The short version of Stationary phase fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2025-12-25. Anything still debated is marked as such rather than presented as settled.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Separation mode | Reversed-phase | Common for polar and moderately polar analytes |
| Typical column length | 100-250 mm | Shorter columns can reduce run time |
| Particle size | 3-5 micrometers | Smaller particles improve efficiency but raise pressure |
| Flow rate | 0.5-2.0 mL/min | Depends on column dimensions and pressure limits |
| Detection | UV-Vis absorbance | Widely used for compounds with chromophores |
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.
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.
Laboratories apply HPLC testing across pharmaceutical, food, environmental, and industrial chemistry. The method can measure active ingredients, impurities, additives, preservatives, and degradation products. Sample preparation often includes dilution, filtration, and sometimes extraction or derivatization. The choice of column, mobile phase, pH, temperature, and detector depends on the analytes and matrix. Results are compared with reference standards to assign identity and concentration. Method suitability is judged by resolution, precision, and accuracy.
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.
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.
System suitability testing is performed before and during analytical runs to confirm that the instrument and method are working as expected. Typical checks include retention time, peak area precision, resolution between critical pairs, tailing factor, and theoretical plate count. Acceptance criteria are set in the method or pharmacopeial monograph. If a suitability check fails, the run may be rejected and the instrument or sample preparation may need investigation. This practice helps prevent release of data from a system that has drifted out of control.
Several phase 1 clinical trials have been performed by experts in the field of adoptive immunotherapy of cancer. Hans Klingemann and Sally Arai completed a US trial at Rush University Medical Center (Chicago) in renal cell cancer and melanoma patients in 2008, and Torsten Tonn, MD and Oliver Ottmann, MD completed the European trial at the University of Frankfurt in patients with various solid and hematological malignancies in 2013. Armand Keating at Princess Margaret Hospital in Toronto conducted a trial in which NK-92 cells were given to patients who had relapsed after autologous bone marrow transplants for leukemia or lymphoma. In all clinical trials so far, NK-92 cells were administered as a simple intravenous infusion, dosed two or three times per treatment course, and given in the outpatient setting. Of the 39 patients enrolled across the three studies, 2 serious (grade 3–4) side-effects occurred during or after the infusion of NK-92 cells, the side effects disappeared afterward. The doses given to patients ranged from 1 × 108 cells/m2 to 1 × 1010 cells/m2 per infusion. Patients received between two and three infusions over a period of less than a week. About one-third of the treated patients had clinically meaningful responses with some of them fully recovering.
=== 1994 Tammiku, Estonia === The 1994 Tammiku incident involved the theft of radioactive material from a nuclear waste storage facility in Männiku, Saku Parish, Harju County, Estonia. Three brothers, unaware of the facility's nature, broke into a shed while scavenging for scrap metal. One of the brothers received a 4000 rad (40 Gy) whole-body dose from a caesium-137 source that had been released from a damaged container, succumbing to radiation poisoning 12 days later.
18 October 2016: Astellas completes a clinical trial for Type-2 diabetes mellitus in Japan prior to October 2016 7 September 2016: Astellas Pharma plans a phase III trial for Type-1 diabetes mellitus (Combination therapy) in Japan 1 August 2016: Phase III clinical trials in type 1 diabetes mellitus (combination therapy) in Japan Ipragliflozin was also in development for type 2 diabetes mellitus in the U.S., Europe and other countries, and three phase II trials were completed in combination with metformin. This was since discontinued.
====== Fatty acid ethoxylates ====== Fatty acid ethoxylates are a class of very versatile surfactants, which combine in a single molecule the characteristic of a weakly anionic, pH-responsive head group with the presence of stabilizing and temperature responsive ethyleneoxide units.
In 1996, Vaynshtejn was probably the first to prove another beautiful characterization of tangential quadrilaterals, that has later appeared in several magazines and websites. It states that when a convex quadrilateral is divided into four nonoverlapping triangles by its two diagonals, then the incenters of the four triangles are concyclic if and only if the quadrilateral is tangential. In fact, the incenters form an orthodiagonal cyclic quadrilateral. A related result is that the incircles can be exchanged for the excircles to the same triangles (tangent to the sides of the quadrilateral and the extensions of its diagonals). Thus a convex quadrilateral is tangential if and only if the excenters in these four excircles are the vertices of a cyclic quadrilateral. A convex quadrilateral ABCD, with diagonals intersecting at P, is tangential if and only if the four excenters in triangles APB, BPC, CPD, and DPA opposite the vertices B and D are concyclic. If Ra, Rb, Rc, and Rd are the exradii in the triangles APB, BPC, CPD, and DPA respectively opposite the vertices B and D, then another condition is that the quadrilateral is tangential if and only if
Sources: en.wikipedia.org
== How it works == This method relies on phase separation by centrifugation of a mixture of the aqueous sample and a solution containing water-saturated phenol and chloroform, resulting in an upper aqueous phase and a lower organic phase (mainly phenol). Guanidinium thiocyanate, a chaotropic agent, is added to the organic phase to aid in the denaturation of proteins (such as those that strongly bind nucleic acids or those that degrade RNA). The nucleic acids (RNA and/or DNA) partition into the aqueous phase, while protein partitions into the organic phase. The pH of the mixture determines which nucleic acids get purified. Under acidic conditions (pH 4-6), DNA partitions into the organic phase while RNA remains in the aqueous phase. Under neutral conditions (pH 7-8), both DNA and RNA partition into the aqueous phase. In a last step, the nucleic acids are recovered from the aqueous phase by precipitation with 2-propanol. The 2-propanol is then washed with ethanol and the pellet briefly air-dried and dissolved in TE buffer or RNAse free water. Guanidinium thiocyanate denatures proteins, including RNases, and separates rRNA from ribosomal proteins, while phenol, isopropanol and water are solvents with poor solubility. In the presence of chloroform or BCP (bromochloropropane), these solvents separate entirely into two phases that are recognized by their color: a clear, upper aqueous phase (containing the nucleic acids) and a lower phase (containing the proteins dissolved in phenol and the lipids dissolved in chloroform).
where "ads" stands for "adsorbed", "m" stands for "monolayer equivalence" and "vap" is reference to the vapor pressure of the liquid adsorptive at the same temperature as the solid sample. The unit function creates the definition of the molar energy of adsorption for the first adsorbed molecule by:
=== 5 April === Ukraine launched a barrage of drones into western Russia, targeting four airbases. Ukrainian officials claim at least six military aircraft were destroyed, eight others were "heavily damaged", and at least 20 personnel were killed or injured at a military airbase near Morozovsk, Rostov Oblast. Security sources reported the airbase held Su-27 and Su-34 aircraft, while an open-source intelligence researcher reported the base also held three Su-35 aircraft. Rostov Oblast Governor Vasily Golubev claimed Russia intercepted 44 Ukrainian drones and that only a 16-storey residential block and power substation were damaged, leaving around 600 people without power. Eight people were later injured by one of the fallen drone's explosives detonating during an investigation of the site. Drones were also launched at Engels-2 airbase in Saratov Oblast, reportedly home to Tu-95 and Tu-22 bombers. The attack allegedly caused "serious damage" to three Tu-95MS bombers and resulted in the deaths of seven. One drone was shot down over the nearby town of Engels. There were no reports of casualties or infrastructure damage from the neutralized drone. Yeysk Airport, which hosts the aviation units of the 4th Army of the Russian Air Force, was also allegedly struck, with four Russians killed and two Su-25 aircraft destroyed. Local official Roman Bublik denied any damage. Kursk Vostochny Airport was also targeted. There was no information provided on possible damage. Russia reported no casualties and denied any serious damage, claiming to have intercepted 53 drones.
Omics.org Archived 2014-01-02 at the Wayback Machine Omics terms and concepts home page. Probably the first omics web page created. List of omics Archived 2015-07-09 at the Wayback Machine, including references/origins. Maintained by the (CHI) Cambridge Health Institute.
does not tell us whether or not the spreading will speed up or slow down in the latter stages when the fraction of susceptible people in the community has dropped significantly after recovery or vaccination.
Sources: en.wikipedia.org
Health Minister Simeon Brown confirms the Government would lower the bowel screening eligibility age range from 60 to 58 years, using funding from a cancelled pilot programme established by the previous Labour government to lower the eligibility age for Māori and Pasifika New Zealanders from 60 to 50 years. Air New Zealand CEO Greg Foran announces that he will resign from his position effective 20 October. 7 March: New Zealand Labour Party leader Chris Hipkins announces a cabinet reshuffle of his shadow cabinet during his State of the Nation speech. Health Minister Simeon Brown announces a major overhaul of Health New Zealand including reinstating its leadership board, decentralisation and promoting private-public partnership. 8 March: A Pride parade is held in Wellington, with Mayor of Wellington Tory Whanau and actor Karen O'Leary attending. About 30 Destiny Church Man Up protesters stage a counter-protest. Police separate the two groups. A total fire ban comes into force in the Northland Region from 12am midnight in response to persistent dry, hot and windy conditions. 11 March – School lunch provider Libelle Group goes into liquidation, affecting 500 staff. The company had been contracted by the Compass Group to provide 125,000 meals to the Government's "Ka Ora, Ka Ako" school meal programme. 12 March: Camilla Belich's Crimes (Theft By Employer) Amendment Bill passes its third reading in Parliament with the support of the Labour, Green, Te Pāti Māori and New Zealand First.
== System components == A typical laboratory FPLC consist of one or two high-precision pumps, a control unit, a column, a detection system and a fraction collector. Although it is possible to operate the system manually, the components are normally linked to a personal computer or, in older units, a microcontroller.
== D == dalton – Darwinian fitness – Darwinism – decomposer – dehydrogenase – deletion – denaturation – dendrite – dengue – denitrification – deoxyribonucleic acid – deoxyribose – depolarization – desmosome – deuterostome – diabetes mellitus – diastole – diffusion – digestion – dihybrid cross – dikaryon – dikaryotic – disaccharide – DNA ligase – DNA methylation – DNA polymerase – double circulation – double helix – Down syndrome – drupe – duodenum – dynein
Tinidazole, sold under the brand name Tindamax among others, is a medication used against infections caused by certain anaerobic bacteria and protozoa. It was developed in 1972 and is a prominent member of the nitroimidazole antibiotic class. Tinidazole is a therapeutic alternative on the World Health Organization's List of Essential Medicines.
Sources: en.wikipedia.org
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.
Performance checks confirm that the chromatographic system works within preset limits before results are accepted. They examine factors such as peak resolution, tailing, and repeatability. If criteria fail, the run may need correction or repetition.
Retention time alone is not definitive proof because other compounds can elute at similar times. Confirmation usually uses a second method, a different column, or a detector such as mass spectrometry. Authentic standards strengthen identification.
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.