items such as strawberry-glaze donuts. In April 2014, the company launched a croissant-style doughnut, which proved popular.
Sources: en.wikipedia.org
Leucine rich repeat containing 15 is a cell membrane-expressed protein. In humans it is encoded by the LRRC15 gene. It is located on chromosome 3 at 3q29. It belongs to the LRR superfamily, which is involved in cell–cell and cell–ECM interactions.
Binding curves describe the binding behavior of ligand to a protein. Curves can be characterized by their shape, sigmoidal or hyperbolic, which reflect whether or not the protein exhibits cooperative or noncooperative binding behavior respectively. Typically, the x-axis describes the concentration of ligand and the y-axis describes the fractional saturation of ligands bound to all available binding sites. The Michaelis Menten equation is usually used when determining the shape of the curve. The Michaelis Menten equation is derived based on steady-state conditions and accounts for the enzyme reactions taking place in a solution. However, when the reaction takes place while the enzyme is bound to a substrate, the kinetics play out differently. Modeling with binding curves are useful when evaluating the binding affinities of oxygen to hemoglobin and myoglobin in the blood. Hemoglobin, which has four heme groups, exhibits cooperative binding. This means that the binding of oxygen to a heme group on hemoglobin induces a favorable conformation change that allows for increased binding favorability of oxygen for the next heme groups. In these circumstances, the binding curve of hemoglobin will be sigmoidal due to its increased binding favorability for oxygen. Since myoglobin has only one heme group, it exhibits noncooperative binding which is hyperbolic on a binding curve.
If analytes are too small to generate a readable signal for determining concentration, the assay matrix can be modified. CD/DVD based assays utilize the optical properties of gold. Gold nanoparticle bioconjugates are tracers used to increase the sensitivity of the assay. The gold nanoparticles can be identified with photometric or plasmonic detectors. The smaller the nanoparticles are, the more sensitive the assay becomes. Silver enhancer solution is also used to increase the reflective properties of samples. Gold nanoparticles have catalytic properties which cause them to reduce silver ions to silver metal. The silver metal deposits on the analytes and causes signals to be amplified. Silver metal is more easily detectable by cameras, scanners, or other drives than is the analyte alone. Still, this enhancement procedure requires many additional reaction and washing steps which could lead to analytical errors.
Caesium-137 has a number of practical uses. In small amounts, it is used to calibrate radiation-detection equipment. In medicine, it is used in radiation therapy. In industry, it is used in flow meters, thickness gauges, moisture-density gauges (for density readings, with americium-241/beryllium providing the moisture reading), and in borehole logging devices. Caesium-137 is not widely used for industrial radiography because it is hard to obtain a very high specific activity material with a well defined (and small) shape, as caesium from used nuclear fuel contains stable caesium-133 and also long-lived caesium-135. Isotope separation is too costly compared to cheaper alternatives. Also, the higher specific activity caesium sources tend to be made from highly soluble caesium chloride (CsCl); as a result, if a radiography source were to be damaged, the risk of radioactive contamination is high. It is possible to make water-insoluble caesium sources (with ferrocyanides, for example) but their specific activity will be lower. Other chemically inert caesium compounds include caesium-aluminosilicate-glasses akin to the natural mineral pollucite. The latter has been used in demonstrations of chemically stable water-insoluble forms of nuclear waste for disposal in deep geological repositories. A large emitting volume will harm the image quality in radiography.
19 May A policies study review, based on a systematic examination of existing methane policies across sectors, concludes that both only "about 13% of methane emissions are covered by methane mitigation policies" and that the effectiveness of these policies "is far from clear". Researchers propose a methodological approach and quantifications for reparations from fossil fuel producers. Cross-disciplinary researchers propose academics make universities implement, leadingly, the plant-based dietary transition that an increasingly large and confirmed corpus of studies, to which these contributed to, concludes is vital (7 May). Metascience-related events Nature reports China has "overtaken the United States as the number one ranked country or territory for contributions to research articles published in the Nature Index group of high-quality natural-science journals", remaining at second place overall. The Nature Index, since 2016, evaluates contribution by the number of articles published in a subgroup of their journals – other potential or less popular approaches and metrics for quantifications of success or impact can or could produce different rankings or annual tables and conclusions. 34% of neuroscience papers and 23% of medical papers published in 2020 were probably fabricated or plagiarized, according to a preprint study, stemming from paper mills (9 May). A time-use research study (10 May) estimates the costs of manuscript (re)formatting to fit journal guidelines, ~$230 million or ~75 million hours of lost academics' time in 2021.
Sources: en.wikipedia.org
It is the copper complex of the tripeptide glycyl-L-histidyl-lysine. The metal ion is held by the histidine imidazole group and the peptide N-terminus. Most research on it concerns skin and wound models.
The tripeptide was first isolated from human plasma and has also been reported in saliva and urine. Plasma levels appear to decline with age in some small studies. Those observations rest on limited sample sizes.
It is not authorized as a systemic medicine in most countries. Cosmetic preparations list it as an ingredient rather than an active pharmaceutical substance. Legal status therefore differs by jurisdiction.
Peptide content is usually measured by reverse-phase high-performance liquid chromatography, while copper is measured by atomic spectroscopy. Mass spectrometry can confirm the peptide identity and detect copper adducts. Combining these methods gives a more complete picture.