This is a working overview of HPLC-UV, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2025-08-16 and is reviewed periodically as new material appears.
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.
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.
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.
Quality control for creatine monohydrate begins with identity confirmation and assay determination. Laboratories commonly use high-performance liquid chromatography with ultraviolet detection, often after derivatization or using a suitable column, to quantify creatine. Karl Fischer titration measures water content, which helps verify the monohydrate stoichiometry. Additional tests screen for heavy metals, residual solvents, and microbial contamination depending on the intended use. These tests establish composition and purity rather than biological effect.
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.
| Property | Value | Notes |
|---|---|---|
| Typical storage temperature | 15–25 °C | Cool, dry, sealed conditions slow conversion to creatinine. |
| Moisture sensitivity | Moderate | Absorbs water from humid air, which can cause caking. |
| Primary purity method | HPLC-UV | Separates creatine from creatinine and related impurities. |
| Moisture method | Karl Fischer titration | Measures water content; loss on drying is an alternative. |
| Degradation product | Creatinine | Forms by dehydration, especially in solution or humid heat. |
In the body, creatine is obtained from dietary meat and fish and is also synthesized from arginine, glycine, and methionine. Muscle stores creatine and phosphocreatine, which participate in the rapid regeneration of adenosine triphosphate during short, intense activity. The monohydrate form is used in research because it is chemically defined, stable as a dry solid, and relatively inexpensive to produce. Questions remain about whether other creatine forms offer meaningful advantages in absorption or tissue retention, and findings vary across studies and populations.
Creatine monohydrate is a crystalline compound formed from creatine and one molecule of water. Creatine itself is a nitrogen-containing organic acid that occurs in vertebrate muscle and other tissues. The monohydrate designation refers to the water included in the crystal lattice, not to water added during manufacturing. Its chemical formula is commonly written as C4H9N3O2·H2O. The solid is typically a white, odorless powder with low solubility in water at room temperature. It is one of several creatine forms described in scientific and commercial literature.
The compound was identified in the nineteenth century after chemists isolated a nitrogenous substance from meat extracts. Later work established its role in muscle energy metabolism and its conversion to phosphocreatine. Chemical synthesis of creatine followed, and industrial production made the monohydrate widely available as a purified powder. Interest expanded in the late twentieth century when researchers began studying creatine supplementation and muscle physiology. Historical accounts sometimes differ on exact dates and attributions, but the broad sequence from tissue extracts to synthetic production is well documented.
Several creatine forms are sold, including monohydrate, anhydrous, hydrochloride, nitrate, citrate, and blends. Once dissolved, these forms deliver creatine, but they differ in molar mass, solubility, counterions, and water content. Creatine monohydrate has the largest body of published human data among these forms. Questions remain about whether any alternative form offers meaningful advantages in absorption, tolerability, or tissue uptake under practical conditions. The hydrate form's lower creatine content by mass is a compositional fact, not a statement about effectiveness.
Creatine monohydrate is a crystalline compound formed when one molecule of creatine associates with one molecule of water in the solid lattice. Its molecular formula is C4H11N3O3, and its molar mass is about 149.15 grams per mole. The material appears as a white, odorless powder that dissolves sparingly in water at room temperature. The monohydrate designation distinguishes it from anhydrous creatine, which lacks the bound water and has a lower molar mass. This hydrate is the most common commercial form of creatine used in nutritional and research settings.
Creatine is synthesized endogenously in humans, mainly in the liver, kidney, and pancreas, from the amino acids arginine, glycine, and methionine. Skeletal muscle stores much of the body's creatine, where it participates in the phosphocreatine system that buffers adenosine triphosphate during short, intense contractions. Dietary sources include meat and fish, so omnivorous diets provide additional creatine beyond endogenous production. Supplemental creatine monohydrate supplies the same molecule found in food and tissues, not a distinct drug or hormone. Research interest centers on its role in cellular energy transfer and its effects on muscle and other tissues.
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.
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.
Creatine monohydrate is a crystalline organic compound formed from creatine and water in a one-to-one ratio. It belongs to the guanidino family and contains a methylated guanidine group attached to an acetate-like chain. The solid is commonly described as a white, odorless powder with a mildly bitter taste. Its molecular formula is C4H11N3O3·H2O, and the hydrated form is the most widely traded grade. The compound occurs naturally in vertebrate muscle and brain tissue, where it participates in rapid energy buffering.
The longest-lived vertebrates have been variously described as: Large parrots (macaws and cockatoos can live up to 80–100 years in captivity) Koi (a Japanese species of fish, allegedly living up to 200 years, though generally not exceeding 50 – a specimen named Hanako was reportedly 226 years old upon her death) Tortoises (Seychelles tortoise) (193 years) Tuatara (a New Zealand reptile species, 100–200+ years) Eels, the so-called Brantevik Eel (Swedish: Branteviksålen) is thought to have lived in a water well in southern Sweden since 1859, which makes it over 150 years old. It was reported that it had died in August 2014 at an age of 155. Whales (bowhead whale) (Balaena mysticetus about 200 years)—Although this idea was unproven for a time, recent research has indicated that bowhead whales recently killed still had harpoons in their bodies from about 1890, which, along with analysis of amino acids, has indicated a maximum life span of "177 to 245 years old". Greenland sharks are currently the vertebrate species with the longest known lifespan. An examination of 28 specimens in one study published in 2016 determined by radiocarbon dating that the oldest of the animals that they sampled had lived for about 392 ± 120 years (a minimum of 272 years and a maximum of 512 years). The authors further concluded that the species reaches sexual maturity at about 150 years of age.
=== Peritoneal folds === Understanding the macroscopic structure of the mesenteric organ meant that associated structures—the peritoneal folds and congenital and omental adhesions—could be better appraised. The small intestinal mesenteric fold occurs where the small intestinal mesentery folds onto the posterior abdominal wall and continues laterally as the right mesocolon. During mobilization of the small intestinal mesentery from the posterior abdominal wall, this fold is incised, allowing access to the interface between the small intestinal mesentery and the retroperitoneum. The fold continues at the inferolateral boundary of the ileocaecal junction and turns cephalad as the right paracolic peritoneal fold. This fold is divided during lateral to medial mobilization, permitting the surgeon to serially lift the right colon and associated mesentery off the underlying fascia and retroperitoneum. At the hepatic flexure, the right lateral peritoneal fold turns and continues medially as the hepatocolic peritoneal fold. Division of the fold in this location permits separation of the colonic component of the hepatic flexure and mesocolon off the retroperitoneum. Interposed between the hepatic and splenic flexures, the greater omentum adheres to the transverse colon along a further band or fold of peritoneum. Dissection through this allows access to the cephalad (top) surface of the transverse mesocolon. Focal adhesions frequently tether the greater omentum to the cephalad aspect of the transverse mesocolon.
Other possible applications of MOFs are in gas purification, in gas separation, in water remediation, in catalysis, as conducting solids and as supercapacitors. The synthesis and properties of MOFs constitute the primary focus of reticular chemistry (from Latin reticulum, "small net"). In contrast to MOFs, covalent organic frameworks (COFs) are made entirely from light elements (H, B, C, N, and O) with extended structures. Susumu Kitagawa, Richard Robson and Omar Yaghi were awarded the Nobel Prize in Chemistry in 2025 for their work on MOFs.
=== Grand Lodge of Louisiana === In 1803, the US Government made the Louisiana Purchase. On April 30, 1812, Louisiana became the eighteenth US state. By the year 1815, the Grand Lodge of Louisiana had grown large enough to return to Cuba, where in Havana, they chartered Union Fraternal de Caridad No. 14. Two other Lodges, Nos. 11 and 14, were also chartered within the next three years. There is some historical disagreement on whether EI Templo de la Divina Pastora No. 19, chartered in Matanzas in 1818, and La Rectitud No. 22, chartered in Havana in 1822, were connected with the York Rite.
=== Treating trauma and painful wounds === Persistent chronic pain associated with non-healing wounds is caused by tissue (nociceptive) or nerve (neuropathic) damage and is influenced by dressing changes and chronic inflammation. Chronic wounds take a long time to heal and patients can experience chronic wounds for many years. Chronic wound healing may be compromised by coexisting underlying conditions, such as venous valve backflow, peripheral vascular disease, uncontrolled edema and diabetes mellitus. If wound pain is not assessed and documented it may be ignored and/or not addressed properly. It is important to remember that increased wound pain may be an indicator of wound complications that need treatment, and therefore practitioners must constantly reassess the wound as well as the associated pain. Optimal management of wounds requires holistic assessment. Documentation of the patient's pain experience is critical and may range from the use of a patient diary, (which should be patient driven), to recording pain entirely by the healthcare professional or caregiver. Effective communication between the patient and the healthcare team is fundamental to this holistic approach. The more frequently healthcare professionals measure pain, the greater the likelihood of introducing or changing pain management practices. At present there are few local options for the treatment of persistent pain, whilst managing the exudate levels present in many chronic wounds.
Sources: en.wikipedia.org
Treatment of depression: Used in adults who may present with symptoms of anxiety, low mood, lack of enthusiasm, and restlessness. Treatment of anxiety: Indicated for patients with anxiety disorders, especially when depression is also present or when there is associated asthenia (unexplained fatigue or weakness). Management of asthenia: Used for conditions characterized by fatigue, low energy, and diminished motivation, frequently seen with mood disturbances. Psychosomatic and neurotic disorders: Recommended for depressive neuroses, psychogenic depression, masked depression, neurasthenia, and psychosomatic affections where anxiety, depression, or apathy are prominent. Menopausal depression: Often indicated for mood changes associated with menopause. Depression in alcoholics and drug addicts: Used in cases where mood disorders accompany substance dependence.
=== May === 1 May – Bob Brockie, biologist, cartoonist (National Business Review) and columnist (Dominion Post) (born 1932). 2 May – Sir Bob Jones, property magnate, writer, and politician, founder of the New Zealand Party (1983) (born 1939). 5 May Shane Richardson, motorcycle racer (born c. 1996). Shane Solomon, lawyer and Māori leader (Waikato Tainui) (born 1963). 6 May – Bill McCaw, rugby union player (Southland, national team), oldest living All Black (since 2023) (born 1927). 9 May – Fred Graham, rugby union player (New Zealand Māori), educator and sculptor, Te Tohu mō Te Arikinui Dame Te Atairangikaahu (2017), Arts Foundation of New Zealand Icon (since 2018) (born 1928). 13 May – Danny Lendich, businessman and midget car racing team owner, introduced Wendy's to New Zealand (1988) (born 1944). 14 May – Lionel Hill-Smith, Empire Games hurdler (1950) (born 1929). 15 May – Durham Havill, local politician and businessman, Mayor of Westland (1989–1998) (born 1944). 16 May – Tuppy Diack, rugby union player (Otago, Southland, national team) and administrator, president of the Otago Rugby Football Union (2005) (born 1930). 17 May – Clive Rennie, educator, principal of Rangitikei College (1986–1991), Mountainview High School (1997–2000) and Otago Boys' High School (2000–2014) (born 1944). 18 May – John Simpson, silversmith and fine arts academic (University of Canterbury) (born 1925). 21 May – Frank Gibson Jr., jazz drummer and drum tutor (born 1946). 23 May – Roger Bridge, businessman and political party official (National) (born 1958).
Inhibitory postsynaptic potential (IPSP) A type of synaptic potential that makes a neuron less likely to fire an action potential, usually by allowing chloride or potassium ions to enter the cell. Innervation The supply of nerves to a specific body part. In neuroscience, it describes how neurons connect to and control muscles, glands, or other neurons. Input resistance A measure of how much a neuron's membrane resists incoming current. It influences how strongly the cell responds to synaptic inputs. Insular cortex A region buried within the lateral sulcus, involved in interoception, emotion, taste, and awareness of bodily states. Intelligence quotient (IQ) A standardized measure of cognitive ability. In neuroscience, research explores how brain structure and function relate to individual differences in IQ. Interneuron A neuron that connects other neurons within a neural circuit, typically within the same brain region or spinal segment. Often inhibitory and essential for reflexes and signal modulation. Intracranial pressure The pressure inside the skull, exerted by brain tissue, blood, and cerebrospinal fluid. Abnormal levels can cause headaches, vision problems, or brain damage. Intracellular recording A technique used to measure the voltage or current inside a neuron, providing detailed information about membrane potential and ionic currents. Ion channel A pore-forming membrane protein that allows ions to pass in and out of neurons. Ion channels are critical for generating and propagating electrical signals.
=== Area associations (Landschaftsverbände) === The most populous state of North Rhine-Westphalia is uniquely divided into two area associations (Landschaftsverbände), one for the Rhineland, and one for Westphalia-Lippe. This arrangement was meant to ease the friction caused by uniting the two culturally different regions into a single state after World War II. The Landschaftsverbände now have very little power. The constitution of Mecklenburg-Vorpommern at §75 states the right of Mecklenburg and Vorpommern to form Landschaftsverbände, although the old border between these two constituent parts of the state is not represented in the current administrative division.
After removing the skin, the unripe fruit can be sliced thin and deep fried in hot oil to produce chips. This thin preparation of plantain is known as tostones, patacones or plataninas in some of Central American and South American countries, platanutres in Puerto Rico, mariquitas or chicharritas in Cuba and chifles in Ecuador and Peru. However, in Cuba, the Dominican Republic, Guatemala, Puerto Rico, and Venezuela, tostones instead refers to thicker twice-fried patties (see below). In Cuba, plantain chips are called mariquitas. They are sliced thinly, and fried in oil until golden colored. They are popular appetizers served with a main dish. In Colombia they are known as platanitos and are eaten with suero atollabuey as a snack. Tostada refers to a green, unripe plantain which has been cut into sections, fried, flattened, fried again, and salted. These tostadas are often served as a side dish or a snack. They are also known as tostones or patacones in many Latin American countries. In Honduras, banana chips are called tajadas, which may be sliced vertically to create a variation known as plantain strips. In Africa, ipekere are plantain chips by the Yorubas It is made with varying stages of plantain, from very ripe, ripe to semi unripe and unripe. It is also fried as chips in various ways: plain, salted, seasoned or with various degrees of spiciness. There are different consistency in textures by preferences. Chips fried in coconut oil and sprinkled with salt, called upperi or kaya varuthathu, are a snack in South India in Kerala.
Sources: en.wikipedia.org
== Multiple valves == Multiple check valves can be connected in series. For example, a double check valve is often used as a backflow prevention device to keep potentially contaminated water from siphoning back into municipal water supply lines. There are also double ball check valves in which there are two ball/seat combinations sequentially in the same body to ensure positive leak-tight shutoff when blocking reverse flow; and piston check valves, wafer check valves, and ball-and-cone check valves.
== Organs and tissues affected by IGF-1 == Since many distinct tissue types express the IGF-1 receptor, IGF-1's effects are diverse. It acts as a neurotrophic factor, inducing the survival of neurons. It may catalyse skeletal muscle hypertrophy, by inducing protein synthesis, and by blocking muscle atrophy. It is protective for cartilage cells, and is associated with activation of osteocytes, and thus may be an anabolic factor for bone. Since at high concentrations it is capable of activating the insulin receptor, it can also complement for the effects of insulin. Receptors for IGF-1 are found in vascular smooth muscle, while typical receptors for insulin are not found in vascular smooth muscle.
==== Miscellaneous ==== The acute effects of LSD normally last between 6 and 12 hours depending on dose, tolerance, and age. In a modern study, the effects of the dose of LSD given lasted for up to 12 hours and were closely correlated with the concentrations of LSD present in circulation over time, with no acute tolerance observed.
=== Scintigraphy/radionuclide imaging === Scintigraphy can be used to measure the extent and distribution of the amyloid throughout the body, including the liver, kidney, spleen, and heart. A radiolabelled serum amyloid P component can be administered to a patient intravenously and the P component pools to the amyloid deposit proportional to the size of the deposit. The labeling of the P component can then be pictured by a gamma camera. Technetium radionuclide scans can now reliably diagnosis cardiac amyloidosis, with certain scanning methods having greater than 99% sensitivity (but only 91% specific for amyloidosis). In this method of imaging, radiolabeled technetium is injected into the body where it binds to cardiac amyloid deposits. A subsequent scan is taken to determine where the tracer stays, therefore highlighting the amyloid deposition in the heart. This method allows for a noninvasive definitive diagnosis of cardiac amyloidosis (as in the past an endomyocardial biopsy was required)
Flareups continued to occur starting on June 19, sending more smoke into the air which continued to impact the local Boyle Heights community. The warehouse also experienced severe structural damage during the fire. The solar panels on the roof and the collapse of roof structure made fighting the fire difficult. On June 18, the shelter-in-place order was briefly reinstated after crews detected hydrogen fluoride, indicating that a lithium-ion battery (likely from a battery-operated forklift) had ignited inside the facility. Officials also raised concerns that the estimated 85 million pounds of frozen food (including bread, poultry, pork, and beef) inside the facility—no longer kept cold by the damaged refrigeration system—would begin to decompose, creating foul odors and potential biohazards, which Mayor Bass compared to food spoiling during a prolonged power outage. Health concerns intensified as the fire continued, with officials extending particulate matter advisories and Los Angeles Unified School District relocating students from several nearby schools due to air quality impacts. Regulatory monitors and sensors recorded improved PM2.5 levels in Central and Southeast Los Angeles, the San Gabriel Valley, and the San Fernando Valley, though air quality near the fire itself remained elevated, with "Very Unhealthy" conditions measured throughout the day in Boyle Heights; other areas ranged from "Good" to "Moderate" for PM2.5.
Sources: en.wikipedia.org
Solid product can remain within specification for years when stored dry and sealed, but expiration dates reflect manufacturer testing and regulatory conventions. Moisture and heat increase conversion to creatinine, so storage conditions matter more than the printed date alone. Degradation is gradual and can be monitored by purity testing.
Purity is typically evaluated by chromatographic separation with ultraviolet detection, sometimes supported by spectroscopic identity tests. Moisture and creatinine content are common quality parameters. Results depend on the analytical method, sample preparation, and specification limits.
Clumping occurs when powder absorbs moisture, causing particles to stick together. Humidity, temperature changes, and repeated container opening promote this effect. Clumps do not necessarily indicate chemical degradation, but they can affect weighing and mixing.
Karl Fischer titration is a standard method for measuring water content in solid and liquid samples. The result helps confirm the expected monohydrate stoichiometry. Loss-on-drying can also indicate moisture but may not distinguish water from other volatile substances.