If you have been reading about Karl Fischer titration 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 2026-03-24. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
| 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 |
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.
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.
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.
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.
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.
Corticotropin-releasing hormone (CRH), which regulates ACTH secretion from the anterior pituitary gland Somatostatin, which regulates growth hormone secretion from the anterior pituitary gland Thyrotropin-releasing hormone (TRH), which regulates TSH and prolactin secretion
== Causes == Mitochondrial disorders may be caused by mutations (acquired or inherited), in mitochondrial DNA (mtDNA), or in nuclear genes that code for mitochondrial components. They may also be the result of acquired mitochondrial dysfunction due to adverse effects of drugs, infections, or other environmental causes.
For services to Life Saving. Geoffrey Francis Norris, General Medical Practitioner, London. For services to Medicine. Arthur Joseph Nutter. For services to the Lieutenancy in Lancashire. John O'Neil, lately Principal Lecturer and Course Leader of PGCE Art and Design, University of Wales Institute, Cardiff. For services to Art Education and Teacher Training. Martin Offiah. For services to Rugby Football. Enid Rosalind Oliver. For services to the community in Ashford, Kent. William James Orford. For services to Cricket in the West Midlands. Vera Overs. For services to the community in Martindale, Cumbria. Clifford Owen. For services to the Chorley and District Talking Newspaper, Lancashire. Pamela Mary Owen. For services to the community, particularly the NHS, in Welshpool, Powys. Anthony Gerald Palmer. For services to the War Pensions Committee in East Anglia. Sarah Faith, The Honourable Mrs. Palmer. For services to the community, particularly the British Red Cross Society, in Berkshire. Isobel Marilyn Park. For services to the Scout Association in Dumfries. Gordon Seymour Passmore, Member, London Borough of Wandsworth. For services to Local Government. Norman Henry Pattenden, Special Operations Manager, North & South Railways Ltd. For services to the Railways Industry. William Evans Pattison. For services to Mountain Rescue. Robert John Patton. For services to the Engineering Industry. Christine Anne Pendlebury, Personal Secretary, Home Office. Philippa Helen Perks. For services to the community in Wrington, Bristol.
Spironolactone may be more effective than birth-control pills in the treatment of acne, and the combination of spironolactone with a birth-control pill may have greater effectiveness for acne than either alone. In addition, some clinical research has found that flutamide is more effective than spironolactone in the treatment of acne. In one study, flutamide decreased acne scores by 80% within 3 months, whereas spironolactone decreased symptoms by only 40% in the same period. However, the use of flutamide for acne is limited by its liver toxicity. Bicalutamide is a potential alternative to flutamide for acne as well. Spironolactone can be considered as a first-line treatment for acne in those who have failed other standard treatments such as topical therapies and under certain other circumstances, although this is controversial due to the side effects of spironolactone and its teratogenicity. Insufficient clinical evidence exists to compare the effectiveness of spironolactone with other antiandrogens for female-pattern hair loss. The effectiveness of spironolactone in the treatment of both acne and hirsutism appears to be dose-dependent, with higher doses being more effective than lower doses. Higher doses also have greater side effects, such as menstrual irregularities.
Sources: en.wikipedia.org
In 2020, potassium was the 33rd most commonly prescribed medication in the U.S., with more than 17 million prescriptions. Other uses of potassium supplements include preventing the formation of kidney stones, a condition that can lead to renal complications if left untreated. Potassium has a role in bone health. It contributes to the acid-base equilibrium in the body and helps protect bone tissue. For individuals with type 2 diabetes, potassium supplementation may be necessary: potassium is essential for the secretion of insulin by pancreatic beta cells, which helps regulate glucose levels. Excessive potassium intake can have adverse effects, such as gastrointestinal discomfort and disturbances in heart rhythm. Potassium chloride tablets are specifically associated with pill esophagitis.
Semi-closed rebreather technology is sometimes used in diver carried surface supplied gas extenders, mainly to reduce helium use. Some units also function as an emergency gas supply using on-board bailout cylinders: The US Navy MK29 rebreather can extend the duration of the Flyaway Mixed Gas System diving operations by five times while retaining the original mixed-gas storage footprint on the support ship. The Soviet IDA-72 semi-closed rebreather has a scrubber endurance of 4 hours on surface supply, and bailout endurance at 200m of 40 minutes on on-board gas. The US Navy Mark V Mod 1 heliox mixed gas helmet has a scrubber canister mounted on the back of the helmet and an inlet gas injection system which recirculates the breathing gas through the scrubber to remove carbon dioxide and thereby conserve helium. The injector nozzle would blow 11 times the volume of the injected gas through the scrubber.
=== Air === Manchester Airport lies just 4 miles (6.4 km) along the A538 to the north-west, but Wilmslow lies away from the approach and departure routes; it therefore does not suffer from aircraft noise as Hale Barns and Heald Green do.
Half-Life 2: Episode Three is a canceled first-person shooter game developed by Valve. It was planned as the last in a trilogy of episodic games continuing the story of Half-Life 2 (2004). Valve announced Episode Three in May 2006, with a release planned for 2007. Following the cliffhanger ending of Episode Two (2007), it was widely anticipated. Episode Three was to be set in the Arctic and introduce elements such as an ice gun and a blob-like enemy. Marc Laidlaw, the writer for the Half-Life series, intended it to end the Half-Life 2 story arc. Little information was released over the following years, and in 2011 Wired described it as vaporware. Valve eventually canceled Episode Three as they had become fatigued with Half-Life and could not settle on a direction. Additionally, they wanted to create more ambitious games and felt limited by the episodic format. They delayed development of a new Half-Life game until their new game engine, Source 2, was complete. Laidlaw left Valve in 2016. In 2017, he released a short story that journalists speculated was a summary of the Episode Three plot. In response, fans launched projects attempting to recreate Episode Three. After canceling several further Half-Life games, Valve released a virtual reality game, Half-Life: Alyx, in 2020.
A theoretical prediction estimated this to be −80‰ to −95‰ for steranes, −90‰ to −95‰ for hopanes, and −70‰ to −95‰ for typical cycloparaffins at 0−100°C. At the temperature of the oil window and gas window, the equilibrium fractionation between different group of organic molecules is relatively small, as compared with large primary signals. The study of hydrogen isotopes of fossil fuels has been applied as proxies and tools in the following aspects:
Sources: en.wikipedia.org
Simultaneously, the government tried a direct negotiation with the ETA leadership but the "Algiers talks" did not lead to any result; on the contrary, the group perpetrated some of the bloodiest attacks in its history: the Hipercor bombing, in Barcelona, and the Zaragoza barracks bombing. The government then sought to reach a great "anti-terrorist" pact that would also include democratic Basque nationalism, which was finally achieved with the signing of the Ajuria Enea Pact in January 1988. A few months later, two policemen, José Amedo and Michel Domínguez were arrested, accused of being involved in the kidnapping of Segundo Marey among other crimes committed by the GAL, and with the aggravating circumstance that they had counted on the reserved funds of the Ministry of the Interior to carry out the attacks. The knowledge of this fact forced the Minister of the Interior José Barrionuevo to resign and he was replaced by José Luis Corcuera. The consolidation of the democratic system included the development of the rights and freedoms recognized in the Constitution of 1978.
== Further reading == Ye, Yanqi; Yu, Jicheng; Gu, Zhen (2015). "Versatile Protein Nanogels Prepared by In Situ Polymerization". Macromolecular Chemistry and Physics. 217 (3): 333–343. doi:10.1002/macp.201500296. Yan, Ming; Ge, Jun; Liu, Zheng; Ouyang, Pingkai (2006). "Encapsulation of Single Enzyme in Nanogel with Enhanced Biocatalytic Activity and Stability". Journal of the American Chemical Society. 128 (34): 11008–9. Bibcode:2006JAChS.12811008Y. doi:10.1021/ja064126t. PMID 16925402. Reese, Chad E.; Mikhonin, Alexander V.; Kamenjicki, Marta; Tikhonov, Alexander; Asher, Sanford A. (2004). "Nanogel Nanosecond Photonic Crystal Optical Switching". Journal of the American Chemical Society. 126 (5): 1493–6. Bibcode:2004JAChS.126.1493R. doi:10.1021/ja037118a. PMID 14759207. Lee, Eun Seong; Kim, Dongin; Youn, Yu Seok; Oh, Kyung Taek; Bae, You Han (2008). "A Virus-Mimetic Nanogel Vehicle". Angewandte Chemie International Edition. 47 (13): 2418–21. Bibcode:2008ACIE...47.2418L. doi:10.1002/anie.200704121. PMC 3118583. PMID 18236507. Hasegawa, Urara; Nomura, Shin-Ichiro M.; Kaul, Sunil C.; Hirano, Takashi; Akiyoshi, Kazunari (2005). "Nanogel-quantum dot hybrid nanoparticles for live cell imaging". Biochemical and Biophysical Research Communications. 331 (4): 917–21. Bibcode:2005BBRC..331..917H. doi:10.1016/j.bbrc.2005.03.228. PMID 15882965. Du, Jin-Zhi; Sun, Tian-Meng; Song, Wen-Jing; Wu, Juan; Wang, Jun (2010). "A Tumor-Acidity-Activated Charge-Conversional Nanogel as an Intelligent Vehicle for Promoted Tumoral-Cell Uptake and Drug Delivery".
=== Acidic Ca2+ store === This is a blanket term that encompasses a spectrum of acidic vesicles that include endosomes, lysosomes, and lysosome-related organelles and secretory vesicles and acidocalcisomes. They are a highly dynamic continuum of vesicles with a rich variety of established biochemical roles in cells, to which Ca2+ storage can now be added. Their luminal pH is one characteristic that distinguishes a given vesicle class from another: where endosomes are weakly acidic (pH 6-6.5), lysosomes are typically the most acidic (pH 4.5-5.0) and secretory vesicles are typically pH 5.5. Ca2+ is seen to be increasingly important for endo-lysosomal function, e.g. trafficking and autophagy. Aberrations in Ca2+ signals can have pathophysiological consequences, including lysosomal storage diseases such as Niemann–Pick disease, type C and Mucolipidosis IV. When NAADP mobilizes Ca2+ from these stores, the pH of the stores concomitantly increases (becomes more alkaline), as testified by studies in sea urchin egg, mammalian heart and pancreas. Whether this has consequences for vesicle (or NAADP) function remains to be seen, but luminal pH is usually crucial for resident protein activity.
== Methods == Several methods for cell lysis exist, sometimes used in combination. Examples include liquid homogenization, freeze thawing, and physical disruption such as sonication, or the use of hypotonic solutions that cause osmotic swelling and eventual bursting of the cell.
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.
Purity is commonly assessed by HPLC, which separates creatine from related compounds such as creatinine. Water content is measured separately by Karl Fischer titration. Together these results help calculate the actual creatine content in a sample.