Certificate of analysis 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 2026-06-21. Where a claim depends on a specific study, the study is described rather than over-claimed.
Once dissolved, the peptide is markedly less stable than the dry powder. Aqueous solutions are subject to backbone hydrolysis and to microbial growth when they are handled without sterile technique. Buffered solutions near neutral pH are common for short-term laboratory work, while acidic conditions are sometimes used to improve solubility. Analytical laboratories generally prepare working solutions fresh rather than storing them, and a residual water film left in a reopened vial can seed degradation even when the container appears dry.
Reversed-phase high-performance liquid chromatography is the standard technique for estimating peptide purity. The result is a peak-area percentage, which describes how much of the detected material elutes as the main peak in one run. Mass spectrometry confirms the molecular mass and can reveal truncated, adducted, or otherwise modified species. Amino acid analysis or tandem mass spectrometry can address sequence fidelity when identity is in doubt. None of these measurements, taken alone, establishes that a sample is fit for any specific purpose.
Published work on this peptide almost always uses intranasal delivery, with drops or a spray applied to the nasal mucosa. Some animal experiments have used subcutaneous or intraperitoneal injection, and a smaller number have compared routes directly. Oral administration is not a focus of the literature, because short peptides of this size are broken down by digestive enzymes and cross intestinal barriers poorly. How much of an intranasal dose reaches the bloodstream intact in humans remains an open question.
Animal studies have examined behaviour in tests of anxiety, memory retention and stress response, and several report changes in neurotrophic or neurotransmitter-related markers. The human evidence base is much smaller, consisting mainly of short trials conducted in Russia with limited reporting in English-language journals. Sample sizes are modest and outcome measures vary between studies, so the findings are best described as preliminary. Independent replication under modern trial standards has not been widely reported.
Outside its country of origin the compound is generally handled as a research chemical rather than an approved medicine. No regulatory approval from the United States Food and Drug Administration or the European Medicines Agency has been granted for human use. Identity and purity are normally checked by reverse-phase high-performance liquid chromatography, with mass spectrometry used to confirm the molecular mass. Lyophilised material is stored cold and desiccated, and repeated freeze-thaw cycles are avoided.
| Property | Value | Notes |
|---|---|---|
| Typical purity specification | 95 percent or higher by RP-HPLC | Area percentage of the main peak |
| Identity confirmation | Electrospray ionization mass spectrometry | Observed mass compared with the theoretical value near 751.9 Da |
| Recommended dry storage | -20 °C, desiccated | -80 °C for multi-year archival material |
| Solution handling | Prepare fresh; avoid long storage | Sterile filtration reduces microbial load |
| Common synonyms | TKPRPGP; TP-7 | Sequence code and laboratory designation used interchangeably |
Selank is a synthetic heptapeptide developed in Russia during the 1990s. Researchers at the Institute of Molecular Genetics of the Russian Academy of Sciences designed it as a stabilized analog of tuftsin, a naturally occurring immunomodulatory tetrapeptide. The compound has been studied primarily for its reported anxiolytic and nootropic effects. It remains largely unknown in Western pharmacology and is not approved as a medicine by major regulators such as the FDA or the EMA.
The primary structure of Selank is Thr-Lys-Pro-Arg-Pro-Gly-Pro, corresponding to the molecular formula C33H57N11O9 and a monoisotopic mass of roughly 751.9 daltons. The N-terminal threonine and the arginine residue in the fourth position are shared with tuftsin, which carries the sequence Thr-Lys-Pro-Arg. The three additional residues at the C-terminus, Pro-Gly-Pro, extend the chain and are associated with greater resistance to enzymatic degradation. This extension also separates Selank from the shorter parent peptide.
Naming conventions place Selank in the same research family as Semax, another Russian-developed peptide investigated for cognitive effects. The two compounds share a lineage but differ in sequence and in the biological systems proposed as their targets. Semax descends from ACTH fragments, whereas Selank descends from tuftsin. Publications sometimes identify Selank by its full peptide sequence or by laboratory codes rather than one uniform trade name. Because replication outside Russia is limited, reports on its properties are best read alongside the study design and the purity of the material tested.
Selank is a synthetic heptapeptide developed in Russia. Its sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, a seven-residue chain built around the natural tetrapeptide tuftsin. Researchers at the Institute of Molecular Genetics of the Russian Academy of Sciences first described the compound in the mid-1990s. The design combined the tuftsin core with an added Pro-Gly-Pro tail, a modification intended to extend the molecule's stability in biological fluids. Published work on the peptide has appeared mainly in Russian-language journals.
Reported activity for Selank centers on anxiolytic and nootropic effects. Russian clinical reports describe use in anxiety and in cognitive or attention-related complaints. Most of this evidence comes from studies conducted by the same research groups that developed the peptide. Independent replication in other countries remains limited, and no major Western regulatory agency has approved the compound for any indication. The gap between local reports and external verification is a recurring point in discussions of the peptide.
In 1999, National Semiconductor also put out feelers for selling if not the whole, then a majority stake of, its fabrication plant in South Portland, Maine. However, that did not come to fruition. On June 28, 2000, National Semiconductor and TSMC Taiwan signed an agreement that would allow transfer of advanced fabrication technologies from TSMC to the National Semiconductor fabrication plant in South Portland, Maine. On March 11, 2009, National announced plans to close its assembly and test plant in Suzhou, China, and its wafer fabrication plant in Arlington, Texas. On October 9, 2009, Brian Halla announced his retirement as National's CEO. He remains executive chairman. The company promoted Donald (Don) Macleod, who had previously served as the company's president and chief operating officer, to CEO.
== Formal oxidation states for pyrite, marcasite, molybdenite and arsenopyrite == From the perspective of classical inorganic chemistry, which assigns formal oxidation states to each atom, pyrite and marcasite are probably best described as Fe2+[S2]2−. This formalism recognizes that the sulfur atoms in pyrite occur in pairs with clear S−S bonds. These persulfide [−S−S−] units can be viewed as derived from hydrogen disulfide, H2S2. Thus pyrite would be more descriptively called iron persulfide, not iron disulfide. In contrast, molybdenite, MoS2, features isolated sulfide S2− centers and the oxidation state of molybdenum is Mo4+. The mineral arsenopyrite has the formula FeAsS. Whereas pyrite has [S2]2− units, arsenopyrite has [AsS]3− units, formally derived from deprotonation of arsenothiol (H2AsSH). Analysis of classical oxidation states would recommend the description of arsenopyrite as Fe3+[AsS]3−.
Tertiary structure may give way to the formation of quaternary structure in some proteins, which usually involves the "assembly" or "coassembly" of subunits that have already folded; in other words, multiple polypeptide chains could interact to form a fully functional quaternary protein.
Sources: en.wikipedia.org
Herbal medicine (also called herbalism, phytomedicine or phytotherapy) is the study of pharmacognosy and the use of medicinal plants, which are a basis of traditional medicine. Scientific evidence for the effectiveness of many herbal treatments remains limited, prompting ongoing regulatory evaluation and research into their safety and efficacy. Standards for purity or dosage are generally not provided. The scope of herbal medicine sometimes includes fungal and bee products, as well as minerals, shells and certain animal parts. Paraherbalism is the pseudoscientific use of plant or animal extracts as medicine, relying on unproven beliefs about the safety and effectiveness of minimally processed natural substances. Herbal medicine has been used since at least the Paleolithic era, with written records from ancient Sumer, Egypt, Greece, China, and India documenting its development and application over millennia. Modern herbal medicine is widely used globally, especially in Asia and Africa. Traditional medicine systems involve long-standing, culturally-embedded practices using local herbs, animal products, and spiritual elements. These systems have influenced and contributed to modern pharmacology. Herbalists believe that plants, having evolved defenses against environmental stressors, produce beneficial phytochemicals, often extracted from roots or leaves, that can be used in medicine.
As a result, Sir Robert Fraser of the ITA declared that the only acceptable forms of advertising on ITV were those clearly intended to promote sales of the product or services in question, and that "[advertising] designed to influence public opinion during a takeover battle or a campaign against nationalization on behalf of private enterprise — however well disguised — would in future be disallowed." In 1994, Lyons Original Coffee hired the advertising agency Duckworth Finn Grubb Waters (DFGW), who created an innovative UK television advert that aimed "to turn a commercial break into a coffee break." Employing an interactive "datablast" technique, the advert depicts scans of 30 pages from women's magazines, such as Cosmopolitan, Elle and Good Housekeeping, displayed at the rate of five frames a second, and the advert invites viewers to record the commercial on a VCR, play it back and then repeatedly pause it, one frame at a time, to read the pages while sat with a cup of Lyons coffee, with the advertisement providing "30 minutes of magazine 'reading' in 30 seconds." Considered groundbreaking, the advertisement premiered on Channel 4 on 7 November 1994, and was compared other nascent forms of interactive advertising from the same year, such as HHCL's commercials for the Mazda 323, one of which similarly invited viewers to record it and play it back and pause at specific moments, allowing to read otherwise momentary information about the car and a competition to win one.
This theory treats all individuals as rational operators, committing criminal acts after consideration of all associated risks (detection and punishment) compared with the rewards of crimes (personal, financial etc.). Little emphasis is placed on the offenders' emotional state. The role of criminal organizations in lowering the perceptions of risk and increasing the likelihood of personal benefit is prioritized by this approach, with the organization's structure, purpose, and activity being indicative of the rational choices made by criminals and their organizers.
Sources: en.wikipedia.org
== Uses == Whey is used to produce whey cheeses such as ricotta, Norwegian brunost, and whey butter and many other products for human consumption. The fat content of whey is low; 1,000 pounds of whey are required to make a few pounds of whey butter. It is also an additive in many processed foods, including breads, crackers, and commercial pastry, and in animal feed. Whey proteins consist primarily of α-lactalbumin and β-lactoglobulin. Sweet whey contains glycomacropeptide (GMP). It is also an abundant source of lactose which can further be used for the synthesis of lactose-based bioactive molecules. Dairy whey remaining from home-made cheesemaking has many uses. It is a dough conditioner and can be substituted for skimmed milk in most baked good recipes that require milk (bread, pancakes, muffins, etc.). Throughout history, whey was a popular drink in inns and coffee houses. When Joseph Priestley was at college at Daventry Academy, 1752–1755, he records that, on the morning of Wednesday, 22 May 1754, he "went with a large company to drink whey." This was probably "sack whey" or "wine whey". Whey is also one of the main ingredients of Rivella, a carbonated drink in Switzerland. In areas where cheese is made, excess whey byproduct is sometimes sprayed over hay fields as a fertilizer. Historically whey, being a byproduct of cheese making, was considered a waste product and was pumped into rivers and streams in the U.S. Since the whey contained protein, this practice led to the growth of large concentrations of algae.
=== Therapeutic foods === Due in part to limited research on supplementary feeding, there is little evidence that this strategy is beneficial. A 2015 systematic review of 32 studies found that there are limited benefits when children under 5 receive supplementary feeding, especially among younger, poorer, and more undernourished children. However, specially formulated foods do appear to be useful in treating moderate acute malnutrition in the developing world. These foods may have additional benefits in humanitarian emergencies, since they can be stored for years, can be eaten directly from the packet, and do not have to be mixed with clean water or refrigerated. In young children with severe acute malnutrition, it is unclear if ready-to-use therapeutic food differs from a normal diet. Severely malnourished individuals can experience refeeding syndrome if fed too quickly. Refeeding syndrome can result regardless of whether food is taken orally, enterally or parenterally. It can present several days after eating with potentially fatal heart failure, dysrhythmias, and confusion. Some manufacturers have fortified everyday foods with micronutrients before selling them to consumers. For example, flour has been fortified with iron, zinc, folic acid, and other B vitamins like thiamine, riboflavin, niacin and vitamin B12. Baladi bread (Egyptian flatbread) is made with fortified wheat flour. Other fortified products include fish sauce in Vietnam and iodized salt.
==== Rise in oxygen levels theory for multicellularity ==== Despite the fact that organisms had the potential to become multicellular it is likely that it was not actually possible until the late Neoproterozoic. This is because multicellularity requires oxygen, and before the late Neoproterozoic there was very limited oxygen availability. After the melting of the “Snowball Earth” during the mid Neoproterozoic, nutrients that were trapped in the ice flooded the oceans. Surviving bacteria flourished due to the increased nutrient levels. Among these microbes were cyanobacteria and other oxygen producing bacteria, which led to the massive rise in oxygen levels. The increased oxygen availability allowed it to be used by cells in order to manufacture collagen. Collagen is the key component for cell aggregation, It is a rope-like molecule that “ties” cells together. Oxygen is required for collagen synthesis because ascorbic acid (Vitamin C) is essential for this process to occur. A key component in the ascorbic acid molecule is oxygen (chemical formula C6H8O6). Therefore, it is evident that the rise in oxygen is a crucial step to the rise of multicellularity since it is essential for the synthesis of collagen.
Sources: en.wikipedia.org
Sealed, desiccated storage at -20 °C or colder is the standard recommendation for research-grade material. Vials should reach room temperature before they are opened, which limits condensation. Repeated temperature cycling is discouraged.
A reported purity value reflects the share of the main peak in one chromatographic run and says nothing about identity. Confirming that the expected sequence is present requires a separate measurement such as mass spectrometry. Purity and identity are distinct questions.
A mass spectrum reports the molecular masses present in a sample and shows whether they match the value expected for selank, near 751.9 Da. It also flags common artifacts such as truncation or adduct formation. It does not establish correct stereochemistry or complete sequence order on its own.
Most published work uses intranasal application, either as drops or as a nasal spray. Injection routes appear in a smaller set of animal experiments. Oral use is uncommon in the literature because peptide breakdown and poor absorption limit this route.