HPLC-UV comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Last reviewed on 2026-03-09. Where a claim depends on a specific study, the study is described rather than over-claimed.
Analytical laboratories commonly use high-performance liquid chromatography to separate creatine from creatinine and related impurities. Ion chromatography, nuclear magnetic resonance, and titration assays can also quantify the compound. Water content is measured by Karl Fischer titration or loss on drying, because the monohydrate has a defined theoretical water fraction. Particle size, bulk density, and flowability are physical properties that affect blending and capsule filling. These measurements support quality control and help verify that a lot matches its specification.
Regulatory status varies by country. In the United States, creatine monohydrate is sold as a dietary supplement ingredient, while in the European Union it is placed on the market as a food supplement component. Some jurisdictions have established purity monographs or permitted health claims, while others treat it as a novel food or require notification. Product labels may state the amount of creatine monohydrate or the equivalent creatine content, and the two figures can differ. Independent testing programs sometimes check identity, potency, and contaminant limits.
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.
Solid creatine monohydrate is relatively stable when kept dry and sealed, but heat and moisture accelerate its conversion to creatinine. This degradation involves intramolecular cyclization, a process that removes water and forms a less useful compound for phosphocreatine metabolism. Powder stored under cool, dry conditions can remain within specification for extended periods, though exact shelf life depends on packaging, humidity, and initial purity. Aqueous solutions degrade faster than dry powder, with pH and temperature influencing the rate. Because degradation is gradual, analytical testing is used to confirm potency at manufacture and during stability studies.
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.
| Property | Value | Notes |
|---|---|---|
| Typical storage temperature | 15-25 °C | Sealed container; protect from moisture and direct heat. |
| Theoretical water content | About 12.1% | One water molecule per creatine molecule. |
| Primary degradation product | Creatinine | Formed by cyclization, especially in aqueous solution. |
| Common analytical method | HPLC-UV | Used to separate creatine from creatinine and related impurities. |
| Regulatory classification (U.S.) | Dietary supplement ingredient | Other jurisdictions may classify it as a food supplement or novel food depending on rules. |
Stability studies examine how creatine monohydrate changes under controlled temperature and humidity. The solid is generally stable when kept dry, but moisture can promote hydrolysis to creatinine, especially in solution or at elevated temperatures. Color, odor, and assay values are monitored over time to detect degradation. Because degradation pathways depend on storage conditions, shelf-life claims should specify the tested packaging, temperature, and humidity. Open questions remain about the long-term behavior of different crystal habits and particle sizes.
Regulatory treatment of creatine monohydrate varies by country and intended use. In some jurisdictions it is sold as a dietary supplement, while in others it may be treated as a food ingredient or a pharmaceutical raw material. Pharmacopeial monographs, where available, define identification, assay limits, and impurity thresholds. Manufacturers often follow these monographs or internal specifications to ensure batch-to-batch consistency. Analytical method validation is important because different methods can yield different apparent purity values if sample preparation or detection conditions are not controlled.
Creatine monohydrate is a crystalline compound formed from creatine and one water molecule in its solid lattice. Creatine itself is a nitrogen-containing organic acid involved in energy transfer in muscle and other tissues. The monohydrate form is the most common solid form used in research and commercial products because it is stable and easy to handle. The term "monohydrate" refers to the fixed one-to-one ratio of water to creatine in the crystal, not to moisture content. This distinction matters when comparing labels or calculating creatine content.
In chemical terms, creatine monohydrate is often described as N-(aminoiminomethyl)-N-methylglycine monohydrate, though nomenclature varies. Its solid state consists of zwitterionic creatine molecules linked with water through hydrogen bonding. The compound dissolves in water, but dissolution rate depends on particle size, temperature, and agitation. Once dissolved, the hydrate water becomes part of the solvent, leaving free creatine in solution. The monohydrate is not the same as creatine anhydrous, which lacks the water of crystallization and has a higher creatine fraction by mass.
Most ants are generalist predators, scavengers, and indirect herbivores, but a few have evolved specialised ways of obtaining nutrition. It is believed that many ant species that engage in indirect herbivory rely on specialized symbiosis with their gut microbes to upgrade the nutritional value of the food they collect and allow them to survive in nitrogen poor regions, such as rainforest canopies. Leafcutter ants (Atta and Acromyrmex) feed exclusively on a fungus that grows only within their colonies. They continually collect leaves which are taken to the colony, cut into tiny pieces and placed in fungal gardens. Ergates specialise in related tasks according to their sizes. The largest ants cut stalks, smaller workers chew the leaves and the smallest tend the fungus. Leafcutter ants are sensitive enough to recognise the reaction of the fungus to different plant material, apparently detecting chemical signals from the fungus. If a particular type of leaf is found to be toxic to the fungus, the colony will no longer collect it. The ants feed on structures produced by the fungi called gongylidia. Symbiotic bacteria on the exterior surface of the ants produce antibiotics that kill bacteria introduced into the nest that may harm the fungi.
==== Protein C and Protein S ==== Protein C is a major physiological anticoagulant. It is a vitamin K-dependent serine protease enzyme that is activated by thrombin into activated protein C (APC). Protein C is activated in a sequence that starts with Protein C and thrombin binding to a cell surface protein thrombomodulin. Thrombomodulin binds these proteins in such a way that it activates Protein C. The activated form, along with protein S and a phospholipid as cofactors, degrades FVa and FVIIIa. Quantitative or qualitative deficiency of either (protein C or protein S) may lead to thrombophilia (a tendency to develop thrombosis). Impaired action of Protein C (activated Protein C resistance), for example by having the "Leiden" variant of Factor V or high levels of FVIII, also may lead to a thrombotic tendency.
A worldwide summary of more than one hundred human studies reported a median of 22.1 μmol/L for serum α-tocopherol and defined α-tocopherol deficiency as less than 12 μmol/L. It cited a recommendation that serum α-tocopherol concentration be ≥30 μmol/L to optimize health benefits. In contrast, the U.S. Dietary Reference Intake text for vitamin E concluded that a plasma concentration of 12 μmol/L was sufficient to achieve normal ex vivo hydrogen peroxide-induced hemolysis. A 2014 review defined less than 9 μmol/L as deficient, 9-12 μmol/L as marginal, and greater than 12 μmol/L as adequate. Regardless of which definition is used, vitamin E deficiency is rare in humans, occurring as a consequence of abnormalities in dietary fat absorption or metabolism rather than from a diet low in vitamin E. Cystic fibrosis and other fat malabsorption conditions can result in low serum vitamin E. One example of a genetic abnormality in metabolism is mutations of genes coding for alpha-tocopherol transfer protein (α-TTP). Humans with this genetic defect exhibit a progressive neurodegenerative disorder known as ataxia with vitamin E deficiency (AVED) despite consuming normal amounts of vitamin E. Large amounts of alpha-tocopherol as a dietary supplement are needed to compensate for the lack of α-TTP. Bariatric surgery as a treatment for obesity can lead to vitamin deficiencies. Long-term follow-up reported a 16.5% prevalence of vitamin E deficiency. There are guidelines for multivitamin supplementation, but adherence rates are reported to be less than 20%.
Mary Margaret Dalligan, lately Home Care Worker, London Borough of Southwark. For services to the community. Celeste Dandeker, Artistic Director, Candoco. For services to Dance and to Disabled People. Peter Daniel, Chairman, Ridgemond Training, Stevenage, Hertfordshire. For services to Training and Young People. Wasim Darr, President, UK Islamic Mission (Southern Region). For services to Community Relations. Harriet Emily Rhys-Davies. For political and public service. Irene Joyce Davies. For services to the community in Pantymwyn, Flintshire. Joyce Mary Davies. For services to the British Red Cross Society in Shropshire. Catherine Elizabeth Dawson, Chief Administrative Dental Officer, Grampian Health Board. For services to Dentistry. Geoffrey Michael Day. For services to the Oil Industry. Hugh Ludlow de Quetteville. For charitable services. Simon Patrick Dell, Constable, Devon and Cornwall Constabulary. For services to the Police. William Ernest Denny. For services to Soldiers', Sailors' and Airmen's Families Association in Warwickshire. Royland Charles Derham, General Secretary, the TS Vindicatrix Association. For services to the Merchant Navy. Joyce Muriel Dewey. For services to the community in Lymington, Hampshire. Frederick Gains Dobson. For services to the Ex-Service Fellowship Centres. Ingnd Julia Dodd. For political services. John Doherty. For services to Disabled ex-Servicemen and Women. Maurice Francis Donaghy, Assistant Controller, The Stamp Office, Board of Inland Revenue. Hilda Donaldson. For services to Education. Margaret Agnes Donaldson.
== Discovery == Apelin is a peptide hormone that was identified in 1998 by Masahiko Fujino and his colleagues at Gunma University and Takeda Pharmaceutical Company. In 2013, a second peptide hormone named Elabela was found by Bruno Reversade to also act as an endogenous ligand to the APLNR.
Sources: en.wikipedia.org
== Other hormone-producing structures == Many body organs not normally considered endocrine organs contain isolated cell clusters that secrete hormones. Examples include the heart (atrial natriuretic peptide); gastrointestinal tract organs (gastrin, secretin, and others); the placenta (hormones of pregnancy—estrogen, progesterone, and others); the kidneys (erythropoietin and renin); the thymus; skin (cholecalciferol); and adipose tissue (leptin and resistin).
Dipeptidase 2 (DPEP2) is a protein which in humans is encoded by the DPEP2 gene. DPEP2 belongs to the membrane-bound dipeptidase (EC 3.4.13.19) family. These enzymes hydrolyze a variety of dipeptides, including leukotriene D4, the beta-lactam ring of some antibiotics, and cystinyl-bis-glycine (cys-bis-gly) formed during glutathione degradation.
Overview of the RNAi process, from Cambridge University's The Naked Scientists Animation of the RNAi process, from Nature NOVA scienceNOW explains RNAi – A 15-minute video of the Nova broadcast that aired on PBS, 26 July 2005 Silencing Genomes Archived 10 August 2019 at the Wayback Machine RNA interference (RNAi) experiments and bioinformatics in C. elegans for education. From the Dolan DNA Learning Center of Cold Spring Harbor Laboratory. RNAi screens in C. elegans in a 96-well liquid format and their application to the systematic identification of genetic interactions (a protocol) 2 American 'Worm People' Win Nobel for RNA Work, from NY Times Molecular Therapy web focus: "The development of RNAi as a therapeutic strategy", a collection of free articles about RNAi as a therapeutic strategy. GenomeRNAi: a database of phenotypes from RNA interference screening experiments in Drosophila melanogaster and Homo sapiens RNAi tools Archived 19 June 2018 at the Wayback Machine Pre-designed and custom RNA Interference tools
== Actinide partitioning: complexation mechanism == The selective separation of actinides from the PUREX raffinate by advanced processes needs new extracting agents, which must possess a more pronounced affinity towards actinides over lanthanides and other products mostly present in the acidic fuel dissolution. The design and the synthesis of efficient extracting agents rely on a deep knowledge of the complexation mechanism involved in the extraction process. Moreover, the structure and the stability of the ligand complexes with An(III) and Ln(III) upon extraction process, and the ligand selectivity need to be investigated. Research is being devoted to design more N-donor extracting agents, which show promising selectivity towards actinides.
Sources: en.wikipedia.org
== Etymology == The term "botany" comes from the Ancient Greek word botanē (βοτάνη) meaning "pasture", "herbs" "grass", or "fodder"; Botanē is in turn derived from boskein (Greek: βόσκειν), "to feed" or "to graze". Traditionally, botany has also included the study of fungi and algae by mycologists and phycologists respectively, with the study of these three groups of organisms remaining within the sphere of interest of the International Botanical Congress.
Blood or urine tests measure hCG. These can be pregnancy tests. hCG-positive can indicate an implanted blastocyst and mammalian embryogenesis or can be detected for a short time following childbirth or pregnancy loss. Tests can be done to diagnose and monitor germ cell tumors and gestational trophoblastic diseases. Concentrations are commonly reported in thousandth international units per milliliter (mIU/mL). The international unit of hCG was originally established in 1938 and has been redefined in 1964 and in 1980. At the present time, 1 international unit is equal to approximately 2.35×10−12 moles, or about 6×10−8 grams. It is also possible to test for hCG to have an approximation of the gestational age.
==== Efp ==== Efp, or estrogen-inducible RING-finger protein, is an E3 ubiquitin ligase whose overexpression has been shown to be the major cause of estrogen-independent breast cancer. Efp's substrate is 14-3-3 protein which negatively regulates cell cycle.
Sources: en.wikipedia.org
A sealed container at room temperature, away from moisture and direct heat, is suitable for most solid material. Keeping the lid closed limits water uptake and caking. Long-term storage in a refrigerator is not necessary if the powder remains dry.
Heat, moisture, and prolonged time in solution promote conversion to creatinine. The reaction is faster at higher temperatures and at pH values far from neutral. Dry powder is much more stable than dissolved material.
Common methods include high-performance liquid chromatography for creatine and creatinine, plus water-content analysis by Karl Fischer titration. Heavy metals, residual solvents, and microbial limits may also be tested. A specification may list total creatine content and impurity limits.
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.