The short version of Karl Fischer titration fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2025-09-27 and is reviewed periodically as new material appears.
In aqueous solution, creatine monohydrate exists mainly as a zwitterion, carrying both a positive guanidinium charge and a negative carboxylate charge. This charge separation raises water solubility relative to many neutral organic solids and helps explain its behavior in analytical separations. The monohydrate can lose its water of crystallization under sustained heat or low humidity, converting toward anhydrous creatine. Such transitions matter for mass balance calculations because the hydrate contributes water mass that is not part of the active creatine molecule.
The term creatine monohydrate is often shortened to creatine in casual usage, though other creatine forms exist, including citrate, nitrate, and hydrochloride salts. These alternative forms differ in solubility, pH behavior, and the amount of creatine delivered per unit mass. Regulatory categories vary by country: some jurisdictions treat it as a food ingredient, while others place it under supplement or drug frameworks depending on claims and presentation. Standard reference texts list it as a naturally occurring nitrogenous organic acid rather than a vitamin or mineral.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical formula | C4H11N3O3·H2O | Hydrated form includes one water molecule per creatine unit. |
| Molar mass | 149.15 g/mol | Calculated for the monohydrate form. |
| Appearance | White crystalline powder | Common commercial grade is odorless or nearly odorless. |
| Solubility in water | Moderately soluble | Solubility increases with temperature and depends on pH. |
| Common synonyms | Creatine hydrate; N-methylguanidinoacetic acid | Monohydrate distinguishes it from anhydrous creatine. |
In 1930, safety glass became standard on all Ford cars. In the 1930s, plastic surgeon Claire L. Straith and physician C. J. Strickland advocated the use of seat belts and padded dashboards. Strickland founded the Automobile Safety League of America. In 1934, GM performed the first barrier crash test. In 1936, the Hudson Terraplane came with the first back-up brake system. Should the hydraulic brakes fail, the brake pedal would activate a set of mechanical brakes for the back wheels. In 1937, Chrysler, Plymouth, DeSoto, and Dodge added such items as a flat, smooth dash with recessed controls, rounded door handles, a windshield wiper control made of rubber, and the back of the front seat heavily padded to provide protection for rear passengers.
Helices observed in proteins can range from four to over forty residues long, but a typical helix contains about ten amino acids (about three turns). In general, short polypeptides do not exhibit much α-helical structure in solution, since the entropic cost associated with the folding of the polypeptide chain is not compensated for by a sufficient amount of stabilizing interactions. In general, the backbone hydrogen bonds of α-helices are considered slightly weaker than those found in β-sheets, and are readily attacked by the ambient water molecules. However, in more hydrophobic environments such as the plasma membrane, or in the presence of co-solvents such as trifluoroethanol (TFE), or isolated from solvent in the gas phase, oligopeptides readily adopt stable α-helical structure. Furthermore, crosslinks can be incorporated into peptides to conformationally stabilize helical folds. Crosslinks stabilize the helical state by entropically destabilizing the unfolded state and by removing enthalpically stabilized "decoy" folds that compete with the fully helical state. It has been shown that α-helices are more stable, robust to mutations and designable than β-strands in natural proteins, and also in artificially designed proteins.
Before amylin deposition was associated with diabetes, already in 1901, scientists described the phenomenon of "islet hyalinization", which could be found in some cases of diabetes. A thorough study of this phenomenon was possible much later. In 1986, the isolation of an aggregate from an insulin-producing tumor was successful, a protein called IAP (Insulinoma Amyloid Peptide) was characterized, and amyloids were isolated from the pancreas of a diabetic patient, but the isolated material was not sufficient for full characterization. This was achieved only a year later by two research teams whose research was a continuation of the work from 1986.
Sources: en.wikipedia.org
Initial letters are used where there is no ambiguity: C cysteine, H histidine, I isoleucine, M methionine, S serine, V valine. No other amino acids in this set begin with each of those letters. Where arbitrary assignment is needed, the structurally simpler amino acids are given precedence: A alanine, G glycine, L leucine, P proline, T threonine. For example, alanine is simpler than arginine or asparagine, the other amino acids starting with "a". F PHenylalanine and R aRginine are assigned by being phonetically suggestive, W tryptophan is assigned based on the double ring being visually suggestive to the bulky letter W, K lysine and Y tyrosine are assigned as alphabetically nearest to their initials L and T (note that U was avoided for its similarity with V, while X was reserved for undetermined or atypical amino acids); for tyrosine the mnemonic tYrosine was also proposed, D aspartate was assigned arbitrarily, with the proposed mnemonic asparDic acid; E glutamate was assigned in alphabetical sequence being larger by merely one methylene –CH2– group, N asparagine was assigned arbitrarily, with the proposed mnemonic asparagiNe; Q glutamine was assigned in alphabetical sequence of those still available (note again that O was avoided due to similarity with D), with the proposed mnemonic Qlutamine.
Amylin, or islet amyloid polypeptide (IAPP), is a 37-residue peptide hormone. It is co-secreted with insulin from the pancreatic β-cells in the ratio of approximately 100:1 (insulin:amylin). Amylin plays a role in glycemic regulation by slowing gastric emptying and promoting satiety, thereby preventing spikes in blood glucose levels after a meal. IAPP is processed from an 89-residue coding sequence. Proislet amyloid polypeptide (proIAPP, proamylin, proislet protein) is produced in the pancreatic beta cells (β-cells) as a 67 amino acid, 7404 Dalton pro-peptide and undergoes post-translational modifications including protease cleavage to produce amylin.
From the 17th century, and before modern developments in organic chemistry nomenclature, acetone was given many different names. They included "spirit of Saturn", which was given when it was thought to be a compound of lead and, later, "pyro-acetic spirit" and "pyro-acetic ester". Prior to the name "acetone" being coined by French chemists, it was named "mesit" (from the Greek μεσίτης, meaning mediator) by Carl Reichenbach, who also said that methyl alcohol consisted of mesit and ethyl alcohol. Names derived from mesit include mesitylene and mesityl oxide which were first synthesised from acetone. In 1839, the name "acetone" began to be used, because it was obtained from acetic acid. Unlike many compounds with the acet- prefix which have a 2-carbon chain, acetone has a 3-carbon chain. That has caused confusion because there can not be a ketone with 2 carbons. The prefix refers to acetone's relation to vinegar (acetum in Latin, also the source of the words "acid" and "acetic"), rather than its chemical structure.
Sources: en.wikipedia.org
In common usage, yes, but technically creatine monohydrate is one specific hydrated salt form. Other creatine forms exist and differ in composition and properties. The monohydrate is the most studied and most widely available grade.
Yes. Each creatine molecule in the crystal is associated with one water molecule. That water contributes to the total mass but is not part of the creatine molecule itself. Heating or drying can remove some or all of this water.
It occurs naturally in meat and fish, and the human body also makes and stores creatine. Food sources provide varying amounts depending on the type and preparation. The compound is not considered an essential dietary nutrient for adults because the body can synthesize it.
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.