A practical reference on HPLC: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2026-05-19. Anything still debated is marked as such rather than presented as settled.
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.
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.
Identity and purity are assessed with several complementary methods. High-performance liquid chromatography can separate creatine from creatinine and related impurities, often with ultraviolet detection. Nuclear magnetic resonance and infrared spectroscopy provide structural confirmation, while Karl Fischer titration measures water content. Elemental analysis and mass spectrometry may be used for additional confirmation, especially in research or forensic settings. No single method captures every quality attribute, so laboratories typically combine results and compare them against a specification.
Creatine monohydrate is sold as a dietary ingredient in some countries and as a food supplement in others. Regulatory frameworks vary, so purity limits, labeling rules, and permitted claims are not globally uniform. In the United States, it falls under dietary supplement rules, whereas the European Union treats it as a food supplement ingredient. Pharmacopeial monographs, where they exist, can provide public quality standards, but not every product is required to meet them. Questions about long-term effects and patterns of use remain areas of active study rather than settled regulatory findings.
Solid creatine monohydrate is generally stable when kept cool and dry, but it can hydrolyze to creatinine over time. Moisture, heat, and acidic conditions accelerate this conversion, which reduces assay values and changes the material's properties. Creatinine is a cyclic dehydration product that is also a normal human metabolite, so its presence in a sample is not necessarily a health concern by itself. In quality testing, creatinine is monitored as a marker of degradation and purity.
| 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. |
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.
Analytical laboratories commonly identify creatine monohydrate by high-performance liquid chromatography with ultraviolet detection, often after dissolving the sample in water or dilute acid. Ion-exchange or reversed-phase columns separate creatine from creatinine and related guanidino compounds. Nitrogen content can be checked by Kjeldahl or combustion methods, while moisture is measured by Karl Fischer titration or loss on drying. These techniques give complementary views: chromatographic purity addresses related substances, whereas moisture and elemental data confirm hydrate stoichiometry. No single test defines quality by itself; a combination is used in specifications.
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.
Several creatine forms are sold, including monohydrate, anhydrous, hydrochloride, nitrate, citrate, and blends. Once dissolved, these forms deliver creatine, but they differ in molar mass, solubility, counterions, and water content. Creatine monohydrate has the largest body of published human data among these forms. Questions remain about whether any alternative form offers meaningful advantages in absorption, tolerability, or tissue uptake under practical conditions. The hydrate form's lower creatine content by mass is a compositional fact, not a statement about effectiveness.
Creatine monohydrate is a crystalline compound formed when one molecule of creatine associates with one molecule of water in the solid lattice. Its molecular formula is C4H11N3O3, and its molar mass is about 149.15 grams per mole. The material appears as a white, odorless powder that dissolves sparingly in water at room temperature. The monohydrate designation distinguishes it from anhydrous creatine, which lacks the bound water and has a lower molar mass. This hydrate is the most common commercial form of creatine used in nutritional and research settings.
Manufacturing processes can leave trace amounts of dicyandiamide, creatinine, or residual solvents, depending on the synthetic route and purification steps. Heavy metals, arsenic, and microbial contamination are also monitored for food or pharmaceutical grades. Particle size distribution can affect dissolution behavior and blending uniformity, so it may be specified for certain applications. Analytical results are reported on a dry basis or as-is basis, and the difference matters when comparing certificates of analysis. Open questions remain about how minor impurities influence long-term stability under varied storage conditions.
Stability studies typically examine the effects of temperature, humidity, and light on creatine monohydrate. Sealed containers stored in cool, dry conditions help limit moisture uptake and hydrolysis. Elevated temperature and high relative humidity can accelerate conversion to creatinine, especially in aqueous solutions. In solid dosage forms, excipients and processing steps may also affect stability. Published stability data are not fully consistent across studies because test conditions and analytical methods vary.
Živojinović (nicknamed Bata) was born in the village of Koraćica under the Kosmaj mountain near Mladenovac, at the time Kingdom of Yugoslavia (now Serbia). His father, Dragoljub, was an official and his mother Tiosava was a housewife. He had two sisters, Stanka and Nada, and grew up in a patriarchal household. A conflict between Dragoljub and the Chetniks during World War II forced the family to move to Belgrade. The family lived in Crveni Krst. Young Bata often went with his friends to the cinema, which sparked his interest in acting. Loitering around the "20th October" cinema, he watched AKUD Branko Krsmanović, a Belgrade troupe, through the window for several days until he was welcomed inside. There he befriended Soja Jovanović, instrumental in the developing of Bata's love for acting, Rade Marković, Olivera Marković, Mića Tomić, and Bata Paskaljević. After graduating from acting schools in Niš and Novi Sad, he enrolled at the Drama Academy in Belgrade.
2051–2084. Federal regulations associated with the act are at Title 16 CFR parts 1101 through 1406. These regulations are numerous and include such laws as the Poison Prevention Packaging Act (PPPA), safety standards for such products as bicycle helmets and cigarette lighters, a ban on lead in paint, and a rule concerning size requirements for toys that could be choking hazards for young children.
2-Oleoylglycerol (2OG) is a monoacylglycerol that is found in biologic tissues. Its synthesis is derived from diacylglycerol precursors. It is metabolized to oleic acid and glycerol primarily by the enzyme monoacylglycerol lipase (MAGL). In 2011, 2OG was found to be an endogenous ligand to GPR119. 2OG has been shown to increase glucagon-like peptide-1 (GLP-1) and gastric inhibitory polypeptide (GIP) levels following administration to the small intestine. 2OG has also been discovered to potentiate G protein and not β-arrestin signaling via allosteric binding of the 5-HT2A receptor. 2-Arachidonoylglycerol JZL184
Different active sites are bonded by agonist and antagonist, which means the antagonist obstructs the chain of events that triggers the agonist to produce a response at a point downstream from the agonist binding site on the receptor. It irreversibly binds to the active site. One examples is when Ketamine enters the NMDA receptor's ion channel pore and blocks it, stopping ions from passing through the channels. Also, medication like nifedipine and verapamil stops Ca2+ from entering the cell membrane and so non-selectively prevent medications that act at any receptor that binds to these calcium channels from causing smooth muscle contraction.
Sources: en.wikipedia.org
In 2013, during the Long Shutdown 1, three ISOLDE buildings were demolished. They've been built again as a new single building with a new control room, a data storage room, three laser laboratories, a biology and materials laboratory, and a room for visitors. Another building extension for the MEDICIS project and several others equipped with electrical, cooling and ventilation systems to be used for the HIE-ISOLDE project in the future were also built. In addition, the robots which were installed for the handling of radioactive targets have been replaced with more modern robots. In 2015, for the first time, a radioactive isotope beam could be accelerated to an energy level of 4.3 MeV per nucleon in the ISOLDE facility thanks to the HIE-ISOLDE upgrades. In late 2017, the CERN-MEDICIS facility produced its first radioisotopes and by the end of 2020 had provided external nine hospitals and research facilities with 41 batches of radioisotopes. Phase 2 of the facility's HIE-ISOLDE upgrade was completed in 2018, which allows ISOLDE to accelerate radioactive beams up to 10 MeV per nucleon.
Possibly the most common use of affinity chromatography is for the purification of recombinant proteins. Proteins with a known affinity are protein tagged in order to aid their purification. The protein may have been genetically modified so as to allow it to be selected for affinity binding; this is known as a fusion protein. Protein tags include hexahistidine (His), glutathione-S-transferase (GST), maltose binding protein (MBP), and the Colicin E7 variant CL7 tag. Histidine tags have an affinity for nickel, cobalt, zinc, copper and iron ions which have been immobilized by forming coordinate covalent bonds with a chelator incorporated in the stationary phase. For elution, an excess amount of a compound able to act as a metal ion ligand, such as imidazole, is used. GST has an affinity for glutathione which is commercially available immobilized as glutathione agarose. During elution, excess glutathione is used to displace the tagged protein. CL7 has an affinity and specificity for Immunity Protein 7 (Im7) which is commercially available immobilized as Im7 agarose resin. For elution, an active and site-specific protease is applied to the Im7 resin to release the tag-free protein.
Prior to the development of intradialytic parenteral nutrition in the late 20th century, nutritional management of patients receiving dialysis primarily relied on dietary counselling, liberalized renal diets, and oral nutritional supplements; however, protein–energy wasting (PEW) remained common among patients undergoing maintenance hemodialysis. Efforts to supplement nutritional intake by providing nutrients during the dialysis procedure were attempted. As a result, IDPN became an established therapy to threat malnourished CKD stage 5 dialysis patients in the early 1990s. Generally, the patients received a set formulation containing standard amounts of dextrose, amino acids and lipids regardless of the patient's weight, dialysis time, and complicating co-morbid conditions.
Another form of bioprinting involves an inkjet printer, which is primarily used in biomedical settings. This method prints detailed proteins and nucleic acids. Hydrogels are commonly selected as the bioink. Cells can be printed on to a selected surface media to proliferate and ultimately differentiate. A drawback of this printing method is the ability of the bioinks such as hydrogels to clog the printing nozzle, due to their high viscosity. Ideal inkjet bioprinting involves using a low polymer viscosity (ideally below 10 centipoise), low cell density (<10 million cells/mL), and low structural heights (<10 million cells/mL).
CooA is a homodimeric, heme-containing transcription factor of the CAP/CRP family, with each monomer comprising an N-terminal heme-binding regulatory domain and a C-terminal helix-turn-helix motif that acts as a DNA-binding domain. The N-terminal domain coordinates a b-type heme whose axial ligands differ between species (for example, His-Pro versus His-His), and carbon monoxide (CO) binding to this heme triggers conformational changes that activate DNA binding. The two subunits associate through a coiled-coil-like interface, positioning the paired helix–turn–helix motifs to recognize target palindromic sequences in promoter DNA and thereby regulate genes involved in CO oxidation. Several structures of CooA have been solved, including: RrCooA in the ferrous state (1FT9), ChCooA in the ferrous, imidazole-bound state (2FMY), ChCooA in the ferrous, CO-bound state (2HKX).
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.
A sealed container kept at room temperature and away from moisture is typical. Heat and humidity promote conversion to creatinine and can reduce assay values. Long-term storage under dry conditions helps maintain the original crystalline form.