stationary phase is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Updated 2025-12-19. Numbers and descriptions here follow the published literature rather than marketing material.
Developing an HPLC method begins with defining the purpose, such as quantifying a main component, measuring impurities, or confirming identity. Analysts select separation mode, column, mobile phase, detection, and sample preparation based on analyte properties and matrix. Experiments vary solvent strength, pH, buffer type, and temperature to achieve resolution between critical peaks. The goal is a robust method that produces reliable results across instruments and operators. Method development often involves trial runs and statistical optimization.
Validation demonstrates that a method is suitable for its intended use. Typical performance characteristics include accuracy, precision, specificity, linearity, range, limit of detection, limit of quantitation, and robustness. Regulators and standards organizations provide frameworks, but specific requirements depend on the application and jurisdiction. System suitability tests are run before sample analysis to confirm resolution, peak symmetry, retention time repeatability, and sensitivity. A validated method is not permanently fixed; changes may require partial or full revalidation.
Separation modes differ by the chemistry of the stationary phase and the composition of the mobile phase. Reversed-phase testing uses a nonpolar column and polar solvents, making it common for pharmaceutical, environmental, and food analytes. Normal-phase testing uses a polar column and nonpolar solvents for compounds that are poorly retained in reversed-phase systems. Ion-exchange and ion-pair methods separate charged species, while size-exclusion methods sort molecules by hydrodynamic volume. Gradient elution changes solvent strength over time to resolve complex mixtures, and isocratic elution holds solvent composition constant for simpler assays.
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.
| Property | Value | Notes |
|---|---|---|
| Validation parameter | Accuracy | Closeness of measured value to accepted reference value |
| Validation parameter | Precision | Agreement among repeated measurements under specified conditions |
| System suitability check | Resolution ≥ 1.5 | Baseline separation between critical peak pair |
| System suitability check | Tailing factor ≤ 2.0 | Common target for peak symmetry |
| Documentation | Validation report | Summarizes experiments, acceptance criteria, and conclusions |
Detection in HPLC testing commonly relies on ultraviolet-visible absorbance, fluorescence, refractive index, or mass spectrometry. UV detection is widely used because many organic compounds absorb light, but it requires a chromophore. Mass spectrometry provides mass-based identification and high sensitivity for trace analytes. Each detector has trade-offs in selectivity, cost, and compatibility with mobile phases. Quantification typically uses calibration curves prepared from reference standards. Results are reported as concentration, purity, or presence above a limit.
HPLC testing separates dissolved compounds by passing a liquid sample through a column packed with stationary phase. A pump delivers mobile phase at controlled flow, and the sample components interact differently with stationary and mobile phases. Compounds that spend more time in mobile phase elute earlier; those retained by stationary phase elute later. Detectors record elution as peaks, and peak area or height relates to amount. This mechanism underpins quantitative analysis of mixtures.
Most routine HPLC testing uses reversed-phase columns, where the stationary phase is nonpolar and the mobile phase is a polar mixture such as water with an organic solvent. Analytes partition between the two phases according to polarity, size, and charge. Gradients that change solvent composition over time can separate compounds with broad retention ranges. Isocratic conditions keep solvent composition constant and suit simpler mixtures. The choice of column chemistry, pH, and temperature affects selectivity and peak shape.
Routine quality control monitors retention time shifts, baseline noise, system pressure, and peak shape. Trends can reveal column aging, mobile phase preparation errors, detector drift, or sample degradation. Corrective actions may include replacing the column, preparing fresh mobile phase, or recalibrating the detector. Stability testing often uses HPLC to measure parent compound loss and degradation product formation. Open questions remain about how accelerated stability results extrapolate to long-term storage under varied conditions.
Quality control for HPLC testing combines scheduled checks, documented procedures, and review of results. Before sample analysis, system suitability testing confirms that the instrument, column, and method meet predefined criteria. Common criteria include resolution between critical peaks, retention time precision, peak tailing, and theoretical plate count. Failure triggers investigation before results are reported. Records link raw data, calculations, instrument logs, and analyst identity to each batch, supporting audits and repeat analysis.
=== Honors === "10 Best Books of 2022" by The Washington Post "10 Best Books of 2022" by The New York Times. It is listed #61 on The New York Times' 100 Best Books of the 21st Century list Note: The novel was ranked #1 in its Reader's Picks List
== Awards and honors == 2024 York U Alumni Award for Outstanding Achievement 2020 Lifetime Achievement Award in Plasma Spectrochemistry 2019 HUPO Award (Human Proteome Organization) 2014 Fellow of the American Institute for Medical and Biological Engineering 2011 University of Toronto Inventor of the Year Award for Biomedical and Life Sciences 2011 Thermo Fisher Scientific Spectroscopy Award 2004 Elsevier / Spectrochimica Acta Atomic Spectroscopy Award for the most important paper published in Spectrochimica Acta Part B in 2002 (Title: Reaction cells and collision cells for ICP-MS: a tutorial review) in co-authorship with Dmitry Bandura and Vladimir Baranov 2003 W.A.E. McBryde medal from the Canadian Chemical Society of the Chemical Institute of Canada 2001 Manning Innovation Award, Award of Distinction Dr. Scott Tanner, together with Dr. Vladimir Baranov, received the Manning Award of Distinction from the Manning Innovation Awards Foundation for the remarkable invention of the ICP-MS Dynamic Reaction Cell (Collision/reaction cell). 1999 Pittcon Editors' Awards Perkin-Elmer Sciex for their ELAN 6100 DRC (Dynamic Reaction Cell) ICP-MS system. Fellow of the Royal Society of Chemistry (UK) Fellow of the American Institute for Medical and Biological Engineering (AIMBE)
== Medical uses == Clascoterone is indicated for the topical treatment of acne vulgaris in people aged twelve years of age and older. Two large phase III randomized controlled trials evaluated the effectiveness of clascoterone for the treatment of acne over a period of 12 weeks. Clascoterone decreased acne symptoms by about 8 to 18% more than placebo. The defined treatment success endpoint was achieved in about 18 to 20% of individuals with clascoterone relative to about 7 to 9% of individuals with placebo. The comparative effectiveness of clascoterone between males and females was not described.
Imogen Heap – vocals, production, mixing, engineering, programming Ashwin Srinivasan – background vocals (track 6), flute (track 6) Leo Abrahams – electric guitar (tracks 2, 6) David Daniels—electric guitar (track 6) Oli Langford – violin (tracks 2, 6, 9–10, 12–13) Ian Burdge – cello (tracks 6, 8, 10, 12–13) Richie Mills – drums (tracks 6, 9) Arve Henriksen – trumpet (tracks 8, 13) Simon Heyworth – mastering
Sources: en.wikipedia.org
== External links == IUPHAR GPCR Database and Ion Channels Compendium Archived 2019-03-23 at the Wayback Machine Human plasma membrane receptome Archived 2019-09-15 at the Wayback Machine Cell+surface+receptors at the U.S. National Library of Medicine Medical Subject Headings (MeSH)
It is thought to cause the majority of excess thyroid cancers seen after nuclear fission contamination (such as bomb fallout or severe nuclear reactor accidents like the Chernobyl disaster) However, these epidemiological effects are seen primarily in children, and treatment of adults and children with therapeutic 131I, and epidemiology of adults exposed to low-dose 131I has not demonstrated carcinogenicity.
== Monitoring == Especially in the early stages of feminizing hormone therapy, blood work is done frequently to assess hormone levels and liver function. The Endocrine Society recommends that patients have blood tests every three months in the first year of HRT for estradiol and testosterone, and that spironolactone, if used, be monitored every two to three months in the first year. Recommended ranges for total estradiol and total testosterone levels include but are not limited to the following:
Dean Paul Martin became a tennis player, actor and a captain in the California Air National Guard. He was married to actress Olivia Hussey and figure skater Dorothy Hamill, and was killed while piloting an F-4 Phantom jet in 1987. In 1996, Sundazed Music released The Rebel Kind: The Best of Dino, Desi & Billy, in which all of the group's singles and other non-cover material was collected for the first time on one album. From 1998 to 2010, a reconfiguration of the group, known as "Ricci, Desi, & Billy", performed at various times, in addition to releasing two live albums. The band performed new material and the original hits, with Ricci Martin, the youngest son of singer Dean Martin, replacing his late older brother, Dean Paul Martin. Billy Hinsche died of lung cancer on November 20, 2021, after a short illness. His mother, Celia Hinsche, also died on the same day.
=== Mauveine === Mauveine was discovered when Henry Perkin was trying to convert an artificial base into the natural alkaloid quinine. He tried adding aniline – a different base with a simpler construction. This created a black product. After purification, drying and washing with alcohol, Perkin had a mauve dye. Perkin filed his patent in August 1856 and a new dye industry was born. He at first called his discovery Tyrian Purple evoking the value of the ancient, highly expensive, pigment. Other names include aniline purple and Perkin's mauve. Rather than one homogenous molecule, the original mauvine was primarily a mix of four major compounds, mauveine A, mauveine B, mauveine C, and mauveine B2, although there were other mauvine and pseudo mauveines in the dye product.
Sources: en.wikipedia.org
It is a set of checks performed before or during an HPLC run to confirm the system works as expected. Parameters may include resolution, tailing factor, theoretical plates, and retention time precision. Failure can trigger maintenance, method adjustment, or repeat analysis.
Validation follows a planned protocol that tests accuracy, precision, specificity, linearity, range, detection limits, quantitation limits, and robustness. Results are compared against predefined acceptance criteria. The validation report supports regulatory filing or routine use.
Revalidation may be needed after changes to column chemistry, mobile phase, detection, sample preparation, or instrument type. It can also follow a pattern of out-of-specification results. The scope depends on whether the change affects method performance.
It measures the amounts and identities of compounds in liquid samples by separation and detection. Depending on the detector and reference standards, results can be qualitative or quantitative. The technique is used in fields such as pharmaceutical analysis, food safety, and environmental monitoring.