Everything below concerns system suitability. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-05-18. Where a claim depends on a specific study, the study is described rather than over-claimed.
Separation performance depends on particle size, pore size, column length, and the chemistry of the stationary phase. Smaller particles generally improve efficiency but require higher pressure and suitable instrumentation. The mobile phase often contains buffers and organic solvents that influence retention and selectivity. Testing labs select conditions based on the analytes, sample matrix, and required sensitivity. Method development frequently involves screening several columns and solvent mixtures before a final set of conditions is chosen.
High-performance liquid chromatography is an analytical technique that separates components in a liquid sample by passing them through a packed column under pressure. A pump delivers a mobile phase at a controlled flow rate, and an injector introduces the sample into the stream. Differences in how analytes partition between the mobile phase and the stationary phase cause them to exit the column at different times. Detection then records a signal proportional to the amount of each separated substance. The resulting chromatogram provides retention times and peak areas for identification and quantification.
Instrumentation includes a solvent delivery system, an autosampler, a column oven, and one or more detectors. Reversed-phase columns with chemically modified silica are widely used, but normal-phase, ion-exchange, size-exclusion, and affinity modes exist for specific separations. Detectors may rely on ultraviolet absorbance, fluorescence, refractive index, or mass spectrometry. Column temperature, mobile phase composition, and flow rate are adjusted to improve resolution. System pressure is monitored because rising pressure can indicate column blockage or deteriorating packing.
Routine quality control uses system suitability, blank injections, check standards, and control samples to detect drift or contamination. System suitability criteria may specify minimum resolution, maximum tailing factor, and a permitted range for repeated injections. Blank injections reveal carryover or solvent contamination, while check standards confirm calibration accuracy over a batch. Control samples with known analyte levels can show whether results remain within statistical limits. When a control result falls outside limits, the analyst investigates the cause and may invalidate affected results before repeating the batch.
Documentation and traceability are central to regulated HPLC testing. Records typically include instrument logs, column history, mobile-phase preparation, sample preparation, injection sequences, raw chromatograms, and audit trails. Electronic systems may require user access controls, time-stamped changes, and backup procedures. Training records show that analysts are qualified for assigned methods. Audits and inspections check whether written procedures match actual practice and whether deviations are documented. These controls support reproducibility and allow results to be reconstructed if questions arise later.
| Property | Value | Notes |
|---|---|---|
| Separation principle | Differential partitioning | Analytes distribute between mobile and stationary phases. |
| Mobile phase | Liquid solvent mixture | Composition controls retention and selectivity. |
| Stationary phase | Packed column particles | Often chemically bonded silica. |
| Typical detector | UV-Vis or photodiode array | Mass spectrometry is also common. |
| Common synonym | High-performance liquid chromatography | Abbreviated as HPLC. |
In quality control laboratories, HPLC testing supports batch release, raw material checks, stability studies, and impurity profiling. A validated method defines sample preparation, instrument settings, calibration, and acceptance criteria. Analysts compare results with specifications and investigate out-of-specification outcomes before a batch is approved. Documentation includes chromatograms, integration records, audit trails, and reagent details. Because results influence product decisions, laboratories follow formal quality systems and data integrity rules. The exact tests and limits depend on the material, its intended use, and the applicable regulatory framework.
Method validation examines whether an HPLC procedure is suitable for its intended purpose. Common parameters include accuracy, precision, specificity, linearity, range, detection limit, quantification limit, and robustness. Accuracy describes closeness to a true or accepted value, while precision describes agreement among repeated measurements. Specificity shows whether the method can measure the analyte without interference from related substances. Robustness tests small deliberate changes in flow, temperature, or solvent composition. Validation is not a one-time event; methods may need partial revalidation after changes to instruments, columns, sample handling, or specification limits. Regulatory guidance provides frameworks, but some details remain method-specific.
ISBN 978-1-119-54212-4. OCLC 1083261548. Stvrtinová V, Jakubovský J, Hulín I (1995). Pathophysiology: Principles of Disease. Computing Centre, Slovak Academy of Sciences: Academic Electronic Press. Swartz, Mark H. (2010). Textbook of Physical Diagnosis: History and Examination (6th ed.). Saunders/Elsevier. ISBN 978-1-4160-6203-5. Concise Oxford Companion to the English Language 1998 entries on classical compound and combining form Taber, Clarence Wilbur; Thomas, Clayton L.; Venes, Donald (2001). Taber's cyclopedic medical dictionary (Ed. 19, illustrated in full color ed.). Philadelphia: F.A.Davis Co. ISBN 0-8036-0655-9. ISSN 1065-1357. Waquet, Françoise (2001). Latin, or the Empire of a Sign: From the Sixteenth to the Twentieth Centuries. Translated by John Howe. Verso. ISBN 1859844022.
Ancient Chinese legend holds that a man named Lao Ai had the largest penis in history and that he had an affair with Queen Dowager Zhao (c. 280–228 BC), the mother of Qin Shi Huang, by pretending to be a eunuch. Ancient Koreans admired large penises and King Jijeung (437–514 AD) of the Silla Dynasty is said to have had a forty-five-centimeter penis that was so large his subordinates had to search for a woman that fit him. Traditional Japanese erotic paintings usually show genitals as exaggeratedly large. The oldest known painting of this type, found in the Hōryū-ji Temple in Ikaruga, dates to the eighth century AD and depicts a fairly large penis.
== Background == High performance liquid chromatography (HPLC) and electron ionization mass spectrometry (EIMS) are two analytical techniques that, in principle, seem to be incompatible. However, because these two approaches share a great deal of applications in the analysis of suitable molecules, typically less than 1000 u, a large effort has been devoted by the scientific community to develop a reliable, easy-to-use, and flawless interface. The first successful and commercially available device to combine EI and HPLC was designed by Willoughby and Browner in 1984. It was based on the conversion of the solute into a beam of particles, after the formation of spray droplets and the elimination of the solvent vapors through a multi-stage momentum separator. Although its efficient interfacing mechanism and a unique trait, particle beam performance was sometimes inadequate to an increasing number of new, demanding applications and was quickly replaced by a family of atmospheric pressure ionization-based interfaces (API) when they became commercially available. However, the possibility to record an EI spectrum from an HPLC application remained a challenge for a long time. The first Direct-EI prototype was first presented in 2002 and proposed an innovative approach that improved interfacing performance compared to that of particle beam and opened new opportunities for LC-MS applications.
== Treatment == Disease progression may be slowed with immunosuppressives and other medications, and esophageal reflux, pulmonary hypertension and Raynaud phenomenon may benefit from symptomatic treatment. However, there is no cure for this disease as there is no cure for scleroderma in general.
Sources: en.wikipedia.org
== Method == SISCAPA is an extension of the well-known gold-standard methods of stable-isotope dilution for quantitation of small molecules by mass spectrometry (MS). Rather than measure an intact protein directly by mass spectrometry, SISCAPA makes use of proteolytic digestion (e.g., with the enzyme trypsin) to cleave sample proteins into smaller peptides ideally suited to quantitation by mass spectrometry. By selecting a target peptide whose sequence occurs only in the selected target protein (a so-called “proteotypic” peptide), the target peptide can serve as a direct quantitative surrogate for the target protein (assuming the digestion process is complete, or at least reproducible). A synthetic version of the target peptide containing a stable isotope label is added in a known amount to the digested sample to serve as an internal standard (SIS). Since the target peptide and SIS are chemically indistinguishable throughout the workflow, but can be measured separately by a mass spectrometer due to the mass difference of the stable isotope label, their ratio provides the desired quantitative estimate of the target peptide amount. The SISCAPA workflow adds a specific enrichment step to the isotope dilution method in which a selected target peptide, together with its associated SIS internal standard, is captured by a sequence-specific anti-peptide antibody.
== Etymology and pronunciation == The word synovium is related to the word synovia in its sense meaning "synovial fluid". The latter was coined by Paracelsus. More information is given at Synovial fluid § Etymology and pronunciation.
In the gas phase: rocket engines The industrial synthesis such as ammonia in the Haber–Bosch process (depicted right) takes place through a succession of equilibrium steps including adsorption processes Atmospheric chemistry Seawater and other natural waters: chemical oceanography Distribution between two phases log D distribution coefficient: important for pharmaceuticals where lipophilicity is a significant property of a drug Liquid–liquid extraction, Ion exchange, Chromatography Solubility product Uptake and release of oxygen by hemoglobin in blood Acid–base equilibria: acid dissociation constant, hydrolysis, buffer solutions, indicators, acid–base homeostasis Metal–ligand complexation: sequestering agents, chelation therapy, MRI contrast reagents, Schlenk equilibrium Adduct formation: host–guest chemistry, supramolecular chemistry, molecular recognition, dinitrogen tetroxide In certain oscillating reactions, the approach to equilibrium is not asymptotically but in the form of a damped oscillation . The related Nernst equation in electrochemistry gives the difference in electrode potential as a function of redox concentrations. When molecules on each side of the equilibrium are able to further react irreversibly in secondary reactions, the final product ratio is determined according to the Curtin–Hammett principle. In these applications, terms such as stability constant, formation constant, binding constant, affinity constant, association constant and dissociation constant are used.
Sources: en.wikipedia.org
DNP raises energy expenditure by 30 to 40 percent and causes a weight loss of 0.7–0.9 kilograms (1.5–2.0 lb) per week. Although DNP is no longer in clinical use as a weight loss drug due to its dangerous side effects, its mechanism of action remains under investigation as a potential approach for treating obesity and non-alcoholic fatty liver disease. Researchers developed a prodrug, HU6, which is metabolized to DNP in the liver to provide more stable blood concentrations. HU6 completed a phase II trial in which it produced significant reductions in liver fat and body weight in overweight people with elevated liver fat, without serious adverse effects. DNP is used by bodybuilders, fitness enthusiasts, and people with an eating disorder to lose weight. The user profile is similar to that of anabolic steroids; many perceive it to be effective and with manageable risks. Despite health warnings from regulators, DNP is readily available online sometimes under other names such as Dinosan, Dnoc, Solfo Black, Nitrophen, Aldifen, and Chemox. DNP is often sold in tablets containing 100 to 200 mg and may be sold alongside other substances such as anabolic steroids and thyroxine. It may also be found as a contaminant in other bodybuilding supplements not advertised as containing DNP. Online message boards provide information on dosage and regimens for DNP use, and describe the risks of taking the compound and provide advice on how to mitigate hyperthermia. According to a study published in 2023, the most commonly reported doses were between 150 to 300 mg/d.
=== July === 1 July – Dennis Lattimer, muralist (born 1946). 2 July – Des Gorman, diving and hyperbaric medicine specialist (University of Auckland) and health bureaucrat (born 1953). 3 July Terry Brown, brothel owner (born 1956/1957). (death announced on this date) Hilary Stace, disability and autism advocate, eugenics researcher (born 1954) 5 July – Tim Bray, actor, comedian, and children's theatre founder (born 1964). 6 July – Kay Bradford, child and adolescent psychiatrist (born 1930). 9 July – Bruce Harris, legal academic (University of Otago, University of Auckland). 11 July Bert Brownlie, economist (University of Auckland, University of Canterbury) and university administrator, University of Canterbury vice-chancellor (1977–1998) (born 1932). Alex McNabb, mathematician (DSIR), Fellow of the Royal Society of New Zealand (since 1985) (born 1930). 12 July – Heather Roe, field hockey player (national team) (born 1939). 15 July – Neill Price, firefighter, local politician and community leader, Waimakariri District Councillor (1989–1998) (born 1936). 16 July Chris Faiumu, musician (Fat Freddy's Drop) and reggae-dub producer. Bruce McTavish, boxing referee (born 1940). Andrew Oliver, oldest person known to have survived with Fryns–Aftimos syndrome (born c. 1984). 17 July Barrie Downey, business executive (Fletcher Challenge) (born 1930). Don McIntosh, rugby union player (Wellington, national team) (born 1931). Greer Twiss, sculptor (Karangahape Rocks) and educator (University of Auckland), Arts Foundation of New Zealand Icon (since 2011) (born 1937).
Immunoaffinity chromatography uses the specific binding of an antibody-antigen to selectively purify the target protein. The procedure involves immobilizing a protein to a solid substrate (e.g. a porous bead or a membrane), which then selectively binds the target, while everything else flows through. The target protein can be eluted by changing the pH or the salinity. The immobilized ligand can be an antibody (such as immunoglobulin G) or it can be a protein (such as protein A). Because this method does not involve engineering in a tag, it can be used for proteins from natural sources.
== History == Progeria was first described in 1886 by Jonathan Hutchinson. It was also described independently in 1897 by Hastings Gilford. The condition was later named Hutchinson–Gilford progeria syndrome. Scientists are interested in progeria partly because it might reveal clues about the normal process of aging.
Sources: en.wikipedia.org
HPLC separates and detects individual compounds in a liquid sample, producing peaks at characteristic retention times. Peak area or height can be used to estimate concentration when calibrated with known standards. It does not identify unknown compounds with certainty unless additional detectors or reference materials are used.
Pressure drives the liquid mobile phase through a column packed with small particles. Without pressure, flow would be very slow or stop because the packed bed resists liquid movement. Modern pumps maintain a steady flow despite the resistance.
A chromatogram is a plot of detector signal against time after sample injection. Each peak represents a compound or group of compounds eluting from the column. Retention time and peak area are the main measurements read from the plot.
Validation establishes suitability for a new method, while verification confirms that a method works in a specific laboratory. Verification is often used when a validated method is adopted with existing equipment and staff. Both rely on documented acceptance criteria.