A practical reference on Karl Fischer titration: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2026-03-04 and is reviewed periodically as new material appears.
Commercial creatine monohydrate is typically a white to off-white powder with low odor. It is commonly sold as a fine powder, micronized powder, or larger crystals, but these are physical forms of the same chemical. Purity grades vary, and products may contain small amounts of related substances such as creatinine, dicyandiamide, or moisture. The monohydrate is often selected for supplements and research because its production is well established and its behavior in water is predictable. Analytical certificates usually report assay, loss on drying, and heavy metals.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical name | N-(aminoiminomethyl)-N-methylglycine monohydrate | Nomenclature varies across sources. |
| Common synonyms | Creatine hydrate; creatine monohydrate | “Monohydrate” specifies one water per creatine. |
| Appearance | White to off-white crystalline powder | Particle size and flowability vary by grade. |
| Solubility class | Soluble in water; slightly soluble in ethanol | Dissolution increases with temperature and stirring. |
| Typical storage | Tightly closed container at 15–25 °C | Protect from moisture and excessive heat. |
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 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.
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.
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.
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.
Commercial creatine monohydrate is typically manufactured through chemical synthesis, often starting from sarcosine and cyanamide. The resulting material is crystallized, washed, and dried to a specified hydrate content. Finished lots are tested for identity, purity, moisture, and heavy metals before release. Because the compound can cyclize to creatinine under heat or prolonged storage in solution, manufacturers control temperature and humidity during processing. The solid itself is relatively stable when kept dry and sealed, but moisture uptake can cause caking and complicate accurate assay.
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.
==== Distribution ==== The apparent volume of distribution of modafinil is 0.326 to 0.8 L/kg body weight. The plasma protein binding of modafinil is approximately 60%. It is mostly (90%) bound to albumin. Both armodafinil and esmodafinil are substrates of P-glycoprotein, but the clinical significance of this is unknown.
=== 24 January === At least 70 people were killed in an RSF drone strike on the maternity ward of the Saudi Hospital in El Fasher that also destroyed its emergency department. The SAF claimed to have broken the siege around the Signal Corp's base in Khartoum. The RSF denied the claims. The SAF also claimed to have broken the siege around its General Headquarters in Khartoum and retook the El-Jeili oil refinery. The SAF and allied militias repelled an RSF attack on El Fasher following the expiration of the latter's ultimatum for the SAF to withdraw. The JDF claimed it had killed more than 400 RSF militants, destroyed more than 25 vehicles and captured 30 others. Ayub Osman Nahar resigned as an advisor to Hemedti, saying that he refused to be part of the RSF's atrocities against civilians and accusing the group of burning villages and killing civilians in North Darfur and Gezira State.
Critics of long residency hours trace the problem to the fact that a resident has no alternatives to positions that are offered, meaning residents must accept all conditions of employment, including very long work hours, and that they must also, in many cases, contend with poor supervision. This process, they contend, reduces the competitive pressures on hospitals, resulting in low salaries and long, unsafe work hours. Criticisms of limiting the work week include disruptions in continuity of care and limiting training gained through involvement in patient care. Similar concerns have arisen in Europe, where the Working Time Directive limits doctors to 48 hours per week averaged out over a 6-month reference period.
This advance enables the enantioselective construction of three-dimensional, sp³-rich molecules used in drug discovery and total synthesis. Sulfonyl hydrazides are commercially available as reagent feedstock.
=== Pain === Amitriptyline alleviates painful diabetic neuropathy. It is recommended by a variety of guidelines as a first or second-line treatment. It is as effective for this indication as gabapentin or pregabalin but less well tolerated. Amitriptyline is as effective at relieving pain as duloxetine. Combination treatment of amitriptyline and pregabalin offers additional pain relief for people whose pain is not adequately controlled with one medication and is usually safe. Amitriptyline in certain formulations may also induce the level of sciatic-nerve blockade needed for local anesthesia therein. Here, it has been demonstrated to be of superior potency to bupivacaine, a customary long-acting local anesthetic. Low doses of amitriptyline moderately improve sleep disturbances and reduce pain and fatigue associated with fibromyalgia. It is recommended for fibromyalgia accompanied by depression by Association of the Scientific Medical Societies in Germany and as a second-line option for fibromyalgia, with exercise being the first line option, by European League Against Rheumatism. Combinations of amitriptyline and fluoxetine or melatonin may reduce fibromyalgia pain better than either medication alone. There is some (low-quality) evidence that amitriptyline may reduce pain in cancer patients. It is recommended only as a second-line therapy for non-chemotherapy-induced neuropathic or mixed neuropathic pain if opioids did not provide the desired effect. Moderate evidence exists in favor of amitriptyline use for atypical facial pain.
Sources: en.wikipedia.org
== 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.
== Childhood obesity == Childhood obesity and adolescent obesity have also increased in Brazil. National surveys and international reports have identified Brazil as one of the countries experiencing a rapid rise in obesity among children and adolescents. Public health experts have expressed concern that increasing childhood obesity may contribute to future increases in diabetes, cardiovascular disease, and healthcare expenditures. The World Obesity Federation has highlighted childhood obesity as an emerging public health challenge in Brazil and throughout Latin America.
Macrocrystalline aqueous suspensions of progesterone as well as microspheres of progesterone were investigated as potential progestogen-only injectable contraceptives and combined injectable contraceptives (with estradiol) by the late 1980s and early 1990s but were never marketed. Aqueous solutions of water-insoluble steroids were first developed via association with colloid solubility enhancers in the 1940s. An aqueous solution of progesterone for use by intravenous injection was marketed by Schering AG under the brand name Primolut Intravenous by 1962. One of its intended uses was the treatment of threatened abortion, in which rapid-acting effect was desirable. An aqueous solution of progesterone complexed with cyclodextrin to increase its water solubility was introduced for use by once-daily subcutaneous injection in Europe under the brand name Prolutex in the mid-2010s. In the 1950s, long-acting parenteral progestins such as hydroxyprogesterone caproate, medroxyprogesterone acetate, and norethisterone enanthate were developed and introduced for use by intramuscular injection. They lacked the need for frequent injections and the injection site reactions associated with progesterone by intramuscular injection and soon supplanted progesterone for parenteral therapy in most cases.
In another direction, Morris et al reported the use of GdL as a 'molecular trigger' to predict and control the order of gelation. Chirality also plays an essential role in gel formation, and even changing the chirality of a single amino acid from its natural L-amino acid to its unnatural D-amino acid can significantly impact the gelation properties, with the natural forms not forming gels. Furthermore, aromatic interactions play a key role in hydrogel formation as a result of π- π stacking driving gelation, shown by many studies.
CAS registry number – Chemical identifierPages displaying short descriptions of redirect targets Chemical nomenclature – Systematic naming of chemical compounds Commission on Isotopic Abundances and Atomic Weights – International scientific committee European Association for Chemical and Molecular Sciences Institute for Reference Materials and Measurements (IRMM) – Promotes a common European measurement system International Chemical Identifier (InChI) – Identifier for chemical substances International Union of Biochemistry and Molecular Biology (IUBMB) – International non-governmental organization International Union of Pure and Applied Physics (IUPAP) – Non-governmental organization for physics development List of chemical elements naming controversies National Institute of Standards and Technology (NIST) – Measurement standards laboratory in the United States Simplified molecular-input line-entry system (SMILES) – Chemical species structure notationPages displaying short descriptions of redirect targets
Sources: en.wikipedia.org
Once we draw out the potential stereoisomers, we see that the two structures are super-imposable in three dimensions, and therefore are the self-same molecule. For this reason fentanyl does not have R/S assignments. The second case studied here is of 3-methylfentanyl. There are two potential stereocenters, at the 4-carbon and also at the 3-carbon, where there is additionally a methyl group. Now, we mark both 3 and 4 carbon as potential stereocenters with an asterisk (*), and see how many potential stereoisomers we can eliminate. We see that of the four permutations of stereoisomers, none are super-imposable in three dimensions, meaning each is a unique stereoisomer and that both potential stereocenters were true. This gives four potential R/S assignments, 1R3S, 1R3R, 1S3S, 1S3R. What is particularly interesting and quite a contrast from the previous example of cyclohexanol, is the stereocenter at C-4 is indeed a true stereocenter here, whereas in the previous example of cyclohexanol as an analogy to fentanyl, the C-4 was not a true stereocenter. This changed because the modification of the C-3 carbon without an equivalent change on the C-2 carbon created an imbalance between two formerly identical substituents, creating a novel stereocenter where there was not one previously. This is why it is so important to follow the 4 steps in the above procedure every time, as "inherited procedural wisdom" may hold an organic chemist back in finding the true or correct answer.
genotyping The process of determining differences in the genotype of an individual by examining the DNA sequences in the individual's genome using bioassays and comparing them to another individual's sequences or a reference sequence.
=== Bombing of Laos === In February 1970, several senators led by J. William Fulbright and Stu Symington first learned that the United States had been bombing Laos since December 1964, which led to complaints in Congress about the "secret war" in Laos. Nixon reluctantly decided to admit to the "secret war", and directed Kissinger to issue the necessary statement to the media. Kissinger's statement admitted to the bombing of Laos, but also claimed: "No American stationed in Laos has ever been killed in ground combat operations". Two days later, it emerged that a U.S. Army captain had been killed while fighting in Laos and subsequently the Pentagon admitted that in the period February 1969-February 1970 a total of 27 Americans had been killed in Laos. Kissinger claimed that he had not lied, maintaining that all Americans killed in Laos were in "hot pursuit" when chasing the enemy from South Vietnam into Laos, but this argument made no impression. Nixon stated: "No one cares about B-52 strikes in Laos, but people worry about our boys out there". Nixon refused to see Kissinger for the next week, saying that his statement about Laos had caused him to drop 11 points in the public opinion polls.
During their formation in bone marrow, and in the liver and spleen in fetuses, red blood cells contain a cell nucleus, which is usually absent in the mature cells that circulate in the bloodstream. Nucleated red blood cells are normal in newborn babies, but when detected in children and adults, they indicate an increased demand for red blood cells, which can be caused by bleeding, some cancers and anemia. Most analyzers can detect these cells as part of the differential cell count. High numbers of nucleated red cells can cause a falsely high white cell count, which will require adjusting.
Sources: en.wikipedia.org
It is a solid form of creatine that contains one water molecule per creatine molecule in the crystal lattice. The hydrate water is part of the crystal structure rather than loose moisture. The term is often used for the common crystalline powder grade.
Creatine anhydrous lacks the water of crystallization and therefore contains a higher creatine fraction by mass. The monohydrate is more common in commerce and research because it is stable and easy to handle. The two forms are not identical in solid state, though both yield creatine when dissolved.
Creatine is the base molecule, while creatine monohydrate is a hydrate of that molecule. Once dissolved, the hydrate water becomes part of the solvent and free creatine is present. In casual usage the names are often shortened to creatine, but the solid forms differ.
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.