Everything below concerns data integrity. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-01-08. Where a claim depends on a specific study, the study is described rather than over-claimed.
Reversed-phase chromatography dominates modern HPLC testing, using a nonpolar stationary phase such as chemically bonded octadecyl groups and a polar mobile phase of water mixed with organic solvent. Analytes partition between the mobile and stationary phases according to hydrophobicity. Gradient elution changes the mobile phase composition over time to separate compounds with a wide range of retention. Isocratic elution keeps the composition constant and is simpler for routine assays. Column temperature, pH, and flow rate influence selectivity, peak shape, and retention time, so these parameters are controlled during a validated method.
Detection in HPLC testing commonly relies on ultraviolet-visible absorbance, fluorescence, refractive index, or mass spectrometry. A diode array detector records full spectra across a wavelength range, which helps identify co-eluting peaks. Mass spectrometry provides mass-to-charge ratios and can confirm molecular identity at low concentrations. The choice of detector depends on analyte structure, required sensitivity, and whether quantitation or identification is the goal. No single detector works for every compound, and method development often compares responses before selecting one.
High-performance liquid chromatography is an analytical technique that separates components of a liquid sample by passing it 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 interaction with the stationary phase cause analytes to migrate at different rates. Detectors record elution as peaks, and a data system converts signals into a chromatogram. The method is suited to compounds that dissolve in a liquid and are not volatile enough for gas chromatography.
Quality control samples are inserted at intervals to monitor accuracy and precision throughout a batch. Blank samples detect contamination, while spiked samples assess recovery from the sample matrix. Calibration standards establish the relationship between detector response and concentration, and control samples are prepared independently from them whenever possible. Laboratories also participate in proficiency testing and maintain audit trails, instrument logs, and reagent records. Ongoing review of control charts can reveal trends before they cause out-of-specification results.
Method validation demonstrates that an HPLC procedure is suitable for its intended purpose. Common validation parameters include accuracy, precision, specificity, linearity, range, limit of detection, limit of quantification, and robustness. Accuracy reflects agreement with a reference value, while precision describes repeatability under defined conditions. Specificity shows whether the method can measure the analyte in the presence of impurities or matrix components. Validation documents are reviewed before a method is used for routine testing or regulatory submissions.
| Property | Value | Notes |
|---|---|---|
| Separation mode | Reversed-phase | Most common for neutral and moderately polar analytes |
| Column particle size | 3–5 µm | Smaller particles improve resolution but raise backpressure |
| Mobile phase pH range | 2–8 | Silica-based columns may degrade outside this range |
| Typical flow rate | 1.0–2.0 mL/min | For analytical columns with 4.6 mm internal diameter |
| Common synonyms | HPLC, LC, high-pressure liquid chromatography | High-performance liquid chromatography is the standard expansion |
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.
Regulatory and pharmacopeial texts shape how HPLC testing is performed and documented. The International Council for Harmonisation provides validation guidance, while pharmacopeias publish general chromatography chapters and monographs for specific materials. Accreditation standards such as ISO/IEC 17025 address laboratory competence and traceability. Inspectors may review instrument qualification, analyst training, reference material control, and electronic records. Open questions include how best to validate methods for new complex products and how to handle automated data processing. Laboratories generally resolve these issues through risk assessment, method lifecycle management, and documented scientific justification.
Key performance measures include retention time, peak area, peak height, resolution, tailing factor, and plate count. Retention time helps identify a peak under fixed conditions, but confirmation often requires a second method or detector. Peak area and height relate to concentration through calibration curves, which may be linear or nonlinear depending on the detector response. Resolution describes separation between adjacent peaks, while tailing factor and plate count describe peak shape and column efficiency. Performance checks verify these values before and during a run to confirm that the instrument is performing within limits.
High-performance liquid chromatography testing separates components of a liquid sample by forcing a mobile phase through a packed column. The stationary phase inside the column interacts with analytes to different degrees, so each compound exits at a characteristic retention time. A pump delivers solvent at controlled flow and pressure, while an injector introduces a precise sample volume. Detectors such as ultraviolet-visible, fluorescence, refractive index, or mass spectrometric instruments record the separated bands. The resulting chromatogram provides qualitative and quantitative information about the mixture.
HPLC testing is not a single fixed procedure; it is a family of separation modes. Reversed-phase, normal-phase, ion-exchange, size-exclusion, and affinity chromatography each suit different analyte properties. Reversed-phase methods dominate because they handle many neutral and moderately polar compounds. Detection can be optical, electrochemical, or mass spectrometric, and the detector dictates what information is available. Coupling with mass spectrometry increases selectivity and enables identification when standards are unavailable. The technique cannot separate every mixture without adjustment.
HPLC testing is an analytical technique used to separate, identify, and quantify components in a liquid sample. It relies on a pressurized mobile phase that carries the sample through a column packed with stationary phase. Different compounds travel at different rates because of interactions with the stationary and mobile phases. The resulting signal versus time is a chromatogram. Peak position indicates identity under specified conditions, while peak area or height relates to amount.
==== Radio and podcasts ==== "Sink or Swim. Act Two. I'm Not a Doctor, But I Play One at the Holiday Inn.". This American Life. Episode 321. 1 December 2006. — A former heroin addict realizes that he wants to help other addicts kick their habits. The problem is, he wants to do this using a hallucinogenic drug – ibogaine – that is completely illegal, and which requires medical expertise he doesn't have. In January 2025, former Texas Governor Rick Perry and W. Bryan Hubbard, appeared on The Joe Rogan Experience. The trio discussed advances in public policy towards ibogaine and eventual FDA clinical trials. Hubbard was the former chairman and executive director of the Kentucky Opioid Abatement Advisory Commission until he was asked to resign in December 2023. Since 2024, Hubbard has continued his campaign outside Kentucky and now works with the REID Foundation as the executive director of the American Ibogaine Initiative.
Yeast extracts consist of the cell contents of yeast without the cell walls; they are used as food additives or flavorings, or as nutrients for bacterial culture media. They are often used to create savoury flavors and umami taste sensations and can be found in a large variety of packaged foods including frozen meals, crackers, snack foods, gravy, stock and more. They are rich in B vitamins (but not B12). Yeast extracts and fermented foods contain glutamic acid (free glutamates), an amino acid which adds an umami flavor. Glutamic acid is found in meat, cheese, fungi (mushrooms and yeast) and vegetables—such as broccoli and tomatoes. A number of other substances found in yeast extract provide aromas, some meat-like, when allowed to react under heat. The thermal process to make yeast extract of the autolysate type was invented in the 19th century by Justus von Liebig. Yeast cells are heated until they rupture, then the cells' own digestive enzymes combined with the intense heat help to break large proteins down into simpler compounds (amino acids and peptides), a process called autolysis. The insoluble cell walls are then separated by centrifuge, filtered, and usually spray-dried. This is the process used for spreads such as Vegemite and Marmite. Yeast extracts in liquid form can be dried to a light paste or a dry powder. This is not the same as nutritional yeast seasonings, which are made from lyophilized intact cells and consequently have a lighter flavor.
The enormous number of published literature makes it virtually impossible for individuals to read every paper, resulting in disjointed sub-fields of research. Literature analysis aims to employ computational and statistical linguistics to mine this growing library of text resources. For example:
== Later life and recognition == Smolková-Keulemansová became one of the leading experts in the field of chromatography. She was the first professor of chemistry in the Czech Republic and one of the first in Europe. Not only did she continue her studies in chemistry, but she also focused on polarography, a PhD focused on gas chromatography and a DrSc concentrated on inclusion compounds in chromatography. In the early 1970s, inclusion complex formations in selective analytical separations became a major focus of Smolková-Keulemansová's, her first choice being cyclodextrins, but moving on with urea and thiourea for the separation of isomers. Her research on cyclodextrins started soon after her methods focused on gas chromatography, high-performance liquid chromatography and electromigration. Her research became more widespread and she was asked to add many monographs on cyclodextrins, one of them being for a compendium on supramolecular chemistry edited by Jean-Marie Lehn. She has written and co-written 140 original papers and numerous reviews and has contributed to many books, including her work in Journal of High-Resolution Chromatography, "A Few Milestones on the Journey of Chromatography", and an article in the journal Chromatographia, "Study of retention of isomeric aromatic hydrocarbons on GTCB and cyclodextrins". Smolková-Keulemansová died on 27 February 2024, at the age of 96.
=== Preservation === Although current technology and methods have allowed for recreation and translation of many tablets, the vast majority of them remain illegible. Thus, to keep these tablets in prime shape for future analysis, efforts are being made to keep these artefacts preserved. Preservation included a combination of immersion in polyethylene glycol and freeze drying.
Sources: en.wikipedia.org
Banting's namesake, the Banting Research Foundation, was created in 1925 and provides funding to support health and biomedical research in Canada. Banting's name is immortalized in the yearly Banting Lectures, given by an expert in diabetes, and by the creation of the Banting and Best Department of Medical Research of the University of Toronto; Sir Frederick G Banting Research Centre located on Sir Frederick Banting Driveway in the Tunney's Pasture complex, Ottawa; Banting Memorial High School in Alliston Sir Frederick Banting Secondary School in London, Ontario; Sir Frederick Banting Alternative Program Site in Ottawa; Frederick Banting Elementary School in Montréal-Nord and École Banting Middle School in Coquitlam. The "Major Sir Frederick Banting, MC, RCAMC Award for Military Health Research", sponsored by the True Patriot Love Foundation, is awarded annually by the Surgeon General to the researcher whose work presented at the annual Military and Veterans Health Research Forum is deemed to contribute most to military health. It was first awarded in 2011 in the presence of several Banting descendants. The "Canadian Forces Major Sir Frederick Banting Term Chair in Military Trauma Research" at Sunnybrook Health Sciences Centre was established in 2012. The first Chair holder is Colonel Homer Tien, medical director of Sunnybrook's Tory Regional Trauma Centre and Senior Specialist and Trauma Adviser to the Surgeon General.
The first pathway (see the reaction illustrated below) involves the deamination of histamine by the enzyme diamine oxidase to form imidazole acetaldehyde. In the second pathway, histamine is metabolized into Nτ-methylhistamine (also known as 1-methylhistamine), which also has some biological activity, albeit much weaker than that of histamine. Still, NMT, being a product in a reaction catalyzed by HNMT, may inhibit expression of HNMT in a negative feedback loop. This reaction is Nτ-methylation of histamine by the histamine N-methyltransferase (HNMT) enzyme. The Nτ-methylhistamine, unless excreted by the kindney, is subsequently oxidized into Nτ-methylimidazoleacetic acid (Nτ-MIAA) by the enzyme monoamine oxidase (MAO). This two-step process reduces the activity of histamine in the body and is important for quick deactivation of histamine in the brain. The third pathway is found exclusively in enterobacteria and has not been identified in mammals. This pathway involves the acetylation of histamine by an acetylase to form 4-(-acetylaminoethyl)imidazole. DAO catalyzes the oxidative deamination of polyamines, such as histamine and putrescine, to produce aminoaldehydes, hydrogen peroxide, and ammonia.
Some academics, such as Stéphane Courtois (The Black Book of Communism), Steven Rosefielde (Red Holocaust), and Rudolph Rummel (Death by Government), wrote of mass, excess deaths under Marxist–Leninist regimes. These authors defined the political repression by communists as a "Communist democide", "Communist genocide", "Red Holocaust", or followed the "victims of Communism" narrative. Some of them compared Communism to Nazism and described deaths under Marxist–Leninist regimes (civil wars, deportations, famines, repressions, and wars) as being a direct consequence of Marxism–Leninism. Some of these works, in particular The Black Book of Communism and its 93 or 100 millions figure, are cited by political groups and Members of the European Parliament. Without denying the tragedy of the events, other scholars criticise the interpretation that sees communism as the main culprit as presenting a biased or exaggerated anti-communist narrative. Several academics propose a more nuanced analysis of Marxist–Leninist rule, stating that anti-communist narratives have exaggerated the extent of political repression and censorship in communist states and drawn comparisons with what they see as atrocities that were perpetrated by capitalist countries, particularly during the Cold War. These academics include Mark Aarons, Noam Chomsky, Jodi Dean, Kristen Ghodsee, Seumas Milne, and Michael Parenti. Ghodsee, Nathan J.
Renin (etymology and pronunciation), also known as an angiotensinogenase, is an aspartic protease protein and enzyme secreted by the kidneys that participates in the body's renin–angiotensin–aldosterone system (RAAS), which increases the volume of extracellular fluid (blood plasma, lymph, and interstitial fluid) and causes arterial vasoconstriction. Thus, it increases the body's mean arterial blood pressure. Renin is not commonly referred to as a hormone, although it has a receptor, the (pro)renin receptor, also known as the renin receptor and prorenin receptor (see also below), as well as enzymatic activity with which it hydrolyzes angiotensinogen to angiotensin I.
Sources: en.wikipedia.org
HPLC testing separates and quantifies components in a liquid sample. It is used to check identity, purity, concentration, or stability. The technique works best for compounds that dissolve and are not easily vaporized.
The pump maintains a steady flow rate and pressure, which keeps retention times reproducible. Pulsation or flow errors can shift peaks and distort quantitation. Modern pumps use feedback control to reduce these variations.
HPLC alone usually separates compounds but does not always identify them. Retention time matching with a known standard provides tentative identification. Coupling HPLC to mass spectrometry adds mass information that supports structural identification.
Method validation is the documented process of showing that an HPLC procedure produces reliable results for a defined purpose. It examines parameters such as accuracy, precision, specificity, linearity, and robustness. Regulators and quality systems often require validation before routine use.