If you have been reading about HPLC-UV 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 2025-08-19. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical formula | C4H9N3O2·H2O | Monohydrate; anhydrous base is C4H9N3O2 |
| Molar mass | 149.15 g/mol | Calculated for the monohydrate form |
| Appearance | White crystalline powder | Typical laboratory and food-grade material |
| Solubility in water | Sparingly soluble at room temperature | Solubility increases with temperature |
| Common synonyms | Methylguanidoacetic acid; N-(aminoiminomethyl)-N-methylglycine | Synonyms refer to the creatine base, not the hydrate specifically |
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.
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 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.
== Fuels and consumption == Ashing is a test to deduce the amount of ash forming material present in a petroleum product so as to decide its use in certain applications. Ash-forming materials are considered to be undesirable impurities or contaminants. In the ash analysis of petroleum products, ash content represents the incombustible component remaining after a sample of the furnace oil is completely burned. The ash content of petroleum products is generally low. It is defined as the inorganic residue that remains after combustion of the oil in air at specific high temperature. Ash typically ranges from 0.1 to 0.2% in oil. Some of the ash forming constituents occur naturally in crude oil; others are present as a result of refining or contamination during storage or distribution. Knowledge of the amount of ash-forming material present in a product can provide information as to whether or not the product is suitable application. In the ash analysis of coal and other solid fuels, the amount of sulfur retained in the ash during the ashing process is not constant, but rather is dependent upon the conditions of ashing as well as the other inorganic constituents in the ash that may form sulfates during the ashing procedure. As such, different ashing procedures may yield different ash contents.
=== Adulteration === Despite attempts at quality control and standardisation, an extensive history of saffron adulteration, particularly among the cheapest grades, continues into modern times. Adulteration was first documented in Europe's Middle Ages, when those found selling adulterated saffron in Nuremberg were executed under the Safranschou code. Typical methods include mixing in extraneous substances like beetroot, pomegranate fibres, red-dyed silk fibres, or the saffron crocus's tasteless and odourless yellow stamens. Other methods included dousing saffron fibres with viscid substances like honey or vegetable oil to increase their weight. Powdered saffron is more prone to adulteration, with turmeric, paprika, and other powders used as diluting fillers. Adulteration can also consist of selling mislabelled mixes of different saffron grades. Thus, high-grade Kashmiri saffron is often sold and mixed with cheaper Iranian imports; these mixes are then marketed as pure Kashmiri saffron. Safflower is a common substitute sometimes sold as saffron. The spice is reportedly counterfeited with horse hair, corn silk, or shredded paper. Tartrazine or sunset yellow dyes have been used to colour counterfeit powdered saffron. In recent years, saffron adulterated with the colouring extract of gardenia fruits has been detected in the European market. This form of fraud is difficult to detect due to the presence of flavonoids and crocines in the gardenia-extracts similar to those naturally occurring in saffron.
5 January The Metropolitan Police says it is not investigating allegations against Prince Andrew after unsealed court papers in the United States contained groping allegations against him. Critics brand comments by Sir Howard Davies, chair of NatWest, as "astounding" and "out of touch with reality" after he told BBC Radio 4's Today programme it was "not that difficult" for someone to buy a house. Chris Skidmore, MP for Kingswood, announces his intention to stand down from Parliament "as soon as possible" in protest at the UK government's decision to issue more oil and gas licences. His decision will trigger another by-election. Lawyers representing potential victims of the British Post Office scandal say they have been contacted by a further 50 people following the broadcast of the ITV drama Mr Bates vs The Post Office. 6 January The Metropolitan Police confirms it has launched an investigation into the Post Office for potential fraud over the Horizon IT scandal. The rate of National Insurance is reduced from 12% to 10%, reducing NI contributions for an estimated 27 million employees earning between £12,571 and £50,270. 7 January Sir Keir Starmer admits he worries about the toll of a general election year on his two teenage children as he and his wife try to keep them out of the public eye. Sunak describes the Post Office scandal as "an appalling miscarriage of justice" and says the government is looking at ways to clear the names of those convicted because of faulty IT software.
Sources: en.wikipedia.org
== Non-enzymatic transamination == A second type of transamination reaction can be described as a nucleophilic substitution of one amine or amide anion on an amine or ammonium salt. For example, the attack of a primary amine by a primary amide anion can be used to prepare secondary amines:
Ancient philosophers as far back as Thales of Miletus c. 550 BCE had inklings of the conservation of some underlying substance of which everything is made. However, there is no particular reason to identify their theories with what we know today as "mass-energy" (for example, Thales thought it was water). Empedocles (490–430 BCE) wrote that in his universal system, composed of four roots (earth, air, water, fire), "nothing comes to be or perishes"; instead, these elements suffer continual rearrangement. Epicurus (c. 350 BCE) on the other hand believed everything in the universe to be composed of indivisible units of matter—the ancient precursor to 'atoms'—and he too had some idea of the necessity of conservation, stating that "the sum total of things was always such as it is now, and such it will ever remain." In 1605, the Flemish scientist Simon Stevin was able to solve a number of problems in statics based on the principle that perpetual motion was impossible. In 1639, Galileo published his analysis of several situations—including the celebrated "interrupted pendulum"—which can be described (in modern language) as conservatively converting potential energy to kinetic energy and back again. Essentially, he pointed out that the height a moving body rises is equal to the height from which it falls, and used this observation to infer the idea of inertia. The remarkable aspect of this observation is that the height to which a moving body ascends on a frictionless surface does not depend on the shape of the surface.
The specific adaptive immune response regulated by the TH cell depends on its subtype (i.e., T-helper1, T-helper2, T-helper17, and regulatory T-cell), which is distinguished by the types of cytokines they secrete. Regulatory T cells are yet another distinct population of T cells that provide the critical mechanism of tolerance, whereby immune cells are able to distinguish invading cells from "self." This prevents immune cells from inappropriately reacting against one's own cells, known as an autoimmune response. For this reason, these regulatory T cells have also been called "suppressor" T cells. These same regulatory T cells can also be co-opted by cancer cells to prevent the recognition of, and an immune response against, tumor cells.
Sources: en.wikipedia.org
Spray lubricants may contain wax or PTFE. While these lubricants use tack additives to stay on the chain they can also attract dirt and sand from the road and over time produce a grinding paste that accelerates component wear. Oil drip feed systems continuously lubricate the chain and use light oil that does not stick to the chain. Research has shown that oil drip feed systems provide the greatest wear protection and greatest power saving.
=== Characterization === Cox described Logan Roy as a "mysterious character in many ways. I have a lot of empathy for him. I think he's very misunderstood. I think he's a tragic figure", and compared him to Shakespeare's tragic kings, such as Henry IV. "Obviously there's Lear connotations, but it's also the father dealing with a child in his son Hal and not understanding him." David Rasche, who plays Karl Muller, suggested to Jesse Armstrong that his character became a confessor to Logan, "But I don't think Jesse wanted that. Jesse wanted Logan Roy, a man alone." Cox thinks of Logan as "quite Puritan [...] Logan's a bastard, but he's not an indecent bastard." On Logan's romantic relationships he has said "He clearly loves Marcia. There's this idea that he had this affair with Rhea, but I'm not sure that happened. Both Holly [Hunter] and I felt that hadn't actually happened, [...] The kids thinking they were having an affair was more them projecting", but also added that "he's not good at relationships at all. The female relationships in his life have been pretty disastrous". By the final season Cox noted that, Colin and Kerry, Logan's bodyguard and assistant respectively, were "the two people who matter to him most." Cox has expressed that he believes that Logan's greatest weakness was that "he loves his children desperately." In interviews with The New Yorker, Armstrong agreed with Cox that Logan loves his children, even if he had done "things which are antithetical to what most people would consider to be love."
=== Clinical phase unknown === Sildenafil orally-dissolving film (NAL8238; NAL-8238; sildenafil ODF) – phosphodiesterase PDE5 inhibitor – erectile dysfunction [34] Tadalafil orally-dissolving film (NAL8233; NAL-8233; tadalafil ODF) – phosphodiesterase PDE5 inhibitor – erectile dysfunction [35]
Sources: en.wikipedia.org
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.
No. Creatinine is a breakdown product formed when creatine loses water and cyclizes, and it is not the same compound. The two names are similar but refer to different chemical structures and roles.
The body synthesizes creatine from amino acids, mainly in the liver and kidneys. It also comes from animal foods such as meat and fish, while plant foods contain little or none.
Purity testing often uses high-performance liquid chromatography to measure creatine and creatinine. Water content can be checked by Karl Fischer titration. Additional tests may cover heavy metals, residual solvents, and microbial contamination.