If you have been reading about HPLC assay 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 2026-03-11. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
In the body, creatine is synthesized from arginine, glycine, and methionine, mainly in the liver and kidneys, and is also obtained from foods such as meat and fish. About 95% of body creatine is stored in skeletal muscle, where a fraction is phosphorylated to phosphocreatine. Phosphocreatine serves as a rapid reserve of high-energy phosphate for short bursts of ATP regeneration. The monohydrate form supplies creatine after dissolution and absorption, but it is not itself the active phosphorylated species.
In aqueous solution, creatine monohydrate undergoes a slow conversion to creatinine, a cyclized degradation product. This reaction is pH- and temperature-dependent, and it proceeds faster in warm or alkaline conditions. Because the conversion is gradual, analytical measurements of creatine in solution must account for time and storage history. The equilibrium favors creatinine more strongly at higher temperatures, which is relevant to sample handling in laboratories and to beverage formulations. Refrigeration slows but does not entirely stop this process.
Quality assessment of creatine monohydrate typically uses high-performance liquid chromatography to separate creatine from creatinine and other impurities. Other methods include nuclear magnetic resonance spectroscopy, titration, and infrared spectroscopy for identity confirmation. Purity is often reported as a percentage of the labeled compound on a dry basis, while moisture content is measured separately. Because different analytical methods have different selectivity, comparing purity values across sources requires attention to the method and sample preparation.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C4H9N3O2·H2O | Creatine plus one water molecule in the crystal lattice. |
| Molar mass | 149.15 g/mol | Calculated for the monohydrate form. |
| Appearance | White crystalline powder | Typical solid form; particle size can vary by processing. |
| Solubility class | Sparingly soluble in water | Dissolution improves with time, stirring, and temperature. |
| Common synonyms | Creatine hydrate; N-carbamimidoyl-N-methylglycine monohydrate | Names vary by chemical registry and supplier. |
Researchers at Bristol-Myers Squibb found that increased steric bulk of the N-terminal amino acid side-chain led to increased stability. To additionally increase stability the trans-rotamer was stabilized with a cis-4,5-methano substitution of the pyrrolidine ring, resulting in an intramolecular van-der-Waals interaction, thus preventing intramolecular cyclisation. Because of that increased stability, the researchers continued their investigation on cis-4,5-methano cyanopyrrolidines and came across with a new adamantyl derivative, which showed extraordinary ex vivo DPP-4 inhibition in rat plasma. Also noted, high microsomal turnover rate which indicated that the derivative was quickly converted to an active metabolite. After hydroxylation on the adamantyl group they had a product with better microsomal stability and improved chemical stability. That product was named saxagliptin (Onglyza) (Figure 6). In June 2008 AstraZeneca and Bristol-Myers Squibb submitted a new drug application for Onglyza in the United States and a marketing authorization application in Europe. Approval was granted in the United States by the FDA in July 2009 for Onglyza 5 mg and Onglyza 2.5 mg. This was later combined with extended-release metformin (taken once daily) and approved by the FDA in January 2011 under the trade name Kombiglyze XR.
Although most applications focus on the detection of positive ions, measurements in the negative mode are for most of the plasma-based ion sources also possible. In this case, reagent ions, such as O2–, can deprotonate the analyte molecules to give [M–H]– quasimolecular ions, or form adducts with species such as NO3–, yielding [M+NO3]– ions. Measurements in the negative ion mode are especially favorable when the analyte molecules exhibit a high gas-phase acidity, as is the case for carboxylic acids. One of the most used plasma-based techniques for ambient ionization is probably direct analysis in real time (DART), since it is commercially available. DART is an atmospheric pressure ion source that operates by exposing the sample to a gas stream (typically helium or nitrogen) that contains long-lived electronically or excited neutral atoms, vibronically excited molecules (or "metastables"). Excited states are formed in a glow discharge in a chamber through which the gas flows.
=== Awards === Half-Life: Alyx won "Game of the Year" at the 2020 VR Awards. At the Game Awards 2020, it was nominated for "Best Game Direction", "Best Audio Design" and "Best Action", and won for "Best VR/AR". At the 17th British Academy Games Awards, it was nominated for "Best Game", "Game Direction", "Audio Achievement" and "Artistic Achievement". At the 24th Annual D.I.C.E. Awards, it was nominated for "Action Game of the Year", "Outstanding Achievement in Game Direction", and "Outstanding Achievement in Game Design", and won for "Immersive Reality Technical Achievement" and "Immersive Reality Game of the Year".
Aspirin: may increase valproate concentrations. May also interfere with valproate's metabolism. Benzodiazepines: may cause CNS depression and there are possible pharmacokinetic interactions. Carbapenem antibiotics: reduce valproate levels, potentially leading to seizures. Cimetidine: inhibits valproate's metabolism in the liver, leading to increased valproate concentrations. Erythromycin: inhibits valproate's metabolism in the liver, leading to increased valproate concentrations. Ethosuximide: valproate may increase ethosuximide concentrations and lead to toxicity. Felbamate: may increase plasma concentrations of valproate. Mefloquine: may increase valproate metabolism combined with the direct epileptogenic effects of mefloquine. Oral contraceptives: may reduce plasma concentrations of valproate. Primidone: may accelerate metabolism of valproate, leading to a decline of serum levels and potential breakthrough seizure. Rifampicin: increases the clearance of valproate, leading to decreased valproate concentrations. Warfarin: valproate may increase free warfarin concentration and prolong bleeding time. Zidovudine: valproate may increase zidovudine serum concentration and lead to toxicity.
Sources: en.wikipedia.org
== Effects of the Closure == Madera Community Hospital was the only hospital within a 30 mile radius, thus the closure caused 160,000 Madera residents to not have access to a local emergency room. Many people were faced with driving the 45 minutes to one of the neighboring towns or not receiving proper treatment. Unfortunately, this decision was already made for residents without access to a vehicle or public transportation. Other hospitals in the Central Valley were then stressed by the pressures of taking on all of the patients who would have previously been treated in Madera, which caused significant increases in emergency room wait times. Private ambulance companies from other counties pitched in to help take calls from Madera to transport residents to other hospitals such as Saint Agnes Medical Care (Fresno) and Community Regional Medical Center (Fresno). Not only were the patients redirected, 772 employees across the four locations were laid off when the hospital shuttered its doors.
PEGylation as a method to improve half-life has been successfully demonstrated many times; in one example it shows that site specific mono-PEGylation of GLP-1 led to a 16-fold increase in plasma half-life time in rats. On the other hand, covalently attaching PEG can often lead to loss of biological activity. Another chemical modification is the attachment of glycosyl (carbohydrate) units to the peptide to help with peptide delivery to target sites. The introduction of carbohydrates to peptides can alter the physiological properties, to improve bioavailability. Advantages of this technique include increased metabolic stability, and facilitated transport across cell membranes, although of the most favourable aspects is their ability to promote oral absorption. Peptides have a very low oral availability (less than 1–2%), as a result of insufficient absorption and rapid degradation and clearance, thus making this method an attractive one. N- and O-glycosylation in which carbohydrates are attached to the peptide are naturally occurring, where N-glycosylation occurs through the amine group of an asparagine residue to form an amide bond. O-glycosylation occurs via serine or threonine residues, where the oxygen atom on the side chain binds to the carbohydrate through an ether bond. There is also non-natural glycosylation, known as chemical glycosylation, which involves the attachment of carbohydrate units to different amino acid residues at the N-terminus of the peptide's sequence.
The Gin Craze was a period in the first half of the 18th century when the consumption of gin increased rapidly in Great Britain, especially in London. By 1743, The average English person was drinking 2.2 gallons (10 litres) of gin per year. The Sale of Spirits Act 1750 (commonly known as the Gin Act 1751) was an Act of the Parliament of Great Britain (24 Geo. 2. c. 40) which was enacted to reduce the consumption of gin and other distilled spirits, a popular pastime that was regarded as one of the primary causes of crime in London.
=== Peptide masking === Similar to the idea of pro-drugs, another way of masking the drugs chemical composition is by masking a peptide's characteristics by combining with other molecular groups that are more likely to pass through the blood–brain barrier. An example of this is using a cholesteryl molecule instead of cholesterol that serves to conceal the water soluble characteristics of the drug. This type of masking as well as aiding in traversing the blood–brain barrier. It also can work to mask the drug peptide from peptide-degrading enzymes in the brain Also a "targetor" molecule could be attached to the drug that helps it pass through the barrier and then once inside the brain, is degraded in such a way that the drug cannot pass back through the brain. Once the drug cannot pass back through the barrier the drug can be concentrated and made effective for therapeutic use. However drawbacks to this exist as well. Once the drug is in the brain there is a point where it needs to be degraded to prevent overdose to the brain tissue. Also if the drug cannot pass back through the blood–brain barrier, it compounds the issues of dosage and intense monitoring would be required. For this to be effective there must be a mechanism for the removal of the active form of the drug from the brain tissue.
===== Divestments ===== On October 21, 2011, Par Pharmaceutical has sealed the deal to three products from Teva Pharmaceutical Industries, which the Israeli firm was required by the US Federal Trade Commission to divest before it could acquire US biotech Cephalon for $6.8 billion. Following the acquisition of Allergan plc generic division some assets have been sold off to meet US antitrust requirements. In June 2016 Indian pharmaceutical company Dr. Reddy's Laboratories Ltd bought 8 (ANDA) Abbreviated New Drug Applications for $350 million in cash. Also in June 2016 Teva sold two ANDAs to Indian pharmaceutical company Zydus Cadilla, strengthening its US portfolio. On June 21, 2016, American pharmaceutical company Amneal Pharmaceutical previously known as Impax Laboratories bought a portfolio of generic drugs from Teva Pharmaceutical Industries for about $586 million. On July 29, Cipla an Indian pharmaceutical company bought three products from Teva. Indian pharmaceutical company, Aurobindo, was in the race to buy some Teva assets. In October 2016, Teva has sold off part of its UK and Ireland generic business to Indian pharmaceutical company Intas Pharma for 600 million pounds (5083 crore Indian rupees) in cash. In August 2016, Australia pharmaceutical company Mayne Pharmaceutical bought a portfolio of drugs from pharmaceutical giant Teva Pharmaceuticals last year for $845 million Australian dollars.
Sources: en.wikipedia.org
=== Taste === People who can taste phenylthiocarbamide (PTC), which is either bitter or tasteless, are less likely to find cruciferous vegetables palatable due to the resemblance between isothiocyanates and PTC.
On May 20, 2025, U.S. president Donald Trump announced plans for a new space-based missile defense system called the "Golden Dome" intended to shield the United States from long-range and hypersonic missiles. The name alludes to Israel's Iron Dome but the system is planned to be orders of magnitude broader in scope. Technical details and deployment plans were not released. Trump said the project would be completed within three years and cost about $175 billion, a feasibility, timeline, and price estimate that were quickly and widely disputed. The Congressional Budget Office estimated that it could cost between $161 billion and $542 billion over 20 years, while Republican senators involved in the program predicted it would ultimately cost "trillions of dollars." In April 2025 the Director, Operational Test and Evaluation (DOT&E) determined that the Golden Dome fell under its oversight, as they are required by law to analyze testing plans for defense programs with procurements above $3 billion. Days later, Elon Musk's Department of Government Efficiency (DOGE) investigated the office and slashed its resources. A defense official told CNN that they believed DOGE wanted to prevent DOT&E conducting independent oversight of the Golden Dome. In May 2025, 42 members of US Congress formally asked the DoD Inspector General to review Elon Musk’s involvement in the Golden Dome.
Chemist Gary Molander of the University of Pennsylvania described how "[d]ozens of biotechnology and drug companies were started" based on Hirschmann's developments and that "[t]he whole biotechnology field" and new classes of medicines, such as protease inhibitors for the treatment of AIDS, were established through his approach. As head of Merck's department of new lead discovery starting in 1971 and as senior vice president for basic research in chemistry starting in 1978, serving until the retirement age of 65, when he left the firm in 1987, Hirschmann played a pivotal role in the development of many of the firm's products. Among the medications he was involved with was the development of the antiparasitic Ivermectin used for the treatment of river blindness, the statin Mevacor for reducing cholesterol in patients at risk of cardiovascular disease, the beta-lactam-family broad-spectrum antibiotic Primaxin, the synthetic androgen Proscar used for the treatment of enlarged prostate and prostate cancer and of the ACE inhibitor Vasotec for treating hypertension. Following his departure from Merck, Hirschmann taught at the University of Pennsylvania and the Medical University of South Carolina until his retirement in 2006.
While medical treatment may help with the initial symptoms of opioid withdrawal, once the first stages of withdrawal are through, a method for long-term preventive care is attendance at 12-step groups such as Narcotics Anonymous (NA). NA's 12-step process is based on the 12-step facilitation of Alcoholic Anonymous (AA) and centers on peer support, self-help, and spiritual connectedness. Some evidence also supports the use of these programs for adolescents. Multiple studies have shown increased abstinence for those in NA compared to those who are not. Members report a median abstinence length of 5 years.
=== Developments in production === Until the end of the 19th century, vaccination was performed either directly with vaccine produced on the skin of calves or, particularly in England, with vaccine obtained from the calf but then maintained by arm-to-arm transfer; initially in both cases vaccine could be dried on ivory points for short-term storage or transport but increasing use was made of glass capillary tubes for this purpose towards the end of the century. During this period there were no adequate methods for assessing the safety of the vaccine and there were instances of contaminated vaccine transmitting infections such as erysipelas, tetanus, septicaemia and tuberculosis. In the case of arm-to-arm transfer there was also the risk of transmitting syphilis. Although this did occur occasionally, estimated as 750 cases in 100 million vaccinations, some critics of vaccination e.g. Charles Creighton believed that uncontaminated vaccine itself was a cause of syphilis. Smallpox vaccine was the only vaccine available during this period, and so the determined opposition to it initiated a number of vaccine controversies that spread to other vaccines and into the 21st century. Sydney Arthur Monckton Copeman, an English Government bacteriologist interested in smallpox vaccine, investigated the effects on the bacteria in it of various treatments, including glycerine. Glycerine was sometimes used simply as a diluent by some continental vaccine producers.
Sources: en.wikipedia.org
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.
Meat and fish contain creatine, and the human body also synthesizes it from amino acids. The monohydrate form is not a natural food ingredient as such; it is a manufactured crystalline solid that provides creatine after ingestion. Food sources contribute to total body creatine stores alongside endogenous synthesis.
It means the crystal lattice includes one molecule of water for each molecule of creatine. This water is part of the solid's ordered structure, not bulk moisture. The hydrate form influences properties such as solubility, density, and shelf stability.
Dry, sealed creatine monohydrate can remain stable for years, but storage conditions affect its shelf life. Moisture, heat, and repeated opening of containers can reduce quality over time.