HPLC 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.
Updated 2026-04-08. Numbers and descriptions here follow the published literature rather than marketing material.
Commercial creatine products appear in several forms, including monohydrate, hydrochloride, citrate, nitrate, and ethyl ester. Creatine monohydrate is the most studied form and serves as a reference material in comparative research. Different forms vary in solubility, pH, and water content, but they share creatine as the active moiety after dissolution. Claims that one form is uniformly superior remain debated, and study designs often differ in population, exercise protocol, and outcome measures. Purity and hydration state are central to interpreting product labels.
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.
Creatine monohydrate is one of several solid forms of creatine described in the literature. Other forms include anhydrous creatine, creatine hydrochloride, and creatine ethyl ester, each with different solubility and stability characteristics. The monohydrate is distinct from creatinine, a spontaneous breakdown compound that forms when creatine loses water and cyclizes. Commercial descriptions sometimes use synonyms such as methylguanidoacetic acid or N-(aminoiminomethyl)-N-methylglycine, which refer to the same base molecule. These names appear in chemical databases and product labels.
Creatine monohydrate is a crystalline compound formed when one molecule of creatine binds with one molecule of water. Creatine itself is a nitrogen-containing organic acid involved in cellular energy transfer, particularly in muscle and nerve tissue. The monohydrate form is the most common solid form used in research and commercial products because it is relatively stable and easy to handle. Its molecular formula is C4H9N3O2·H2O, and its molar mass is about 149.15 grams per mole.
In the human body, creatine is synthesized mainly in the liver and kidneys from the amino acids glycine, arginine, and methionine. Dietary sources include meat, fish, and other animal tissues, which supply preformed creatine. Because plant foods contain little or no creatine, dietary intake varies widely among populations. The compound is stored largely in skeletal muscle, where it is converted to phosphocreatine and used to regenerate adenosine triphosphate during short bursts of activity.
| Property | Value | Notes |
|---|---|---|
| Chemical formula (monohydrate) | C4H11N3O3 | Includes one water molecule per creatine unit. |
| Molecular weight | 149.15 g/mol | Calculated for the monohydrate; anhydrous creatine is 131.13 g/mol. |
| Appearance | White crystalline powder | Odorless; particle size can vary by manufacturing. |
| CAS Registry Number | 6020-87-7 | Identifies creatine monohydrate; creatine base is 57-00-1. |
| Common synonyms | Creatine hydrate; methylguanidoacetic acid monohydrate | Naming varies by registry and supplier. |
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.
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.
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.
The term creatine monohydrate is often shortened to creatine in casual usage, though other creatine forms exist, including citrate, nitrate, and hydrochloride salts. These alternative forms differ in solubility, pH behavior, and the amount of creatine delivered per unit mass. Regulatory categories vary by country: some jurisdictions treat it as a food ingredient, while others place it under supplement or drug frameworks depending on claims and presentation. Standard reference texts list it as a naturally occurring nitrogenous organic acid rather than a vitamin or mineral.
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.
Drotrecogin alfa (activated) (Xigris, marketed by Eli Lilly and Company) is a recombinant form of human activated protein C that has anti-thrombotic, anti-inflammatory, and profibrinolytic properties. Drotrecogin alpha (activated) belongs to the class of serine proteases. Drotrecogin alfa has not been found to improve outcomes in people with severe sepsis. The manufacturer's aggressive strategies in marketing its use in severe sepsis have been criticized. On October 25, 2011, Eli Lilly & Co. withdrew Xigris from the market after a major study showed no efficacy for the treatment of sepsis.
=== Pharmacokinetics === Peak plasma concentrations are seen two to three hours after oral dosing when fasting. Dofetilide is well absorbed in its oral form, with a bioavailability of >90%. Intravenous administration of dofetilide is not available in the United States. The elimination half-life of dofetilide is roughly 10 hours; however, this varies based on many physiologic factors (most significantly creatinine clearance), and ranges from 4.8 to 13.5 hours. Due to the significant level of renal elimination (80% unchanged, 20% metabolites), the dose of dofetilide must be adjusted to prevent toxicity due to impaired renal function. Dofetilide is metabolized predominantly by CYP3A4 enzymes predominantly in the liver and GI tract. This means that it is likely to interact with drugs that inhibit CYP3A4, such as erythromycin, clarithromycin, or ketoconazole, resulting in higher and potentially toxic levels of dofetilide.
The concept of Portal came from Narbacular Drop, a student project from the DigiPen Institute of Technology. The game included the aspects of placing portals on any flat surfaces and using them to maneuver around levels. Several Valve employees, attending a DigiPen career fair, saw Narbacular Drop and offered the entire team jobs at Valve almost immediately to help expand on their idea. Valve originally saw Portal as an experimental game to be included with its upcoming compilation, The Orange Box, alongside its release of Half-Life 2: Episode Two and Team Fortress 2. To give the game character, a minimal story, tied loosely with the Half-Life world, was written by Valve's Erik Wolpaw. He needed a character to guide the player through the game, coming onto a polite but humorous artificial intelligence, which would ultimately become the character of GLaDOS. Portal's release with The Orange Box received near-universal praise, with the standalone game earning an aggregate Metacritic rating of 90 out of 100. With success of the game, work on an expanded sequel began nearly immediately, expanding the development team from 8 to about 30-40 programmers. Initial ideas for Portal 2 retained the idea of solving puzzles through scientific concepts, but eliminating the use of portals altogether; these versions did not fare well with test audiences nor with Gabe Newell, Valve's president; these ideas were dropped though saved for potential reuse in a different game by Valve.
== Medical uses == Sitagliptin is used to treat type 2 diabetes. It is generally less preferred than metformin or sulfonylureas. It is taken by mouth. It is also available as the fixed-dose combinations of sitagliptin/metformin (Janumet, Janumet XR) and sitagliptin/simvastatin (Juvisync). Sitagliptin should not be used to treat type 1 diabetes. In December 2020, the US Food and Drug Administration (FDA) approved labeling changes stating that Januvia (sitagliptin), Janumet (sitagliptin and metformin hydrochloride), and Janumet XR (sitagliptin and metformin hydrochloride extended-release) are not proven to improve glycemic (blood sugar) control in children aged 10 to 17 with type 2 diabetes. The drugs are approved to improve blood sugar control in adults aged 18 and older with type 2 diabetes.
==== K ==== Kashk – is used in a large family of foods found in Lebanese, Palestinian, Egyptian, Kurdish, Iranian, and Central Asian cuisine. It is made from drained sour milk or yogurt by forming it and letting it dry. It can be made in a variety of forms, including rolled into balls, sliced into strips, and formed into chunks.
Sources: en.wikipedia.org
Extreme UV (EUV or sometimes XUV) is characterized by a transition in the physics of interaction with matter. Wavelengths longer than about 30 nm interact mainly with the outer valence electrons of atoms, while wavelengths shorter than that interact mainly with inner-shell electrons and nuclei. The long end of the EUV spectrum is set by a prominent He+ spectral line at 30.4 nm. EUV is strongly absorbed by most known materials, but synthesizing multilayer optics that reflect up to about 50% of EUV radiation at normal incidence is possible. This technology was pioneered by the NIXT and MSSTA sounding rockets in the 1990s, and it has been used to make telescopes for solar imaging. See also the Extreme Ultraviolet Explorer satellite.
Quadricyclane is abiotic, unreactive with biomolecules (due to complete saturation), relatively small, and highly strained (~80 kcal/mol). However, it is highly stable at room temperature and in aqueous conditions at physiological pH. It is selectively able to react with electron-poor π systems but not simple alkenes, alkynes, or cyclooctynes. Bis(dithiobenzil)nickel(II) was chosen as a reaction partner out of a candidate screen based on reactivity. To prevent light-induced reversion to norbornadiene, diethyldithiocarbamate is added to chelate the nickel in the product.
Many automated reticulocyte counts, like their manual counterparts, employ the use of a supravital dye such as new methylene blue to stain the red cells containing reticulin prior to counting. Some analysers have a modular slide maker which is able to both produce a blood film of consistent quality and stain the film, which is then reviewed by a medical laboratory professional.
== Relationship of GHRH and somatostatin == The actions of GHRH are opposed by somatostatin (growth-hormone-inhibiting hormone). Somatostatin is released from neurosecretory nerve terminals of periventricular somatostatin neurons, and is carried by the hypothalamo-hypophyseal portal circulation to the anterior pituitary where it inhibits GH secretion. Somatostatin and GHRH are secreted in alternation, giving rise to the markedly pulsatile secretion of GH.
Sources: en.wikipedia.org
On 20 August 2020, Russian opposition leader Alexei Navalny fell ill during a flight from Tomsk to Moscow. The plane made an emergency landing in Omsk, where Navalny was hospitalized and put in a medically induced coma. His family suspected his illness was caused by a poison put into a cup of tea he drank before the flight. He was evacuated to the Charité hospital in Berlin, Germany, the following day. On 2 September, the German government said that it had "unequivocal evidence" that Navalny was poisoned by a Novichok agent after tests at a German military lab and had called on the Russian government for an explanation, with labs in France and Sweden corroborating the findings. On 4 September, the North Atlantic Council was briefed by the German representative on the "appalling assassination attempt on" Navalny. In a post-meeting press conference, Secretary-General Jens Stoltenberg said that NATO allies "agree that Russia has serious questions it must answer", that the OPCW needed to conduct an impartial investigation, that "those responsible for this attack must be brought to justice" and called on Russia to "provide complete disclosure of the Novichok programme to the OPCW." Navalny had been out of his coma since 7 September. On 6 October, the OPCW confirmed the presence of a cholinesterase inhibitor from the Novichok group in Navalny's blood and urine samples. At the same time, the OPCW report clarified that Navalny was poisoned with a new type of Novichok, which was not included in the list of controlled chemicals of the Chemical Weapons Convention.
The two substrates of this enzyme are L-histidinol and oxidised nicotinamide adenine dinucleotide (NAD+). Its products are L-histidine, reduced NADH, and two protons. This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-OH group of donor with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is L-histidinol:NAD+ oxidoreductase. This enzyme is also called L-histidinol dehydrogenase.
=== Ornamental uses === Rhodium finds use in jewelry and for decorations. It is electroplated on white gold and platinum to give it a reflective white surface at time of sale, after which the thin layer wears away with use. This is known as rhodium flashing in the jewelry business. It may also be used in coating sterling silver to protect against tarnish (silver sulfide, Ag2S, produced from atmospheric hydrogen sulfide, H2S). Solid (pure) rhodium jewelry is very rare, more because of the difficulty of fabrication (high melting point and poor malleability) than because of the high price. The high cost ensures that rhodium is typically applied as an electroplate. Rhodium has also been used for honors or to signify elite status, when more commonly used metals such as silver, gold or platinum were deemed insufficient. In 1979 the Guinness Book of World Records gave Paul McCartney a rhodium-plated disc for being history's all-time best-selling songwriter and recording artist and in 2008, Barack Obama gave his wife a rhodium ring.
American gooseberry mildew and powdery mildew can infect the leaves and shoot tips, and botrytis may cause the fruit to rot in a wet season. Currant and gooseberry leaf spot (Drepanopeziza ribis) is another disease of blackcurrants, but it is not usually a serious problem as most cultivars now have some resistance. The blackcurrant leaf midge can cause browning, crimping and distortion of leaves at the tips of shoots but it is seldom a serious problem. The blackcurrant sawfly (Nematus ribesii) lays its eggs on the underside of the leaves and the voracious larvae work their way along the shoots, stripping off leaf after leaf. In a serious attack, the bush can be denuded of leaves. Larvae of the currant borer drill their way along the centres of shoots, which wilt and die back. Other insect pests include scale insects, aphids and earwigs.
=== Reversing the mechanism === The antioxidant N-acetyl-L-cysteine (NAC) is known to significantly reduce the cytotoxicity induced by DCBQ. NAC is a precursor of sulfhydryl-containing tripeptide glutathione (GSH), which is produced and kept at high levels in all cells, helping them defend against oxidative stress. Once NAC is inside the cell, it is rapidly hydrolyzed to cysteine so that it can be used to form GSH. Restoring the high GSH levels in the cell. NAC is available in oral, inhalation, and intravenous (IV) formulations.
Sources: en.wikipedia.org
Creatine is the base compound, while creatine monohydrate includes one water molecule per creatine molecule in its crystal structure. The monohydrate form is common in supplements and analytical standards. The body uses creatine itself after the water is removed or dissociated.
Yes. Meat, fish, and other animal tissues contain creatine. Cooking can convert some creatine to creatinine, which has no role in phosphocreatine energy buffering. Plant foods contain little or no creatine.
Creatinine is a cyclic breakdown product formed from creatine and phosphocreatine. It is filtered by the kidneys and commonly measured in blood and urine as a marker of renal function. Creatine monohydrate is a supplement ingredient and research chemical, not the same molecule.
Creatine monohydrate is the hydrated solid form of creatine, a nitrogen-containing compound involved in cellular energy metabolism. It consists of one creatine molecule associated with one water molecule in a crystal lattice.