HPLC assay is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Updated 2026-06-18. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
Creatine monohydrate is stable under dry, cool conditions but can degrade when exposed to moisture and heat. In solution, it undergoes hydrolysis to creatinine, a cyclic derivative with little role in phosphagen energy transfer. The rate of conversion increases with temperature, storage time, and acidic or alkaline pH. Solid material kept in a sealed container at room temperature generally retains its composition for extended periods. Moisture uptake is a primary concern because it can accelerate breakdown and caking.
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.
| Property | Value | Notes |
|---|---|---|
| Typical storage temperature | 15–25 °C | Cool, dry, sealed |
| Relative humidity | Below 60% | Moisture promotes caking and degradation |
| Degradation product | Creatinine | Forms by cyclization, especially in solution |
| Assay method | HPLC with UV detection | Often paired with identity tests |
| Aqueous stability | Hours to days at room temperature | Depends on pH, temperature, concentration |
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.
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.
Creatine monohydrate is a crystalline compound formed from creatine and one molecule of water. Its systematic name is N-(aminoiminomethyl)-N-methylglycine monohydrate, and it appears as a white, odorless powder with limited solubility in water. The monohydrate is the most common solid form used in research and commercial products because it is stable under dry conditions. The anhydrous form lacks the water of crystallization and differs slightly in molar mass. Both forms participate in the same biochemical reactions once dissolved.
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.
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.
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.
As early as 1731, starch was extracted from the potato and used as a substitute for wheat starch. It is also used in pastries and cookies; it is in particular an ingredient of the Gâteau de Savoie; it is added, mixed with water, to omelets and is used for sauces in smaller quantities than flour. Potato starch was used to produce artificial honey that looked like honey from Narbonne. It is still abundantly produced in the 21st century. The extraction of this starch gives rise to an important industrial activity: the "starch factory".
He will be strong enough to get up and two days later he leaves the home.However, even in 1934 he was suspicious of the idea that the treatment was pure conditioned reflex – "though vomiting is one of the ways that apomorphine relives the patient, I do not believe it to be its main therapeutic effect." – and by 1948 he wrote:It is now twenty-five years since I began treating cases of anxiety and alcoholism with apomorphine, and I read my first paper before this Society fourteen years ago. Up till then I had thought, and, unfortunately, I said in my paper, that the virtue of the treatment lay in the conditioned reflex of aversion produced in the patient. This statement is not even a half truth… I have been forced to the conclusion that apomorphine has some further action than the production of a vomit.This led to his development of lower-dose and non-aversive methods, which would inspire a positive trial of his method in Switzerland by Dr Harry Feldmann.
Interestingly, the full-length CUX1 protein purified from insect cells exhibited DNA binding kinetics similar to that of CR1CR2, suggesting that the Cut homeodomain may not be active in the context of the full-length protein.
Sources: en.wikipedia.org
=== Laboratory Analysers === Automated analysers, by the association of robotics and spectrophotometry, have allowed these last decades better reproducibility of the results, in particular in medical biochemistry and hematology. Efficiency and productivity can be enhanced by automating the pre-analytical processing, including barcode reading, sorting, centrifuging, and aliquoting specimens. The analysers must undergo daily controls prior to performing patient testing. Analysers must also undergo daily, weekly and monthly maintenance. Quality management involves reviewing quality control trends to detect emerging problems in instrument calibration, correlating results between instruments that perform similar testing, and running standardized samples to prove linearity and precision. Some laboratory processes involve automated analysis combined with manual review by technologists. For example, when hematology analysers flag samples as abnormal, automated white blood cell differential counts may be superseded by manual differential counts using stained slides read at the microscope or scanned by digital imaging software. Laboratory technologists may flag abnormal samples for pathologist review. The pathologist may recommend additional testing, such as flow cytometry to identify lymphoma or leukemia cells, or cytology to characterize solid tumor cells.
C13H9−CH2−OC(O)NHR + (CH2)5NH → (CH2)5NH+2 + [C13H8−CH2−OC(O)NHR]− [C13H8−CH2−OC(O)NHR]− → C13H8=CH2 + −OC(O)NHR −OC(O)NHR + (CH2)5NH+2 → HOC(O)NHR + (CH2)5NH HOC(O)NHR → CO2 + RNH2 C13H8=CH2 + (CH2)5NH → C13H9−CH2N(CH2)5
==== Persistent pulmonary hypertension ==== Persistent pulmonary hypertension (PPHN) is a serious and life-threatening, but very rare, lung condition that occurs soon after the birth of the newborn. Newborn babies with PPHN have high pressure in their lung blood vessels and are not able to get enough oxygen into their bloodstream. About 1 to 2 babies per 1000 babies born in the U.S. develop PPHN shortly after birth, and often they need intensive medical care. It is associated with about a 25% risk of significant long-term neurological deficits. A 2014 meta analysis found no increased risk of persistent pulmonary hypertension associated with exposure to SSRIs in early pregnancy and a slight increase in risk associates with exposure late in pregnancy; "an estimated 286 to 351 women would need to be treated with an SSRI in late pregnancy to result in an average of one additional case of persistent pulmonary hypertension of the newborn". A review published in 2012 reached conclusions similar to those of the 2014 study.
== January 8, 1982 (Friday) == To end a federal antitrust suit that had been brought in 1974 by the U.S. Department of Justice, the telephone monopoly American Telephone & Telegraph (AT&T) agreed to sell its 22 individual Bell System companies that had controlled most U.S. telephone lines. On the same day, the Department of Justice dropped its 12-year-old antitrust suit against International Business Machines (IBM), ending a trial that had started on May 19, 1975. The Umkhonto we Sizwe paramilitary force of South Africa's anti-apartheid African National Congress, carried out an attack on the construction site of the Koeberg Nuclear Power Station, planned to be the white South African government's first nuclear power plant, causing 500 million rands worth of damage and setting back the completion date by 18 months. The first White House meeting concerning Project Excalibur, the proposed Strategic Defense Initiative (nicknamed the "Star Wars defense") for the United States against an enemy missile attack, took place as Edward Teller, Karl Bendetsen, William Wilson and Joseph Coors made a one-hour presentation to U.S. President Ronald Reagan for a satellite with lasers that could destroy nuclear missiles after their launch.
Sources: en.wikipedia.org
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.
It can cyclize into creatinine, particularly in water or under heat. Creatinine does not support phosphocreatine energy buffering in the same way.
Laboratories commonly use chromatographic methods such as HPLC, along with spectroscopy and titration, to confirm identity and quantity. Moisture, elemental impurities, and microbial limits may also be tested.
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.