If you have been reading about HPLC 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.
Last reviewed on 2025-09-05. Where a claim depends on a specific study, the study is described rather than over-claimed.
Analytical laboratories commonly use high-performance liquid chromatography to separate creatine from creatinine and related impurities. Ion chromatography, nuclear magnetic resonance, and titration assays can also quantify the compound. Water content is measured by Karl Fischer titration or loss on drying, because the monohydrate has a defined theoretical water fraction. Particle size, bulk density, and flowability are physical properties that affect blending and capsule filling. These measurements support quality control and help verify that a lot matches its specification.
Regulatory status varies by country. In the United States, creatine monohydrate is sold as a dietary supplement ingredient, while in the European Union it is placed on the market as a food supplement component. Some jurisdictions have established purity monographs or permitted health claims, while others treat it as a novel food or require notification. Product labels may state the amount of creatine monohydrate or the equivalent creatine content, and the two figures can differ. Independent testing programs sometimes check identity, potency, and contaminant limits.
Creatine monohydrate is stable under dry, cool conditions but can degrade when exposed to moisture and heat. In solution, it undergoes hydrolysis to creatinine, a cyclic derivative with little role in phosphagen energy transfer. The rate of conversion increases with temperature, storage time, and acidic or alkaline pH. Solid material kept in a sealed container at room temperature generally retains its composition for extended periods. Moisture uptake is a primary concern because it can accelerate breakdown and caking.
Creatine was first identified in skeletal muscle extracts in the nineteenth century, and its role in phosphagen energy buffering was clarified in the twentieth century. The monohydrate salt became widely studied after methods for inexpensive synthesis and crystallization were developed. Modern research examines its effects on muscle energetics, recovery, and cognitive performance under specific conditions. Findings vary with population, exercise protocol, baseline creatine status, and measurement method. Studies often compare supplementation with placebo during controlled training or testing schedules.
Creatine monohydrate is a hydrated form of creatine, a nitrogen-containing compound involved in cellular energy metabolism. Its molecular formula is C4H9N3O2·H2O, with a molar mass around 149.15 g/mol. The monohydrate is the most common solid form used in research and commercial settings because it crystallizes readily and remains stable under ordinary conditions. The term monohydrate indicates one water molecule per creatine molecule in the crystal lattice. It appears as a white crystalline powder with low odor.
| Property | Value | Notes |
|---|---|---|
| Typical storage temperature | 15-25 °C | Sealed container; protect from moisture and direct heat. |
| Theoretical water content | About 12.1% | One water molecule per creatine molecule. |
| Primary degradation product | Creatinine | Formed by cyclization, especially in aqueous solution. |
| Common analytical method | HPLC-UV | Used to separate creatine from creatinine and related impurities. |
| Regulatory classification (U.S.) | Dietary supplement ingredient | Other jurisdictions may classify it as a food supplement or novel food depending on rules. |
In the body, creatine is synthesized from the amino acids arginine, glycine, and methionine, primarily in the liver and kidneys. It is transported to muscle and other tissues, where it is phosphorylated to phosphocreatine by creatine kinase. This phosphagen system provides a rapid source of adenosine triphosphate during short, intense contractions. Dietary creatine comes mainly from meat and fish, and the body's total pool is influenced by both synthesis and intake.
As a supplement, creatine monohydrate is studied for its effects on muscle performance and recovery. The compound is often described as an ergogenic aid, meaning it may support physical work capacity. Research typically compares it with placebo or other forms, such as citrate or nitrate, under controlled conditions. Questions remain about the optimal dose and long-term effects in different populations, and findings are not uniform across all studies. The monohydrate form remains the most extensively tested.
Creatine monohydrate is the hydrated form of creatine, a nitrogen-containing organic acid involved in cellular energy transfer. Its molecular formula is C4H11N3O3, and it consists of creatine plus one water molecule in the crystal lattice. The anhydrous base, creatine, has the formula C4H9N3O2. The compound appears as a white, odorless, crystalline powder and is classified as a guanidine derivative. It is distinct from creatinine, a breakdown product measured in clinical chemistry.
In animals, creatine is synthesized mainly in liver, kidney, and pancreas from arginine, glycine, and methionine. The first committed step transfers a guanidino group from arginine to glycine, forming guanidinoacetate. Subsequent methylation by S-adenosylmethionine yields creatine. Dietary sources include meat and fish; endogenous synthesis supplies part of the body pool. Most creatine is stored in skeletal muscle, where it is converted to phosphocreatine and participates in rapid regeneration of adenosine triphosphate during short, intense activity.
Dry creatine monohydrate is generally stable when kept sealed and protected from heat and moisture. In solution, however, creatine undergoes a slow cyclization to creatinine, a related compound with no role in phosphocreatine storage. The rate of this conversion increases with temperature and is influenced by pH. Because creatinine is a common impurity in liquid or poorly stored products, analytical testing often measures both compounds. The crystalline monohydrate is less prone to degradation than aqueous preparations, though caking can occur if moisture enters the container.
Laboratory analysis of creatine monohydrate typically uses high-performance liquid chromatography to separate creatine from creatinine and other impurities. Detection may be ultraviolet, refractive index, or mass spectrometric, depending on the laboratory's equipment and the required sensitivity. Nuclear magnetic resonance spectroscopy can quantify the main component and identify related substances. Water content is measured by Karl Fischer titration, which is important because the monohydrate has a defined theoretical hydration level. Heavy metals, residual solvents, and microbial limits are also checked in quality control programs.
Commercial creatine monohydrate is produced mainly by chemical synthesis rather than extraction from animal tissue. Suppliers provide a certificate of analysis listing assay, water content, and impurity limits, and some products undergo third-party testing. Verification of identity can use infrared or Raman spectroscopy alongside chromatographic methods. Storage recommendations generally call for a cool, dry place and a tightly closed container to limit moisture uptake. Open questions include how packaging, flavoring agents, and long-term storage affect the stability of finished products.
Creatine monohydrate is a crystalline organic compound formed from creatine and water in a one-to-one ratio. It belongs to the guanidino family and contains a methylated guanidine group attached to an acetate-like chain. The solid is commonly described as a white, odorless powder with a mildly bitter taste. Its molecular formula is C4H11N3O3·H2O, and the hydrated form is the most widely traded grade. The compound occurs naturally in vertebrate muscle and brain tissue, where it participates in rapid energy buffering.
In aqueous solution, creatine monohydrate exists mainly as a zwitterion, carrying both a positive guanidinium charge and a negative carboxylate charge. This charge separation raises water solubility relative to many neutral organic solids and helps explain its behavior in analytical separations. The monohydrate can lose its water of crystallization under sustained heat or low humidity, converting toward anhydrous creatine. Such transitions matter for mass balance calculations because the hydrate contributes water mass that is not part of the active creatine molecule.
One common division of Raleigh is to differentiate the central part of the city, which lies inside of the circumferential highway known as the Raleigh Beltline (I-440 and I-40) from areas outside of the Beltline. The area inside of the beltline includes the entirety of the central business district known as Downtown Raleigh, as well as several more residential areas surrounding it. The downtown area is home to historic buildings such as the Sir Walter Raleigh Hotel built in the early 20th century, the restored City Market, the Fayetteville Street downtown business district (which includes the PNC Plaza and Wells Fargo Capitol Center buildings), as well as the North Carolina Museum of History, North Carolina Museum of Natural Sciences, North Carolina State Capitol, William Peace University, the City of Raleigh Museum, Raleigh Convention Center, Shaw University, Campbell University School of Law, and St. Augustine's College. In the 2000s, an effort by the Downtown Raleigh Alliance was made to separate this area of the city into five smaller districts: Fayetteville Street, Moore Square, Glenwood South, Warehouse, and Capital District. The nearby Blount Street Historic District includes many of the city's historic Victorian, Georgian Revival, Queen Anne, and Second Empire mansions, including Norris-Heartt House, Andrews-Duncan House, Heck-Andrews House, Bailey-Tucker House, Capehart House, Bailey-Bunn House, and the Garland Scott and Toler Moore Tucker House (the latter was later moved from its original location to Oakwood).
=== Transmission === The reason for this increased HBV infection is unknown, because hepatitis B has no clear transmission routes in many people in China, although both neonatal infection and horizontal transmission during early childhood are still the most common routes. During and before the Cultural revolution many of the cases came from re-used needles that were contaminated with HBV.
=== Recreational use === Illicit use of pharmaceutical fentanyl and its analogues first appeared in the mid-1970s in the medical community and continues in the present. More than 12 different analogues of fentanyl, all unapproved and clandestinely produced, have been identified in the U.S. drug traffic. In February 2018, the US Drug Enforcement Administration indicated that illicit fentanyl analogs have no medically valid use, and thus applied a "Schedule I" classification to them. Fentanyl analogues may be hundreds of times more potent than heroin. Fentanyl is used orally, smoked, snorted, or injected. Fentanyl is sometimes sold as heroin or oxycodone, which can lead to overdose. Many fentanyl overdoses are initially classified as heroin overdoses. Estonia has the highest rate of 3-methylfentanyl overdose deaths in the EU, due to its high rate of recreational use. Another form of fentanyl that has appeared on the streets is the Actiq lollipop formulation. The pharmacy retail price ranges from US$15 to US$50 per unit based on the strength of the lozenge, with the black market cost ranging from US$5 to US$25 in 2007, depending on the dose. The attorneys general of Connecticut and Pennsylvania have launched investigations into its diversion from the legitimate pharmaceutical market, including Cephalon's "sales and promotional practices for Provigil, Actiq and Gabitril." Non-medical use of fentanyl by individuals without opioid tolerance can be very dangerous and has resulted in numerous deaths. Even those with opiate tolerances are at high risk for overdoses.
=== Metabolic labeling === Many metabolic chemical reporters have been developed to identify O-GlcNAc. Metabolic chemical reporters are generally sugar analogues that bear an additional chemical moiety allowing for additional reactivity. For example, peracetylated GlcNAc (Ac4GlcNAz) is a cell-permeable azido sugar that is de-esterified intracellularly by esterases to GlcNAz and converted to UDP-GlcNAz in the hexosamine salvage pathway. UDP-GlcNAz can be utilized as a sugar donor by OGT to yield the O-GlcNAz modification. The presence of the azido sugar can then be visualized via alkyne-containing bioorthogonal chemical probes in an azide-alkyne cycloaddition reaction. These probes can incorporate easily identifiable tags such as the FLAG peptide, biotin, and dye molecules. Mass tags based on polyethylene glycol (PEG) have also been used to measure O-GlcNAc stoichiometry. Conjugation of 5 kDa PEG molecules leads to a mass shift for modified proteins - more heavily O-GlcNAcylated proteins will have multiple PEG molecules and thus migrate more slowly in gel electrophoresis. Other metabolic chemical reporters bearing azides or alkynes (generally at the 2 or 6 positions) have been reported. Instead of GlcNAc analogues, GalNAc analogues may be used as well as UDP-GalNAc is in equilibrium with UDP-GlcNAc in cells due to the action of UDP-galactose-4'-epimerase (GALE). Ac4GalNAz shows enhanced labeling of O-GlcNAc versus Ac4GlcNAz, possibly due to a bottleneck in UDP-GlcNAc pyrophosphorylase processing of GlcNAz-1-P to UDP-GlcNAz.
Eusociality is the highest level of social organization. These societies have an overlap of adult generations, the division of reproductive labor and cooperative caring of young. Usually insects, such as bees, ants and termites, have eusocial behavior, but it is demonstrated in two rodent species: the naked mole-rat and the Damaraland mole-rat. Presociality is when animals exhibit more than just sexual interactions with members of the same species, but fall short of qualifying as eusocial. That is, presocial animals can display communal living, cooperative care of young, or primitive division of reproductive labor, but they do not display all of the three essential traits of eusocial animals. Humans and some species of Callitrichidae (marmosets and tamarins) are unique among primates in their degree of cooperative care of young. Harry Harlow set up an experiment with rhesus monkeys, presocial primates, in 1958; the results from this study showed that social encounters are necessary in order for the young monkeys to develop both mentally and sexually. A fission–fusion society is a society that changes frequently in its size and composition, making up a permanent social group called the "parent group". Permanent social networks consist of all individual members of a community and often varies to track changes in their environment. In a fission–fusion society, the main parent group can fracture (fission) into smaller stable subgroups or individuals to adapt to environmental or social circumstances.
Sources: en.wikipedia.org
== Interactions == Alprazolam is primarily metabolized via CYP3A4. Combining CYP3A4 inhibitors such as cimetidine, erythromycin, norfluoxetine, fluvoxamine, itraconazole, ketoconazole, nefazodone, propoxyphene, and ritonavir delay the hepatic clearance of alprazolam, which may result in its accumulation and increased severity of its side effects. Imipramine and desipramine have been reported to increase an average of 31% and 20% respectively by the concomitant administration of alprazolam tablets. Combined oral contraceptive pills reduce the clearance of alprazolam, which may lead to increased plasma levels of alprazolam and accumulation. Alcohol is one of the most common interactions; alcohol and alprazolam taken in combination have a synergistic effect on one another, which can cause severe sedation, behavioral changes, and intoxication. The more alcohol and alprazolam taken, the worse the interaction. Similarly, the use of prescribed or illicit opioids with alprazolam can cause life-threatening respiratory depression. Combination of alprazolam with the herb kava can result in the development of a semi-comatose state. Plants in the genus Hypericum, including St. John's wort, conversely can lower the plasma levels of alprazolam and reduce its therapeutic effect.
During pregnancy, thiamine is sent to the fetus via the placenta. Pregnant women have a greater requirement for the vitamin than other adults, especially during the third trimester. Pregnant women with hyperemesis gravidarum are at an increased risk of thiamine deficiency due to losses when vomiting. In lactating women, thiamine is delivered in breast milk even if it results in thiamine deficiency in the mother. Thiamine is important not only for mitochondrial membrane development, but also for synaptic membrane function. It has also been suggested that a deficiency hinders brain development in infants and may be a cause of sudden infant death syndrome.
Although, the 2 newspapers had links with the elites of their countries, and shared the commitment to vindicate the prevailing ideologies in the Criollo oligarchies (economic and political liberalism) in tune with the modernizing trends of the time. They also differed in their points of view to conceive of Americanism, being clearly distant in their approaches. While El Mercurio was totally convinced in promoting the cause of American solidarity, without making distinctions between brother and equal countries, La Nación, for its part, expressed contempt for these excessively fraternal tendencies, invoking the dichotomy between civilization and barbarism as a criterion to privilege before defining the American cause (presenting himself to the civilized Argentine and Uruguayan society as opposed to Paraguayan and Peruvian barbarism), to justify his actions in the war against Paraguay, as well as the repression of the liberal Buenos Aires government to the conservative uprisings through the interior of the country; They also wanted to legitimize the Eurocentric tendencies present in the Argentine elite and their unreserved acceptance of the prevailing social Darwinism, where Peruvian society (and the mestizo heritage in Latin America in general) was frowned upon for not being majority white societies, generating contempt. Also, during the 1978 FIFA World Cup, it was reported that the Argentine dictator, Jorge Rafael Videla, tried to psychologically frighten the Peruvian soccer team by entering the team's locker room, shortly before the soccer match between Peru and Argentina.
=== The Scar Free Foundation === In 2016, The Healing Foundation officially rebranded as The Scar Free Foundation. This change was made following a detailed assessment of previous work and future priorities with clinicians, scientists, Partner Member Organisations, and people with lived experience of scarring. The charity pivoted to focus exclusively on wound healing and scarring conditions. A new Research Strategy was developed by a panel chaired by Professor Sir John Iredale. Brendan Eley was succeeded as CEO by Richard Nugee in April 2023.
Sources: en.wikipedia.org
In all the places where they pretend to have the graveclothes, they show a large piece of linen by which the whole body, including the head, was covered, and, accordingly, the figure exhibited is that of an entire body. But the Evangelist John relates that Christ was buried, "as is the manner of the Jews to bury". What that manner was may be learned, not only from the Jews, by whom it is still observed, but also from their books, which explain what the ancient practice was. It was this: The body was wrapped up by itself as far as the shoulders, and then the head by itself was bound round with a napkin, tied by the four corners, into a knot. And this is expressed by the Evangelist, when he says that Peter saw the linen clothes in which the body had been wrapped lying in one place, and the napkin which had been wrapped about the head lying in another. The term napkin may mean either a handkerchief employed to wipe the face, or it may mean a shawl, but never means a large piece of linen in which the whole body may be wrapped. I have, however, used the term in the sense which they improperly give to it. On the whole, either the Evangelist John must have given a false account, or every one of them must be convicted of falsehood, thus making it manifest that they have too impudently imposed on the unlearned. Although pieces said to be of burial cloths of Jesus are held by at least four churches in France and three in Italy, none has gathered as much religious following as the Shroud of Turin.
The predictions of the effects of a major countervalue nuclear exchange include millions of city dweller deaths within a short period of time. Some 1980s predictions had gone further and argued that a full-scale nuclear war could eventually bring about human extinction. Such predictions, sometimes but not always based on total war with nuclear arsenals at Cold War highs, received contemporary criticism. On the other hand, some 1980s governmental predictions, such as FEMA's CRP-2B and NATO's Carte Blanche, have received criticism from groups such as the Federation of American Scientists for being overly optimistic. CRP-2B, for instance, predicted that 80% of Americans would survive a nuclear exchange with the Soviet Union, a figure that neglected nuclear war's impacts on healthcare infrastructure, the food supply, and the ecosystem and assumed that all major cities could be successfully evacuated within 3–5 days. A number of Cold War publications advocated preparations that could purportedly enable a large proportion of civilians to survive even a total nuclear war. Among these is Nuclear War Survival Skills. To avoid injury and death from a nuclear weapon's heat flash and blast effects, the two most common causes of injury from nuclear weapons, schoolchildren were taught to duck and cover by the early Cold War film of the same name. Such advice is once again being given in case of nuclear terrorist attacks.
== Structure and active site == Apamin is a polypeptide possessing an amino acid sequence of H-Cys-Asn-Cys-Lys-Ala-Pro-Glu-Thr-Ala-Leu-Cys-Ala-Arg-Arg-Cys-Gln-Gln-His-NH2 (one-letter sequence CNCKAPETALCARRCQQH-NH2, with disulfide bonds between Cys1-Cys11 and Cys3-Cys15). Apamin is very rigid because of the two disulfide bridges and seven hydrogen bonds. The three-dimensional structure of apamin has been studied with several spectroscopical techniques: HNMR, Circular Dichroism, Raman spectroscopy, FT-IR. The structure is presumed to consist of an alpha-helix and beta-turns, but the exact structure is still unknown. By local alterations it is possible to find the amino acids that are involved in toxicity of apamin. It was found by Vincent et al. that guanidination of the ε-amino group of lysine4 does not decrease toxicity. When the ε-amino group of lysine4 and the α-amino group of cysteine1 are acetylated or treated with fluorescamine, toxicity decreases with a factor of respectively 2.5 and 2.8. This is only a small decrease, which indicates that neither the ε-amino group of lysine4 nor the α-amino group of cysteine1 is essential for the toxicity of apamin. Glutamine7 was altered by formation of an amide bond with glycine ethyl ester, this resulted in a decrease in toxicity of a factor 2.0. Glutamine7 also doesn't appear to be essential for toxicity. When histidine18 is altered by carbethoxylation, toxicity decreases only by a factor 2.6.
Sources: en.wikipedia.org
A sealed container at room temperature, away from moisture and direct heat, is suitable for most solid material. Keeping the lid closed limits water uptake and caking. Long-term storage in a refrigerator is not necessary if the powder remains dry.
Heat, moisture, and prolonged time in solution promote conversion to creatinine. The reaction is faster at higher temperatures and at pH values far from neutral. Dry powder is much more stable than dissolved material.
Common methods include high-performance liquid chromatography for creatine and creatinine, plus water-content analysis by Karl Fischer titration. Heavy metals, residual solvents, and microbial limits may also be tested. A specification may list total creatine content and impurity limits.
Creatine is the base compound, while creatine monohydrate is a solid crystalline form that contains one water molecule per creatine molecule. Once dissolved, the monohydrate dissociates and releases creatine, which can participate in cellular energy metabolism. The monohydrate is the form most commonly used in research and commercial products.