This is a working overview of HPLC assay, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2025-09-20. Anything still debated is marked as such rather than presented as settled.
In dry solid form, creatine monohydrate is relatively stable when protected from moisture and heat. The crystal lattice includes water, and exposure to high humidity can cause caking or gradual changes in powder flow. Elevated temperatures may accelerate decomposition, particularly if moisture is present. Studies generally report that sealed, dry material retains acceptable purity for extended periods, although exact shelf life depends on packaging and storage conditions. Light exposure is not usually considered a major factor for this compound.
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.
In the body, creatine is synthesized from the amino acids arginine, glycine, and methionine, primarily in the liver and kidneys. It is transported to muscle and other tissues, where it is phosphorylated to phosphocreatine by creatine kinase. This phosphagen system provides a rapid source of adenosine triphosphate during short, intense contractions. Dietary creatine comes mainly from meat and fish, and the body's total pool is influenced by both synthesis and intake.
As a supplement, creatine monohydrate is studied for its effects on muscle performance and recovery. The compound is often described as an ergogenic aid, meaning it may support physical work capacity. Research typically compares it with placebo or other forms, such as citrate or nitrate, under controlled conditions. Questions remain about the optimal dose and long-term effects in different populations, and findings are not uniform across all studies. The monohydrate form remains the most extensively tested.
| Property | Value | Notes |
|---|---|---|
| Typical storage temperature | 15–25 °C | Cool, dry, sealed container; avoid heat |
| Relative humidity | Low; keep below about 60% | Moisture promotes caking and degradation |
| Primary degradation product | Creatinine | Forms by cyclization, especially in solution |
| Common assay method | HPLC with UV or RI detection | Separates creatine from creatinine and related impurities |
| Moisture content | Typically reported as percentage | Measured by Karl Fischer titration or loss on drying |
Solid creatine monohydrate is generally stable when kept dry and protected from extremes of heat and humidity. In the presence of moisture, it can gradually convert to creatinine, a cyclic dehydration product that has little value for phosphocreatine synthesis. Elevated temperatures and acidic conditions accelerate this conversion in solution. Because the reaction is slow in cool, dry storage, typical shelf lives are measured in years rather than weeks. Packaging that limits moisture and oxygen exposure helps maintain purity.
Recommended storage usually involves a sealed container kept at room temperature, away from direct sunlight and moisture. High humidity can cause caking, which changes flow properties and may complicate accurate weighing. Repeated opening of containers exposes the powder to air and moisture, so smaller aliquots can reduce handling effects. Storage temperature ranges are not absolute requirements; they reflect conditions that slow degradation and preserve consistent physical characteristics. Clean, dry tools help prevent contamination during sampling.
Identity and purity are commonly assessed by high-performance liquid chromatography, often with ultraviolet detection, and by spectroscopic techniques such as infrared or nuclear magnetic resonance. These methods can distinguish creatine from creatinine and detect related impurities. Moisture content may be measured by Karl Fischer titration or loss on drying. Particle size, bulk density, and heavy metal limits are additional quality parameters. Not every product is tested by every method, so specifications depend on the intended use and regulatory framework.
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.
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.
Quality control of creatine monohydrate relies on a combination of identity, purity, and moisture tests. High-performance liquid chromatography with ultraviolet detection is widely used to separate creatine from creatinine and other related nitrogenous compounds. Spectroscopic methods such as infrared and nuclear magnetic resonance provide structural confirmation. Because the material is a hydrate, water content is measured separately, often by Karl Fischer titration. These tests together establish whether a lot meets a defined specification.
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.
==== Custom manufacturing ==== The products and services offered by the fine chemical industry fall into two broad categories: (1) "Exclusives" or custom manufacturing (CM) and (2) "standard" or "catalogue" products. "Exclusives", provided mostly under contract research or custom manufacturing arrangements, prevail in business with life science companies; "standards" prevail in other target markets. Service-intense custom manufacturing constitutes the most prominent activity of the fine chemical industry. Custom manufacturing is the antonym of outsourcing. In custom manufacturing, a specialty-chemicals company outsources the process development, pilot plant, and industrial-scale production of an active ingredient, or a predecessor thereof, to one, or a few, fine chemical companies. The intellectual property of the product, and generally also the manufacturing process, stay with the customer. The customer-supplier relationship is governed by an exclusive supply agreement. At the beginning of cooperation, the customer provides a "tech package" which, in its simplest version, includes a laboratory synthesis description and SHE recommendations. In this case, the whole scale up, which comprises a factor of about one million (10 gram → 10 ton quantities), is done by the fine chemical company.
== See also == List of benzodiazepines Benzodiazepine dependence Benzodiazepine withdrawal syndrome Long-term effects of benzodiazepines Lofendazam (1,5-benzodiazepine derivative and partial benzodiazepine receptor agonist) Arfendazam (1,5-benzodiazepine derivative and partial benzodiazepine receptor agonist) Triflubazam (1,5-benzodiazepine derivative and partial benzodiazepine receptor agonist) CP-1414S (1,5-benzodiazepine derivative and partial benzodiazepine receptor agonist) Premazepam (pyrrolodiazepine derivative and partial benzodiazepine receptor agonist) Nordazepam (1,4-benzodiazepine derivative and partial benzodiazepine receptor agonist)
Taxol is a tetracyclic diterpene, and the biosynthesis of diterpenes starts with an FPP molecule being elongated by the addition of an IPP molecule in order to form geranylgeranyl diphosphate (GGPP). The biosynthesis of Taxol contains nineteen steps. These 19 steps can be considered in several steps, with the first step being the formation of the taxane skeleton, which then undergoes a series of oxygenations. Following the oxygenations, two acetylations and a benzoylation occur on the intermediate. The oxygenation of the taxane core is believed to occur on C5 and C10, C2 and C9, C13 followed by C7, and a C1 hydroxylation later on in the pathway. Later in the pathway, an oxidation at C9 forms a ketone functional group and an oxetane, forming the intermediate baccatin III. The final steps of the pathway include the formation of a C13-side chain which is attached to baccatin III. The biosynthesis of Taxol is illustrated in more detail in the figure, with steps 1-7 all occurring in the enzyme taxadiene synthase (TS on the figure). Taxol's biosynthesis begins with E,E,E-GGPP losing pyrophosphate via an SN1 mechanism (step 1 in the figure). The double-bond attacks the cation via electrophilic addition, yielding a tertiary cation and creating the first ring closure (step 2). Another electrophilic attack occurs, further cyclizing the structure by creating the first 6-membered ring and creating another tertiary cation (step 3). An intramolecular proton transfer occurs, attacking the verticillyl cation (step 4) and creating a double bond, yielding a tertiary cation.
During each turn of the cycle, two carbon atoms leave the cycle as CO2 in the decarboxylation reactions catalyzed by isocitrate dehydrogenase and alpha-ketoglutarate dehydrogenase. Thus each turn of the citric acid cycle oxidizes an acetyl-CoA unit while regenerating the oxaloacetate molecule with which the acetyl-CoA had originally combined to form citric acid. The decarboxylation reactions occur before malate is formed in the cycle. Malate is the only substance that can be removed from the mitochondrion to enter the gluconeogenic pathway to form glucose or glycogen in the liver or any other tissue. There can therefore be no net conversion of fatty acids into glucose. Only plants possess the enzymes to convert acetyl-CoA into oxaloacetate from which malate can be formed to ultimately be converted to glucose.
Sources: en.wikipedia.org
The prokineticin receptor is a G protein-coupled receptor which binds the peptide hormone prokineticin. There are two variants each encoded by a different gene (PROKR1, PROKR2). These receptors mediate gastrointestinal smooth muscle contraction and angiogenesis.
The fungus is highly toxic, and is responsible for the majority of fatal mushroom poisonings worldwide. Its biochemistry has been researched intensively for decades, and 30 grams (1.1 ounces), or half a cap, of this mushroom is estimated to be enough to kill a human. On average, one person dies a year in North America from death cap ingestion. The toxins of the death cap mushrooms primarily target the liver, but other organs, such as the kidneys, are also affected. Symptoms of death cap mushroom toxicity usually occur 6 to 12 hours after ingestion. Symptoms of ingestion of the death cap mushroom may include nausea and vomiting, which is then followed by jaundice, seizures, and coma, which will lead to death. The mortality rate of ingestion of the death cap mushroom is believed to be around 10–30%. Some authorities strongly advise against putting suspected death caps in the same basket with fungi collected for the table and to avoid even touching them. Furthermore, the toxicity is not reduced by cooking, freezing, or drying. Poisoning incidents usually result from errors in identification. Recent cases highlight the issue of the similarity of A. phalloides to the edible paddy straw mushroom (Volvariella volvacea), with East and Southeast Asian immigrants in Australia and the West Coast of the U.S. falling victim. In an episode in Oregon, four members of a Korean family required liver transplants. Many North American incidents of death cap poisoning have occurred among Laotian and Hmong immigrants, since it is easily confused with A.
The three substrates of this enzyme are taxusin, oxygen, and a proton. It uses a reduced nicotinamide adenine dinucleotide (NADH) cofactor bound to a heme in cytochrome P450 to give 7β-hydroxytaxusin and water as products. The enzyme is found in the yew tree Taxus cuspidata and is part of the pathway for the biosynthesis of taxol.
Sources: en.wikipedia.org
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.
Creatine can lose a water molecule and cyclize into creatinine, especially in aqueous solution and at elevated temperatures. This is a chemical degradation process rather than microbial spoilage.
High-performance liquid chromatography is commonly used to quantify creatine and detect creatinine. Identity can be confirmed with spectroscopy or other instrumental methods.
It is a compound made of creatine bound to one water molecule. It appears as a white crystalline powder and is the most common solid form of creatine used in research and supplements.