Everything below concerns ICP-MS. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2025-10-14. Where a claim depends on a specific study, the study is described rather than over-claimed.
Routine handling calls for minimizing freeze-thaw cycles and preparing solutions shortly before use. Glass or inert plastic containers reduce adsorption and metal leaching. Working stocks are often kept at 2–8 °C for short periods, while long-term reference material stays at −20 °C or below. Light protection is prudent because prolonged exposure may accelerate oxidation of the peptide. Documentation of lot number, concentration, and preparation date supports reproducibility in laboratory work.
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.
The sequence carries three residues in the order glycine, histidine, lysine, which places a small, flexible chain around a single metal centre. Compared with larger copper-binding proteins, the complex is compact and its coordination chemistry can be reproduced with synthetic peptide in a laboratory. Published structural work agrees on the nitrogen donor set but differs in the exact geometry assigned under some conditions, so the arrangement is best treated as well characterised in outline rather than fixed in every detail.
GHK-Cu is a coordination complex formed between the tripeptide glycyl-L-histidyl-L-lysine and a copper(II) ion. The peptide was isolated from human plasma in the early 1970s by Loren Pickart, who observed that a plasma fraction from young donors stimulated growth in cultured liver cells. The copper-bound form is abbreviated GHK-Cu, while the metal-free peptide is written simply as GHK. In the research literature the complex also appears as copper tripeptide-1 and as glycyl-histidyl-lysine copper complex.
| Property | Value | Notes |
|---|---|---|
| Physical state | Blue-violet solid | Typically supplied as lyophilized powder |
| Storage temperature | −20 °C or below | Desiccated, protected from light |
| Working stability | Hours to days at 2–8 °C | Depends on concentration and buffer |
| Identity test | RP-HPLC with UV-Vis | Visible absorbance near 600–630 nm |
| Copper assay | ICP-MS or AAS | Metal content confirms stoichiometry |
The compound entered scientific literature in the 1970s, when plasma factors with copper-binding activity were isolated and characterized. Later work expanded into wound healing, skin biology, and cosmetic formulation, where copper tripeptide-1 became a recognized ingredient name. Most published studies remain preclinical or small-scale, and findings are often reported in specialized dermatology or peptide journals. Regulatory treatment varies: some jurisdictions allow it as a cosmetic ingredient, while research-grade material is sold for laboratory use. Questions about optimal delivery, target tissues, and long-term effects continue to be investigated rather than settled.
GHK-Cu is a coordination complex formed between the tripeptide glycyl-L-histidyl-L-lysine and a copper(II) ion. The peptide sequence is often abbreviated Gly-His-Lys, and the copper is bound through the histidine imidazole nitrogen and adjacent peptide nitrogens. The complex is frequently described as a 1:1 peptide-to-copper species. It occurs naturally in human plasma, saliva, and urine at low concentrations. Its endogenous levels have been reported to decline with age, although the precise physiological role of that change remains an open question.
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.
Stability of GHK-Cu in solution depends on pH, temperature, buffer composition, and oxygen exposure. The copper center can undergo reduction or dissociation, especially in the presence of strong metal chelators such as EDTA. Aqueous solutions are often prepared fresh or stored frozen to limit degradation. Lyophilized solid is more stable than liquid formulations, but it can absorb moisture and should be kept dry. Light exposure may also affect copper complexes, though the effect is often modest.
Analytical confirmation usually combines a separation method with a copper-specific measurement. Liquid chromatography or mass spectrometry establishes peptide identity and purity, while an elemental measurement quantifies the metal content. A frequent misconception is that any blue solution contains an intact copper peptide complex; color alone does not confirm structure, because free copper salts and degraded mixtures can also appear colored. Literature on efficacy is mixed, with in vitro findings often more dramatic than human evidence, and reviews note small sample sizes and short follow-up. Open questions include optimal concentration, skin penetration, and long-term effects.
Proposed mechanisms for copper peptide activity center on delivery of copper ions to cells and on peptide fragments acting as signaling molecules. Copper is a cofactor for enzymes involved in collagen cross-linking and antioxidant defense, and the peptide may improve its availability at target sites. Separately, the tripeptide and its breakdown products have been reported to influence gene expression in cultured fibroblasts. Much of this evidence comes from laboratory cell cultures and animal models rather than controlled human trials. The relative contribution of the copper ion and the peptide sequence is therefore not fully settled.
Stability depends on temperature, light exposure, moisture, and the presence of oxidizing or reducing agents. Solid material held dry and protected from light is generally more stable than aqueous solutions, which can undergo gradual degradation. Recommended storage in much of the literature is a freezer at around minus twenty degrees Celsius for long-term retention, with working aliquots kept cold and shielded from light. Repeated freeze-thaw cycles and alkaline pH are commonly noted as factors that accelerate loss of the intact complex, though exact degradation rates vary.
Identity and purity are normally checked by reversed-phase high-performance liquid chromatography, often coupled to mass spectrometry. The peptide absorbs in the ultraviolet region, and the copper complex also shows a broad visible absorption band that can be followed spectroscopically. Copper content is measured separately, for example by inductively coupled plasma mass spectrometry or atomic absorption spectroscopy, because the peptide assay alone does not confirm how much metal is bound. Purity figures therefore need a stated basis: peptide peak area, copper content, or both.
Aqueous GHK-Cu solutions are less stable than the dry powder. Light, dissolved oxygen and elevated temperature all accelerate loss of the intact complex, and the main observable changes are fading of the blue colour and the appearance of peptide fragments. Acidic conditions protonate the histidine imidazole and weaken copper binding, while strongly alkaline conditions promote hydrolysis of the peptide backbone. Because several degradation routes operate at once, a single shelf-life figure does not describe all storage conditions.
Solid material is typically kept as a lyophilised powder in a sealed, light-protected container at minus 20 degrees Celsius, with desiccant where humidity is high. Working solutions are often prepared fresh, aliquoted and frozen to avoid repeated freeze-thaw cycles. Glassware and buffers are checked for trace metal contamination, since other transition metals can displace copper. Records of lot number, reconstitution date and storage temperature help trace unexpected colour changes. Blue colour itself is not a reliable purity test, because partly degraded solutions can remain visibly coloured.
==== New Jersey ==== In 2007 the New Jersey Department of Environmental Protection (NJDEP) announced that it found PFOA at "elevated levels in the system's drinking water near DuPont's massive Chambers Works chemical plant". In 2018 the state published a drinking water standard for PFNA. Public water systems in New Jersey are required to meet a maximum contaminant level (MCL) standard of 13 ppt. In 2019 New Jersey filed lawsuits against the owners of two plants that had manufactured PFASs (the Chambers Works and the Parlin plant in Sayreville), and two plants that were cited for water pollution from other chemicals. The companies cited are DuPont, Chemours and 3M. In 2020 the NJDEP set a PFOA standard at 14 ppt and a PFOS standard at 13 ppt.
=== Legal status === The US Food and Drug Administration (FDA) approved tranexamic acid oral tablets (brand name Lysteda) for the treatment of heavy menstrual bleeding in November 2009. In March 2011, the status of tranexamic acid for the treatment of heavy menstrual bleeding was changed in the UK, from POM (Prescription only Medicines) to P (Pharmacy Medicines) and became available over the counter in UK pharmacies under the brand names of Cyklo-F and Femstrual.
== CDAs in NMR spectroscopy == CDAs are used with NMR spectroscopic analysis to determine enantiomeric excess and the absolute configuration of a substrate. Chiral discriminating agents are sometimes difficult to distinguish from chiral solvating agents (CSA) and some agents can be used as both. The speed of the exchange between the substrate and the metal center is the most important determining factor to differentiate between the use of a compound as a CDA or CSA. Generally, a CDA has a slow exchange whereas a CSA has a fast exchange. CDAs are more widely used than CSAs to determine absolute configurations because the covalent bonding to the substrate and auxiliary reagent produce species with greater conformational rigidity which creates greater differences in the NMR spectra. CDAs and CSAs can be used together to improve chiral recognition, although this is not a common. NMR shift reagents such as EuFOD, Pirkle's alcohol, and TRISPHAT take advantage of the formation of diastereomeric complexes between the shift reagent and the analytical sample.
== August 2013 interim report and governance charges == On 2 August 2013, almost seven months into the investigation, ASADA released an interim report to the AFL and Essendon Football Club. The interim report made no findings regarding the legality of the supplements program, but highlighted a wide range of governance and duty-of-care failures related to the program. On 13 August 2013, based on the interim report, AFL general counsel Andrew Dillon charged Essendon with "conduct that is unbecoming or likely to prejudice the interests or reputation of the Australian Football League or to bring the game of football into disrepute, contrary to AFL Rule 1.6". The charges included:
=== United States herbalism fraud === Over the years 2017–2021, the US Food and Drug Administration (FDA) issued warning letters to numerous herbalism companies for illegally marketing products under "conditions that cause them to be drugs under section 201(g)(1) of the Act [21 U.S.C. § 321(g)(1)], because they are intended for use in the diagnosis, cure, mitigation, treatment, or prevention of disease and/or intended to affect the structure or any function of the body" when no such evidence existed. During the COVID-19 pandemic, the FDA and US Federal Trade Commission issued warnings to several hundred American companies for promoting false claims that herbal products could prevent or treat COVID-19 disease.
Sources: en.wikipedia.org
==== NADP ==== Nicotinamide adenine dinucleotide phosphate is a coenzyme present in redox and biosynthetic reactions. The domain binds NADP in its oxidised or reduced forms as NADP+ or NADPH respectively.
Under the partitioning powers, economic diversification and progress, including large-scale industrialisation, were introduced in the traditionally agrarian Polish lands, but this development turned out to be very uneven. Advanced agriculture was practiced in the Prussian Partition, except for Upper Silesia, where the coal-mining industry created a large labor force. The densest network of railroads was built in German-ruled western Poland. In Russian Congress Poland, a striking growth of industry, railways and towns took place, all against the background of an extensive, but less productive agriculture. The industrial initiative, capital and know-how were provided largely by entrepreneurs who were not ethnic Poles. Warsaw (a metallurgical center) and Łódź (a textiles center) grew rapidly, as did the total proportion of urban population, making the region the most economically advanced in the Russian Empire (industrial production exceeded agricultural production there by 1909). The coming of the railways spurred some industrial growth even in the vast Russian Partition territories outside of Congress Poland. The Austrian Partition was rural and poor, except for the industrialized Cieszyn Silesia area. Galician economic expansion after 1890 included oil extraction and resulted in the growth of Lemberg (Lwów, Lviv) and Kraków. Economic and social changes involving land reform and industrialization, combined with the effects of foreign domination, altered the centuries-old social structure of Polish society.
=== Threats to quality === TMA (tristeza y muerte de agave – "agave depression and death") is a blight that has reduced the production of the agave grown to produce tequila. This has resulted in lower production and higher prices throughout the early 21st century, and due to the long maturation of the plant, will likely continue to affect prices for years to come.
The transit time of red blood cells from capillaries and the release of steroid hormones from red blood cells are both very rapid, so it is suggested that progesterone is delivered through circulation to tissues via red blood cells without having time to equilibrate with systemic blood. This could potentially explain the low levels of progesterone in venous blood in spite of very high levels in capillary blood and saliva. However, one study assessed progesterone levels in red blood cells with transdermal progesterone and found that they were significantly increased but still very low. Nonetheless, according to other authors, "[a]lthough the investigators of that study concluded that the progesterone levels in red blood cells were too low to be important in the delivery of progesterone to target tissues, it should be realized that even small amounts of progesterone taken up by red blood cells might be important because the transit time of red blood cells from capillaries is very rapid. [...] However, the role of red blood cells in steroid hormone transport has not been studied thoroughly, and such studies are warranted." An in vitro study using porcine skin and several formulations of transdermal progesterone found that only minute quantities of progesterone penetrated through the skin but that there was significant partitioning of progesterone in the skin tissues. According to the researchers, the results suggested that lymphatic circulation in the skin might account for systemic distribution of transdermal progesterone.
Plant sources of proteins include legumes, nuts, seeds, grains, and some vegetables and fruits. Plant foods with protein concentrations greater than 7% include (but are not limited to) soybeans, lentils, kidney beans, white beans, mung beans, chickpeas, cowpeas, lima beans, pigeon peas, lupines, wing beans, almonds, Brazil nuts, cashews, pecans, walnuts, cotton seeds, pumpkin seeds, hemp seeds, sesame seeds, and sunflower seeds. Photovoltaic-driven microbial protein production uses electricity from solar panels and carbon dioxide from the air to create fuel for microbes, which are grown in bioreactor vats and then processed into dry protein powders. The process makes highly efficient use of land, water and fertiliser.
Sources: en.wikipedia.org
== External links == [1]: A MATLAB routine to solve the linear elastic contact mechanics problem entitled; "An LCP solution of the linear elastic contact mechanics problem" is provided at the file exchange at MATLAB Central. [2]: Contact mechanics calculator. [3]: detailed calculations and formulae of JKR theory for two spheres. [5]: A Matlab code for Hertz contact analysis (includes line, point and elliptical cases). [6]: JKR, MD, and DMT models of adhesion (Matlab routines).
=== Animals and aquaculture === Various studies on spirulina as an alternative feed for animal and aquaculture have been done. Spirulina can be fed up to 10% for poultry and less than 4% for quail. An increase in spirulina content up to 40 g/kg (0.64 oz/lb) for 16 days in 21-day-old broiler male chicks resulted in yellow and red coloration of flesh, possibly due to the accumulation of the yellow pigment zeaxanthin. Pigs and rabbits can receive up to 10% of the feed and increase in the spirulina content in cattle resulted in increase in milk yield and weight. Spirulina has been established as an alternative feedstock and immune booster for bigmouth buffalo, milk fish, cultured striped jack, carp, red sea bream, tilapia, catfish, yellow tail, zebrafish, shrimp, and abalone, and up to 2% spirulina per day in aquaculture feed can be safely recommended.
== Barium-131 == Barium-131 is a radioactive isotope of barium with a half-life of 11.52 days. It decays to caesium-131 by electron capture. It is produced by irradiation of caesium with protons with the reaction 133Cs(p,3n)131Ba. It is developed for SPECT imaging and can be combined with the alpha-emitter radium-223.
==== Seed oil ==== Mature seeds yield 38–40% edible oil called ben oil from its high concentration of behenic acid. The refined oil is clear and odorless, and resists rancidity. The young fruits can be boiled and the oil skimmed off the water surface. The seed cake remaining after oil extraction may be used as a fertilizer or as a flocculent to purify water. Moringa seed oil also has potential for use as a biofuel.
backbone Also main chain. The primary or most structurally significant portion of a molecule with respect to its other parts, functional groups, moieties, or substituents; or, in the case of a polymer, that linear chain of atoms to which all other chains, long or short or both, may be regarded as being pendant or as side chains. Where two or more chains might equally be considered the backbone, the one which permits the simplest representation of the molecule in chemical formulae and nomenclature is considered the backbone.
Sources: en.wikipedia.org
Dry powder is typically stored frozen at −20 °C or lower, protected from moisture and light. Short-term working amounts may be kept refrigerated. Avoiding repeated temperature changes helps preserve the material.
Reversed-phase HPLC with UV-visible detection is common because the copper complex absorbs visible light. Mass spectrometry provides molecular mass confirmation. Copper-specific methods such as ICP-MS quantify the metal content.
The blue color comes from copper-ligand interactions. Displacement of copper by chelators or changes in pH can shift or diminish the color. Such changes often indicate that the complex has been altered.
It consists of a three-amino-acid peptide, glycine-histidine-lysine, bound to one copper(II) ion. The peptide supplies four nitrogen donor atoms, and the resulting complex is stable in neutral aqueous solution. The metal-free peptide is usually called GHK.