If you have been reading about Certificate of analysis and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Updated 2026-01-07. Numbers and descriptions here follow the published literature rather than marketing material.
Identity and purity of selank are established with reversed-phase high-performance liquid chromatography coupled to mass spectrometry. The peptide elutes from C18 columns with acetonitrile gradients in water containing trifluoroacetic acid or formic acid, and detection is usually performed by ultraviolet absorbance near 214 nm. Electrospray ionization in positive mode gives a doubly protonated ion near m/z 377, consistent with a mass of about 752 Da. Amino acid analysis or tandem mass spectrometry of fragment ions confirms the sequence. Because the molecule has no aromatic residues, it lacks a usable 280 nm chromophore, so low-wavelength detection or mass spectrometry is required.
Peptide bonds in selank are susceptible to hydrolysis under strongly acidic or basic conditions, and the terminal proline residues are vulnerable to exopeptidase activity in biological samples. Lyophilized powder stored dry at -20 °C typically remains stable for extended periods, whereas aqueous solutions degrade faster and may lose measurable purity within days to weeks depending on pH, temperature, and microbial load. Repeated freeze-thaw cycles promote aggregation and adsorption to container surfaces. For analytical work, solutions are usually prepared fresh, kept cold, and used within a single working day.
Dry powder is normally held at -20 degrees Celsius or lower, in a sealed container with desiccant and protection from light. Reconstituted solutions are usually kept at 2 to 8 degrees Celsius for short periods and frozen for longer ones. Proline residues at several positions are generally associated with some resistance to peptidase attack, but chemical stability still declines at neutral to alkaline pH and at elevated temperature. Exact shelf-life figures are product-specific and are not standardised across suppliers.
Identity and purity are usually assessed by reversed-phase high-performance liquid chromatography, with mass spectrometry used to confirm molecular mass and sequence information. Amino acid analysis and peptide mapping may supplement these methods. Certified reference standards are scarce, and many commercial lots are sold as research chemicals without a pharmacopoeial monograph. Regulatory treatment differs by country: Selank is a registered prescription medicine in Russia, while in the European Union and the United States it is not an approved drug and may fall under research-chemical or unapproved-product frameworks.
| Property | Value | Notes |
|---|---|---|
| Identity confirmation | Reversed-phase HPLC retention time versus reference standard | Retention depends on column, gradient, and ion-pairing agent |
| Mass confirmation | Electrospray or MALDI mass spectrometry | Doubly protonated ion near m/z 377 is consistent with about 752 Da |
| Typical purity specification | 95 percent or higher by chromatographic peak area | Lower values suggest truncated or modified peptide species |
| Storage of lyophilized powder | -20 °C, desiccated, protected from light | Powder tolerates long storage better than solution |
| Storage of solution | 2-8 °C for short periods | Freeze-thaw cycling promotes aggregation and surface adsorption |
Regulatory status differs sharply by region. Selank holds a Russian marketing authorization, where it is supplied mainly as nasal drops, while authorities elsewhere have not approved it for medical use. Material sold internationally is therefore usually labeled as a research chemical rather than a medicine. Peer-reviewed publications come predominantly from Russian laboratories, and sample sizes are generally small. Whether the compound produces comparable effects under independent, well-controlled replication remains an open question that the broader literature has not settled.
Selank is a synthetic heptapeptide developed in Russia as a structural analogue of tuftsin, a naturally occurring immunomodulatory tetrapeptide. Its sequence, Thr-Lys-Pro-Arg-Pro-Gly-Pro, keeps the tuftsin core at the N-terminus and appends a Pro-Gly-Pro tail. Researchers at the Institute of Molecular Genetics in Moscow synthesized the compound during the 1990s while searching for peptides with combined anxiolytic and immunomodulatory activity. The added tail was intended to resist enzymatic cleavage and prolong the molecule's presence in circulation.
The compound has a calculated molecular weight near 751.9 daltons and carries a net positive charge at physiological pH because of its arginine residue. It dissolves freely in water and in common aqueous buffers, and typically appears as a white or off-white lyophilized powder. The amide backbone makes the molecule susceptible to peptidases, which limits oral use and favors intranasal or parenteral routes. Nomenclature in the literature varies: the substance is also described by the sequence abbreviation TP-7 and by a Russian trade designation.
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.
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.
===== Satisfaction with Life Scale ===== "Happiness" encompasses different emotional and mental phenomena. One method of assessment is Ed Diener's Satisfaction with Life Scale. According to Diener, this five-question survey corresponds well with impressions from friends and family, and low incidence of depression. Rather than long-term, big picture appraisals, some methods attempt to identify the amount of positive affect from one activity to the next. Scientists use beepers to remind volunteers to write down the details of their current situation. Alternatively, volunteers complete detailed diary entries each morning about the day before. A discrepancy arises when researchers compare the results of these short-term "experience sampling" methods, with long-term appraisals. Namely, the latter may not be very accurate; people may not know what makes their life pleasant from one moment to the next. For instance, parents' appraisals mention their children as sources of pleasure, while "experience sampling" indicates parents were not enjoying caring for their children, compared to other activities. Psychologist Daniel Kahneman explains this discrepancy by differentiating between happiness according to the "experiencing self" compared to the "remembering self": when asked to reflect on experiences, memory biases like the Peak-End effect (e.g. we mostly remember the dramatic parts of a vacation, and how it was at the end) play a large role. A striking finding was in a study of colonoscopy patients.
=== Biological strategies === It has become possible to accelerate natural aerobic, anaerobic, and sequential aerobic and/or anaerobic biological processes to minimize the presence of NAPLs in the subsurface environment. Most bioremediation strategies rely on the presence of specific populations of bacteria/microorganisms and the addition of organic carbon to stimulate biodegradation. This organic carbon can be supplied via injection of soluble organic carbon sources such as lactate, alcohols, cheese whey, etc. and placement of slow-release electron donors such as vegetable oil and soybean oil emulsions. Sufficient dissolved oxygen must be present for aerobic biodegradation, which can be supplied through strategies including air sparging and SVE. That said, the ability to supply sufficient oxygen is a limiting factor affecting the success of this type of remediation strategy. Also, many cases require the presence of inducers such as methane, propane, ammonia, or toluene, which are contaminants in and of themselves that are inherently harmful to the subsurface environment. Yet another challenge is maintaining a sufficient population of bacteria/microorganisms in the face of competition from native bacteria and other external pressures. There is also regulatory pushback to the use of genetically modified bacteria. Furthermore, NAPLs may not be readily bioavailable, limiting the effectiveness of biodegradation strategies. In this sense, biodegradation may not be appropriate as a single solution, but it can certainly be used in conjunction with other strategies.
Non-selective beta-blockers: propranolol, nadolol, timolol Beta-1-selective beta-blockers: atenolol, bisoprolol, metoprolol, esmolol Beta-blockers with vasodilating effect: labetalol, carvedilol, nebivolol Beta-blockers with intrinsic sympathomimetic activity: acebutolol, pindolol Some common side effects include increased airway resistance for non-selective beta-blockers, exacerbation of peripheral vascular diseases, and hypotension Beta-blockers are contraindicated in patients with second- or third-degree atrioventricular block. In particular, beta-blockers with intrinsic sympathomimetic activity are contraindicated in patients with myocardial infarction, heart failure or severe bradycardia. Beta-blockers should be used with caution in patients with asthma or chronic obstructive pulmonary disease (COPD) due to bronchoconstriction, and in patients with diabetes mellitus (DM) due to masking of hypoglycaemia.
The new 26th district is based in the northwestern corner of the Dallas–Fort Worth metroplex, centering on southern and eastern Denton County (including the county's share of Carrollton along with all of Lewisville, Flower Mound and Little Elm) and including Cooke County (Gainesville) and the southern two-thirds of Wise County including Decatur. The incumbent is Republican Brandon Gill, who was elected with 62.1% of the vote in 2024. That same year, the district gave 61.2% of the vote to Donald Trump and 58.4% to Ted Cruz.
Sources: en.wikipedia.org
A trephine (a circular cutting device), which removes a circular disc of cornea, is used by the surgeon to cut the donor cornea. A second trephine is then used to remove a similar-sized portion of the patient's cornea. The donor tissue is then sewn in place with sutures. Antibiotic eyedrops are placed, the eye is patched, and the patient is taken to a recovery area while the effects of the anesthesia wear off. The patient typically goes home following this and sees the doctor the following day for the first postoperative appointment.
Using Mendeleev's nomenclature for unnamed and undiscovered elements, oganesson is sometimes known as eka-radon (until the 1960s as eka-emanation, emanation being the old name for radon). In 1979, IUPAC assigned the systematic placeholder name ununoctium to the undiscovered element, with the corresponding symbol of Uuo, and recommended that it be used until after confirmed discovery of the element. Although widely used in the chemical community on all levels, from chemistry classrooms to advanced textbooks, the recommendations were mostly ignored among scientists in the field, who called it "element 118", with the symbol of E118, (118), or simply 118. Before the retraction in 2001, the researchers from Berkeley had intended to name the element ghiorsium (Gh), after Albert Ghiorso (a leading member of the research team). The Russian discoverers reported their synthesis in 2006. According to IUPAC recommendations, the discoverers of a new element have the right to suggest a name. In 2007, the head of the Russian institute stated the team were considering two names for the new element: flyorium, in honor of Georgy Flyorov, the founder of the research laboratory in Dubna; and moskovium, in recognition of the Moscow Oblast where Dubna is located. He also stated that although the element was discovered as an American collaboration, who provided the californium target, the element should rightly be named in honor of Russia since the Flyorov Laboratory of Nuclear Reactions at JINR was the only facility in the world which could achieve this result.
== Product == The extract is available commercially as Calocurb, an oral dietary supplement for appetite management which was launched in New Zealand in 2018. The capsule has an enteric coating to pass through the stomach and allow delivery to the small intestine.
=== Commonwealth period === From 1914 to 1927, parts of Western Negros hosted several newly established settlements which became cities connected by railroads constructed to flow towards several "sugar centrals" which were processing the extremely sweet raw sugar canes grown in Negros' volcanic soil and farmed by several "Haciendas". These haciendas littered the countryside as the central sugar mills eventually grew to become full pledged towns and cities: chief among which were Ilog, Hinigaran, La Carlota, Silay, Pulupandan, Bacolod, San Carlos and Bais. Western Negros also saw massive immigration from Panay as the Spanish, Chinese, and French mestizos, plus others, who were serving in the Haciendas imported laborers from Panay island to foster the farming of Negros' sugar plantations and thereby displacing the Cebuano speaking natives. Soon, vast numbers of immigrants from Spain, most of them Basques, became Negros' plantation owners. The east side of Negros was not as thickly settled but became a center of education as on 9 April 1901, the Second Philippine Commission under the chairmanship of William H. Taft arrived in Dumaguete. Weeks later on 1 May, the civil government under American sovereignty was established, and on 28 August, Dr. David S. Hibbard founded what is now Silliman University the first American school in the Philippines and the entire Asian continent with the help of Meliton Larena as the first Mayor of Dumaguete, as well as Demetrio Larena.
=== Acidification === Potassium hydrogen sulfate (also known as potassium bisulfate), KHSO4, is readily produced by reacting K2SO4 with sulfuric acid. It forms rhombic pyramids, which melt at 197 °C (387 °F). It dissolves in three parts of water at 0 °C (32 °F). The solution behaves much as if its two congeners, K2SO4 and H2SO4, were present side by side of each other uncombined; an excess of ethanol the precipitates normal sulfate (with little bisulfate) with excess acid remaining. The behavior of the fused dry salt is similar when heated to several hundred degrees; it acts on silicates, titanates, etc., the same way as sulfuric acid that is heated beyond its natural boiling point does. Hence it is frequently used in analytical chemistry as a disintegrating agent. For information about other salts that contain sulfate, see sulfate.
Sources: en.wikipedia.org
In the final day of the visit, Trump visited Zhongnanhai, where they strolled around Jinggu garden. When asked by Trump if he brought other dignitaries into the Zhongnanhai, Xi replied "Very few, we usually don't hold diplomatic events here. Even after we started having some, it's still extremely rare", while adding Russian president Vladimir Putin had visited several times. Xi and Trump later held talks in Chun'ouzhai pavilion. In a press briefing, Trump said they "settled a lot of different problems that other people wouldn't have been able to solve". Xi said the Zhongnanhai "is the place where leaders of the party and the central government of China work and live, including myself" and added "After the founding of the People's Republic of China in 1949, we have been here, including Chinese leaders: Mao Zedong, Zhou Enlai, Deng Xiaoping, Jiang Zemin, Hu Jintao and so on". He said "This place used to be part of the imperial garden, there is a lot of history in this compound" and noted one of the trees Xi and Trump saw in the garden was 490 years old, adding "In other places within this compound, there are trees that have lived to be over 1,000 years old". Xi also said he would send seeds of the Chinese roses he and Trump saw in the garden to Trump as a gift. After his visit to the Zhongnanhai, Trump left for Beijing Capital International Airport, where he embarked on Air Force One and left China. White House staffers and reporters were required to surrender various items obtained in China prior to boarding Air Force One.
Organic chemists use the tools of thermodynamics to study the bonding, stability, and energetics of chemical systems. This includes experiments to measure or determine the enthalpy (ΔH), entropy (ΔS), and Gibbs' free energy (ΔG) of a reaction, transformation, or isomerization. Chemists may use various chemical and mathematical analyses, such as a Van 't Hoff plot, to calculate these values. Empirical constants such as bond dissociation energy, standard heat of formation (ΔfH°), and heat of combustion (ΔcH°) are used to predict the stability of molecules and the change in enthalpy (ΔH) through the course of the reactions. For complex molecules, a ΔfH° value may not be available but can be estimated using molecular fragments with known heats of formation. This type of analysis is often referred to as Benson group increment theory, after chemist Sidney Benson who spent a career developing the concept. The thermochemistry of reactive intermediates—carbocations, carbanions, and radicals—is also of interest to physical organic chemists. Group increment data are available for radical systems. Carbocation and carbanion stabilities can be assessed using hydride ion affinities and pKa values, respectively.
Dopamine receptors (subtypes D1, D2, D3 and D4), which account for its different antipsychotic properties on productive and unproductive symptoms, in the mesolimbic dopamine system accounts for the antipsychotic effect whereas the blockade in the nigrostriatal system produces the extrapyramidal effects Serotonin receptors (5-HT2, 5-HT6 and 5-HT7), with anxiolytic, antidepressant and antiaggressive properties as well as an attenuation of extrapyramidal side effects, but also leading to weight gain and ejaculation difficulties. Histamine receptors (H1 receptors, accounting for sedation, antiemetic effect, vertigo, and weight gain) α1- and α2-adrenergic receptors (accounting for sympatholytic properties, lowering of blood pressure, reflex tachycardia, vertigo, sedation, hypersalivation and incontinence as well as sexual dysfunction, but may also attenuate pseudoparkinsonism – controversial. Also associated with weight gain as a result of blockage of the adrenergic alpha 1 receptor as well as with intraoperative floppy iris syndrome due to its effect on the iris dilator muscle. M1 and M2 muscarinic acetylcholine receptors (causing anticholinergic symptoms such as dry mouth, blurred vision, constipation, difficulty or inability to urinate, sinus tachycardia, electrocardiographic changes and loss of memory, but the anticholinergic action may attenuate extrapyramidal side effects). The presumed effectiveness of the antipsychotic drugs relied on their ability to block dopamine receptors.
== Career == Butler began as an instructor of medicine at Yale University (1994–1995) and later served as assistant professor at Vanderbilt University (1999–2006), where he was medical director of both the Heart Transplant and heart-lung transplant programs. In 2007, he joined Emory University as a full professor of medicine and director of the Heart Failure Research Program. At Stony Brook University, Butler served as Director of Cardiovascular Medicine and co-director of the Heart Institute (2014–2017), where he held the Charles A. Gargano Chair in Cardiology. From 2018 to 2022, he chaired the Department of Medicine at the University of Mississippi Medical Center, where he was also a professor of Physiology and Biophysics and held the Patrick H. Lehan Chair in Cardiovascular Research. Butler has combined clinical work with research, education, and leadership, directing heart failure and transplant programs at Vanderbilt and Tennessee Valley Healthcare systems. He served as Deputy Chief Science Officer for the American Heart Association (AHA) from 2009 to 2016. He has chaired committees for the Heart Failure Society of America and the American College of Cardiology, and represented the U.S. on the European Society of Cardiology Heart Failure Guidelines panel. Butler is a Fellow of the AHA, ACC, HFSA, and ESC. Butler chairs the U.S. Food and Drug Administration's Cardio-Renal Advisory Committee, co-chairs the NIH-funded HeartShare study on heart failure progression, and serves as principal investigator for several international cardiovascular trials.
== Preparation == An aqueous solution of sodium silicate is acidified to produce a gelatinous precipitate that is washed, then dehydrated to produce colorless silica gel. When a visible indication of the moisture content of the silica gel is required, ammonium tetrachlorocobaltate(II) (NH4)2[CoCl4] or cobalt(II) chloride CoCl2 is added. This will cause the gel to be blue when dry and pink when hydrated. Due to a link between the cobalt chloride and cancer, it has been forbidden in Europe for use in silica gel. An alternative indicator is methyl violet, which is orange when dry and green when hydrated.
Sources: en.wikipedia.org
Identity is confirmed by matching the retention time in reversed-phase chromatography against a reference standard and by measuring the molecular mass with mass spectrometry. Tandem mass spectrometry or amino acid analysis can verify the sequence of the seven residues. Because the peptide contains no aromatic amino acids, detection at 280 nm is not useful.
Lyophilized powder is normally stored desiccated at -20 °C, protected from light and moisture. Powder kept under these conditions is generally stable for long periods. Solutions are less stable and are usually prepared immediately before use.
A purity value from one chromatographic method does not capture every possible impurity. Related peptides with similar retention behavior, counterions, and residual solvents may not appear in the same analysis. Independent testing with an orthogonal method provides stronger assurance of identity and content.
Dry powder is normally held at -20 degrees Celsius or below in a sealed, light-protected container with desiccant. Brief room-temperature handling during weighing is generally tolerated. Storage instructions vary between suppliers, so the accompanying certificate of analysis should be followed.