The short version of HPLC fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2026-04-15. Anything still debated is marked as such rather than presented as settled.
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.
Quality control for creatine monohydrate typically combines identity, assay, and impurity tests. High-performance liquid chromatography with ultraviolet detection is common for separating creatine from creatinine and related substances. Nuclear magnetic resonance and infrared spectroscopy can confirm molecular structure, while titration may assess acid-base content. Moisture content, heavy metals, residual solvents, and microbial limits are checked according to applicable standards. These tests help distinguish compliant material from powders that have degraded, been diluted, or contain manufacturing residues.
Handling practices aim to limit moisture uptake and thermal exposure. Containers should stay closed when not in use, and storage areas should avoid direct sunlight, strong heat, and high humidity. Caking can occur when powder absorbs water, even if the creatine itself has not fully degraded. Aqueous stock solutions are best prepared fresh when needed because they are less stable than the solid. Open questions include how different excipients, packaging materials, and climate conditions affect long-term stability across global supply chains.
| Property | Value | Notes |
|---|---|---|
| Typical storage temperature | 15–25 °C | Protect from moisture, heat, and direct sunlight |
| Analytical method | HPLC with UV or RI detection | Separates creatine from creatinine and related impurities |
| Water content | About 12.1% w/w | Theoretical value for the monohydrate crystal |
| Degradation product | Creatinine | Formed by cyclization, especially in aqueous solution |
| Common assay specification | 98.0–102.0% | Range depends on the testing method and monograph |
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.
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.
Storage recommendations generally emphasize a cool, dry place away from direct sunlight and strong oxidizers. Sealed containers limit humidity exchange, which helps prevent clumping and gradual conversion to creatinine. Long-term stability studies usually monitor appearance, moisture, and purity at intervals under defined temperature and humidity conditions. Accelerated tests at elevated temperature can reveal degradation pathways, but they do not perfectly predict room-temperature shelf life. Questions remain about how much creatinine formation is acceptable in different product categories and how packaging choices affect that rate over time.
Commercial creatine monohydrate is typically manufactured through chemical synthesis, often starting from sarcosine and cyanamide. The resulting material is crystallized, washed, and dried to a specified hydrate content. Finished lots are tested for identity, purity, moisture, and heavy metals before release. Because the compound can cyclize to creatinine under heat or prolonged storage in solution, manufacturers control temperature and humidity during processing. The solid itself is relatively stable when kept dry and sealed, but moisture uptake can cause caking and complicate accurate assay.
=== Safety aspects === Processing of nanocellulose does not cause significant exposure to fine particles during friction grinding or spray drying. No evidence of inflammatory effects or cytotoxicity on mouse or human macrophages can be observed after exposure to nanocellulose. The results of toxicity studies suggest that nanocellulose is not cytotoxic and does not cause any effects on inflammatory system in macrophages. In addition, nanocellulose is not acutely toxic to Vibrio fischeri in environmentally relevant concentrations. Despite intensified research on oral food or pharmaceutical formulations containing nanocelluloses they are not generally recognized as safe. Nanocelluloses were demonstrated to exhibit limited toxicity and oxidative stress in in vitro intestinal epithelium or animal models.
The Aleutian Islands ( ə-LOO-shən or ə-LEW-shən), also called the Aleut Islands, or Aleutic Islands, are a chain of 14 main, larger volcanic islands and 55 smaller ones. Most of the islands belong to the U.S. state of Alaska, with the archipelago encompassing the Aleutians West Census Area and the Aleutians East Borough. The Commander Islands, located farther to the west, belong to the Russian federal subject of Kamchatka Krai, of the Russian Far East. The islands form part of the Aleutian Arc of the Northern Pacific Ocean, and occupy a land area of 6,821 sq mi (17,666 km2) that extends westward roughly 1,200 mi (1,900 km) from the Alaska Peninsula mainland, in the direction of the Kamchatka Peninsula; the archipelago acts as a border between the Bering Sea to the north and the Pacific Ocean to the south. Crossing longitude 180°, at which point east and west longitude end, the archipelago contains both the westernmost and easternmost parts of the United States, by longitude (Amatignak Island and Semisopochnoi Island, respectively). The westernmost U.S. island, in real terms, however, is Attu Island, west of which runs the International Date Line. The islands, with their 57 volcanoes, form the northernmost part of the Pacific Ring of Fire. Physiographically, they are a distinct section of the larger Pacific Border province, which, in turn, is part of the larger Pacific Mountain System physiographic division. The islands are considered to be among the most geographically isolated areas of the Northern Pacific.
Indigenous allies were crucial to conquest, as well as to creating and maintaining empire. Indigenous peoples in Colombia experienced a decline in population due to conquest as well as Eurasian diseases, such as smallpox, to which they had no immunity. Regarding the land as deserted, the Spanish Crown sold properties to all persons interested in colonized territories, creating large farms and possession of mines. In the 16th century, the nautical science in Spain reached a great development thanks to numerous scientific figures of the Casa de Contratación and nautical science was an essential pillar of the Iberian expansion. In 1542, the region of New Granada, along with all other Spanish possessions in South America, became part of the Viceroyalty of Peru, with its capital in Lima. In 1547, New Granada became a separate captaincy-general within the viceroyalty, with its capital at Santa Fe de Bogota. In 1549, the Royal Audiencia was created by a royal decree, and New Granada was ruled by the Royal Audience of Santa Fe de Bogotá, which at that time comprised the provinces of Santa Marta, Rio de San Juan, Popayán, Guayana and Cartagena. But important decisions were taken from the colony to Spain by the Council of the Indies.
==== Surfactins ==== As the name implies, surfactins are potent biosurfactants (surfactants produced by bacteria, yeast, or fungi), and they have been shown to reduce the surface tension of water from 72 to 27 mN/m at very low concentrations. Furthermore, surfactins are also able to permeabilize lipid membranes, allowing them to have specific antimicrobial and antiviral activities. Since surfactins are biosurfactants, they have diverse functional properties. These include low toxicity, biodegradability and a higher tolerance towards variation of temperature and pH, making them very interesting for use in a wide range of applications.
Sources: en.wikipedia.org
Hyōjun (標準): standard grade, contains more than 1.2% total nitrogen Jōkyū (上級): upper grade, contains more than 1.35% of total nitrogen Tokkyū (特級): special grade, contains more than 1.5% of total nitrogen
When purifying proteins, alkalies such as sodium hydroxide (NaOH) can be used safely and effectively. It is also widely used for depyrogenation of non-autoclavable equipment (e.g. plastics) and chromatography columns. In fact, when using an anion exchanger to remove pyrogens, it is necessary to clean the column with NaOH after each batch.
In preparation for the 1998 finals series, and despite losing six of their last eight to the Roos, legendary Essendon coach Kevin Sheedy publicly labelled North executives Greg Miller and Mark Dawson soft in response to comments from commentators that his Essendon team was soft. The Kangaroos beat Essendon in the much-hyped encounter that followed (a Qualifying Final), and North fans pelted Sheedy with marshmallows as he left the ground, although Sheedy was seemingly unfazed by the incident, encouraging a "Marshmallow Game" the next year and relishing in the fact that Sheedy's ulterior motive was to build up the game and draw a large crowd, which proved to be correct, drawing in 71,154 people to attend the game. In 2000, the Bombers thrashed North by 125 points in the 1st Qualifying Final. The biggest VFL/AFL comeback of all time occurred between the two teams when Essendon managed to come back from a 69-point deficit to win by 12 points in 2001. A meeting of the two rivals at the MCG in the 2014 AFL finals series in the 2nd Elimination Final resulted in North winning by 12 points. West Coast – A three-decade rivalry between the Essendon Bombers and the West Coast Eagles kicked off when Essendon coach Kevin Sheedy tied the windsock down on the School End outer terrace so the opposition would not know which way the wind was blowing. Sheedy later said of the incident three decades later, in jest, that it was because the brand sponsor had neglected to pay their account. When West Coast won the toss and kicked against the breeze, it looked as if Sheedy's plan had worked.
=== Preservatives and Antioxidants === Oils and fats used in topical cream formulations are susceptible to oxidation by atmospheric oxygen or microorganism action. The stability against oxidation can be enhanced by the introduction of antioxidants. The selection of antioxidants and their concentration can only be determined by testing their effectiveness on the final product, according to pharmacopoeial information. The efficiency of antioxidants depends on their compatibility with other excipients and oil/water partition coefficient. Oxidations from microbiological source influence the physicochemical properties of the emulsion, resulting in color and odor changes, fat and oil hydrolysis, pH changes in the aqueous phase, or phase separation of the cream. Oil-in-water creams are more susceptible to microbial contamination. Therefore, preservatives are included to prevent any microorganism growth. Preservatives suitable for topical cream formulations must present a broad spectrum of bactericidal activity, low logP, compatibility with other excipients, stability, and effectiveness over a wide range of pH and temperatures.
==== Stable isotope labeling with amino acids in cell culture ==== Stable isotope labeling with amino acids in cell culture (SILAC) is a method that involves metabolic incorporation of "heavy" C- or N-labeled amino acids into proteins followed by MS analysis. SILAC requires growing cells in specialized media supplemented with light or heavy forms of essential amino acids, lysine or arginine. One cell population is grown in media containing light amino acids while the experimental condition is grown in the presence of heavy amino acids. The heavy and light amino acids are incorporated into proteins through cellular protein synthesis. Following cell lysis, equal amounts of protein from both conditions are combined and subjected to proteotypic digestion. Arginine and lysine amino acids were chosen, because trypsin, the predominant enzyme used to generate proteotypic peptides for MS analysis, cleaves at the C-terminus of lysine and arginine. Following digestion with trypsin, all the tryptic peptides from cells grown in SILAC media would have at least one labeled amino acid, resulting in a constant mass shift from the labeled sample over non-labeled. Because the peptides containing heavy and light amino acids are chemically identical, they co-elute during reverse-phase column fractionation and are detected simultaneously during MS analysis. The relative protein abundance is determined by the relative peak intensities of the isotopically distinct peptides. Traditionally the level of multiplexing in SILAC was limited due to the number of SILAC isotopes available.
Sources: en.wikipedia.org
=== Redox indicator === Methylene blue is widely used as a redox indicator in analytical chemistry. Solutions of this substance are blue when in an oxidizing environment, but will turn colorless if exposed to a reducing agent.
== Myths == A common myth among radar and microwave communication workers is that the exposure of the genital area to microwaves renders a man sterile for about a day. The power density necessary for this effect is however sufficient to also cause permanent damage.
Scottish Labour suspends Wilma Brown, its parliamentary candidate for Cowdenbeath and Kirkcaldy, following reports she liked racist and Islamophobic posts on social media. 11 April – The Department for Science, Innovation and Technology says that the legal fees for Michelle Donelan came to over £19,000. Sally Bunce, the Green Party candidate for Mayor of the Tees Valley in the May election, drops out of the contest saying she does not want to split the vote against the Conservative candidate. Reform UK apologise to the family of their dropped candidate for York Central Tommy Cawkwell for "inactivity" not knowing that he had died. Joe Haines and Lord Donoughue, who were two of Harold Wilson's advisers during his time as prime minister, tell The Times that Wilson had an affair with his deputy press secretary, Janet Hewlett-Davies, during the 1970s. Mid and East Antrim Borough Council is refused permission to rename its town hall complex after the late Queen Elizabeth II. 12 April – Greater Manchester Police launch an investigation into Labour's deputy leader, Angela Rayner, over the sale of her council house amid allegations she broke electoral law by giving false information about her place of residence. Rayner pledges to step down if she is found guilty of any crime. Keir Starmer says that if elected to government, Labour will raise defence spending to 2.5% of GDP. He also makes an "unshakable" commitment to nuclear weapons.
== Function == The immune system must be able to discriminate between self and non-self. When self/non-self discrimination fails, the immune system destroys cells and tissues of the body and as a result causes autoimmune diseases. Regulatory T cells actively suppress activation of the immune system and prevent pathological self-reactivity, i.e. autoimmune disease. The critical role regulatory T cells play within the immune system is evidenced by the severe autoimmune syndrome that results from a genetic deficiency in regulatory T cells (IPEX syndrome – see also below).
The isotopes 192Ir and 60Co are preferred for radiography, since iridium and cobalt are chemically non-reactive metals and can be obtained with much higher specific activities by the activation of stable 191Ir and 59Co in high-flux reactors. However, while 137Cs is a waste product produced in great quantities in nuclear fission reactors, 192Ir and 60Co are specifically produced in commercial and research reactors and their life cycle entails the destruction of the involved high-value elements. Cobalt-60 decays to stable nickel, whereas iridium-192 can decay to either stable osmium or platinum. Due to the residual radioactivity and legal hurdles, the resulting material is not commonly recovered even from "spent" radioactive sources, meaning in essence that the entire mass is "lost" for non-radioactive uses. As an almost purely synthetic isotope not existing in the environment before 1945, caesium-137 has been used to date wine and detect counterfeits and as a relative-dating material for assessing the age of sedimentation occurring after 1945. Caesium-137 is also used as a radioactive tracer in geologic research to measure soil erosion and deposition; its affinity for fine sediments is useful in this application.
Sources: en.wikipedia.org
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.
In solution, creatine can cyclize spontaneously to creatinine. Heat and certain pH conditions increase the rate of this conversion. Dry crystalline material is more stable because the reaction requires water.
Typical storage is in a sealed container at room temperature, away from moisture and direct heat. These conditions reduce caking and slow degradation. Liquid products require more careful handling because creatine is less stable in water.
Keep it in a sealed container in a cool, dry place away from direct heat and moisture. Dry powder is more stable than prepared solutions.