The short version of HPLC fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2026-08-01 and is reviewed periodically as new material appears.
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.
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.
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.
Method validation evaluates accuracy, precision, specificity, linearity, range, detection limit, quantitation limit, and robustness. Regulatory guidance for pharmaceuticals, foods, and environmental testing defines expected documentation and acceptance criteria. Verification confirms that a validated method works in a specific laboratory with its own instruments and reagents. Calibration curves use reference standards with known purity and traceability, while measurement uncertainty is estimated from validation data, control charts, and collaborative studies. The scope of validation depends on the method's intended use.
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.
| Property | Value | Notes |
|---|---|---|
| Separation mode | Reversed-phase | Nonpolar stationary phase with polar mobile phase |
| Typical column particle size | 3–5 µm | Smaller particles improve resolution but raise pressure |
| Typical flow rate | 0.5–2.0 mL/min | Depends on column dimensions and pressure limits |
| Common detection | UV-Vis absorbance | Requires analytes with chromophores |
| Typical run time | 5–30 min | Varies with method, gradient, and sample complexity |
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.
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.
High-performance liquid chromatography, or HPLC, separates dissolved compounds by passing a liquid mobile phase through a packed column. Components distribute differently between the stationary phase and the moving liquid, so they travel at different speeds and exit at different times. A detector records these eluting bands as peaks, and peak area or height relates to amount. The technique supports testing in pharmaceuticals, foods, environmental samples, and industrial chemicals. Quantification usually depends on calibration with known standards.
Several separation modes exist, including reversed-phase, normal-phase, ion-exchange, size-exclusion, and hydrophilic interaction liquid chromatography. Reversed-phase uses a nonpolar stationary phase with a polar mobile phase and is widely applied to small organic molecules. Gradient elution changes mobile phase composition during the run, while isocratic elution keeps it constant. Column chemistry, particle size, temperature, flow rate, and mobile phase pH all influence retention and resolution. Method development selects conditions that separate analytes from matrix components and from each other.
High-performance liquid chromatography is an analytical technique that separates components in a liquid sample. A pump moves a liquid mobile phase through a column packed with a solid stationary phase. Compounds interact differently with both phases and travel at different rates, leaving the column at distinct retention times. A detector records these arrivals as peaks on a chromatogram. The resulting pattern supports identification and quantification of substances in mixtures. Modern instruments use high pressure to force solvent through small particles, which improves speed and resolution compared with older low-pressure liquid chromatography methods.
Separation in HPLC depends on the chemistry of the stationary phase, the composition of the mobile phase, and the physical properties of the column. Reverse-phase separations use a nonpolar stationary phase and a polar mobile phase, and they are common for many organic compounds. Ion-exchange, size-exclusion, and normal-phase modes serve other classes of analytes. Gradient elution changes solvent strength over time, while isocratic elution holds it constant. Flow rate, temperature, particle size, and column length all influence peak shape and resolution. Detection may use ultraviolet absorbance, fluorescence, refractive index, or mass spectrometry, depending on the analyte and the required sensitivity.
== History == In 1989, work by the groups of Joseph T. Coyle and Ronald Schnaar showed in a neuronal cell line that excess exposure to glutamate or lowered cystine causes a decrease in glutathione levels, an accumulation in intracellular peroxides, and cytotoxicity. Later work by Pamela Maher and David Schubert noted the distinction of this cell death process from apoptosis, describing it as oxidative glutamate toxicity or oxytosis. In 2012, a study by Brent Stockwell and Scott Dixon characterized the iron dependence of this cell death process and coined the term ferroptosis. Oxytosis and ferroptosis are now thought to be the same cell death mechanism. Other early studies regarding the connection between iron and lipid peroxidation, cystine deprivation and oxidative cell death, the activity and importance of glutathione peroxidase 4 (GPX4), and the identification of small molecules that induce ferroptosis were key to the eventual characterization of ferroptosis.
== Medical uses == Lebrikizumab is indicated for the treatment of moderate-to-severe atopic dermatitis in adults and adolescents aged twelve years of age and older with a body weight of at least 40 kilograms (88 lb) who are candidates for systemic therapy.
In 1999, the Institute of Medicine published the Safety of Silicone Breast Implants (1999) study that reported no evidence that saline-filled and silicone-gel filled breast implant devices caused systemic health problems; that their use posed no new health or safety risks; and that local complications are "the primary safety issue with silicone breast implants", in distinguishing among routine and local medical complications and systemic health concerns." In 2000, the FDA approved saline breast implant Premarket Approval Applications (PMA) containing the type and rate data of the local medical complications experienced by the breast surgery patients. "Despite complications experienced by some women, the majority of those women still in the Inamed Corporation and Mentor Corporation studies, after three years, reported being satisfied with their implants." The premarket approvals were granted for breast augmentation, for women at least 18 years old, and for women requiring breast reconstruction. In 2006, for the Inamed Corporation and for the Mentor Corporation, the U.S. Food and Drug Administration lifted its restrictions against using silicone-gel breast implants for breast reconstruction and for augmentation mammoplasty. Yet, the approval was conditional upon accepting FDA monitoring, the completion of 10-year-mark studies of the women who already had the breast implants, and the completion of a second, 10-year-mark study of the safety of the breast implants in 40,000 other women.
Sources: en.wikipedia.org
Many factors must be considered with intracerebroventricular injection to maintain safety. Some of these factors include osmolarity, pH, volume, and the presence of preservatives in the drug solution. Also, intracranial pressure, cerebrospinal fluid bulk flow rate, and buffering capacity have an impact on the distribution and safety of the injected drug. A major concern of ICV injection is neurovascular injury and intracranial hemorrhage. The risk of these conditions increases with each additional injection or "tap". For this reason, if repeated taps are needed, a catheter-based device can be implanted. These devices are connected to a subcutaneous reservoir, the most common being the Ommaya reservoir. This can be accessed multiple times, with a sterile puncture through the scalp into the reservoir. There is also an associated risk of infection with this method, but it is less likely than other methods of accessing the intraventricular space. Other rare complications with this method include leukoencephalopathy, white matter necrosis, and intracerebral hemorrhage. Other complications can occur with this procedure, and they can be divided into infectious and noninfectious categories. Of the noninfectious complications, the most frequently reported were CSF leaks, hemorrhage, catheter malposition, catheter obstruction, and device malfunction. In one study, the most likely cause for device removals was due to infectious complications (73.75 percent). Of the infections, the most common cause was skin flora.
== Genome == An. gambiae s.s. genomes have been sequenced three times, once for the M strain, once for the S strain, and once for a hybrid strain. Currently, ~90 miRNA have been predicted in the literature (38 miRNA officially listed in miRBase) for An. gambiae s.s. based upon conserved sequences to miRNA found in Drosophila. Holt et al., 2002 and Neafsey et al., 2016 find transposable elements to be ~13% of the genome, similar to Drosophila melanogaster (also in Diptera). However they find the proportion of TE types to be very different from D. melanogaster with approximately the same composition of long terminal repeat retrotransposons, non-long terminal repeat retrotransposons and DNA transposons. These proportions are believed to be representative of the genus. The genetics and genomics of sex chromosomes have been discovered and studied by Windbichler et al., 2007 and Galizi et al., 2014 (a Physarum polycephalum homing endonuclease which destroys X chromosomes), Windbichler et al., 2008 and Hammond et al., 2016 (methods to reduce the female population), Windbichler et al., 2011 (trans from yeast), Bernardini et al., 2014 (a method to increase the male population), Kyrou et al., 2018 (a female necessary exon and a homing endonuclease to drive it), Taxiarchi et al., 2019 (sex chromosome dynamics in general) and Simoni et al., 2020 (an X chromosome destroying site specific nuclease). See § Gene drive below for their applications. An. gambiae has a high degree of polymorphism.
When the United States Navy ended Japan's Sakoku policy, and thus its isolation, the latter found itself defenseless against military pressures and economic exploitation by the Western powers. For Japan to emerge from the feudal period, it had to avoid the colonial fate of other Asian countries by establishing genuine national independence and equality. Following the María Luz Incident, Japan released the Chinese coolies from a western ship in 1872, after which the Qing imperial government of China gave thanks to Japan. However, tension soon rose between Qing China and Meiji Japan as a result of geopolitical tug-of-war for control and influence over the strategically vital Korean Peninsula. In 1884, pro-Japanese reformers in Korea, whom admired the successes of the Meiji Restoration and wanted to get rid of Korea's traditional subservience to an already weakened China after the Opium Wars, staged a brief coup d'état which triggered a clash with Qing troops stationed in Seoul who intervened to rescue the Korean king. In 1885, both nations signed an agreement to withdraw their troops from Korea and agreed to notify one another before sending military forces to the peninsula in the future. Tensions flared further in 1894 when Kim Ok-kyun, the pro-Japanese leader of the 1884 coup, was lured to Shanghai and assassinated, allegedly by Qing agents. The Japanese public was outraged, viewing this as a direct affront. At the same time, a massive peasant uprising broke out in Korea and the Korean king requested military aid from the Qing government to disperse the rebels.
Sources: en.wikipedia.org
The primary function of the breasts, as mammary glands, is the nourishing of an infant with breast milk. Milk is produced in milk-secreting cells in the alveoli. When the breasts are stimulated by the suckling of her baby, the mother's brain secretes oxytocin. High levels of oxytocin trigger the contraction of muscle cells surrounding the alveoli, causing milk to flow along the ducts that connect the alveoli to the nipple. Full-term newborns have an instinct and a need to suck on a nipple, and breastfed babies nurse for both nutrition and for comfort. Breast milk provides all necessary nutrients for the first six months of life, and then remains an important source of nutrition, alongside solid foods, until at least one or two years of age.
MDMA - Isomer Design MDMA - PsychonautWiki MDMA - Erowid MDMA - PiHKAL - Erowid MDMA - PiHKAL - Isomer Design A Multi-Site Phase 3 Study of MDMA-Assisted Therapy for PTSD (MAPP2) "MDMA Facts and Statistics". National Institute on Drug Abuse. 15 June 2020.
== Destaining == Proteins which were separated by 1D or 2D PAGE are usually visualised by staining with dyes like Coomassie brilliant blue (CBB) or silver. Although the sensitivity of the method is significantly lower, the use of Coomassie is more common for samples destined for mass spectrometry since the silver staining impairs the analysis. After excision of the protein band of interest from the gel most protocols require a destaining of the proteins before proceeding. The destaining solution for CBB contains usually the buffer salt ammonium bicarbonate (NH4HCO3) and a fraction of 30%-50% organic solvent (mostly acetonitrile). The hydrophobic interactions between protein and CBB are reduced by the organic fraction of the solution. At the same time, the ionic part of the solution diminishes the electrostatic bonds between the dye and the positively charged amino acids of the protein. In contrast to a mixture of water with organic solvent the effectivity of destaining is increased. An increase of temperature promotes the destaining process. To a certain degree (< 10%) the destaining procedure is accompanied with a loss of protein. Furthermore, the removal of CBB does not affect the yield of peptides in the mass spectrometric measurement. In the case of silver stained protein bands the destaining is accomplished by oxidation of the metallic silver attached to the protein by potassium ferricyanide or hydrogen peroxide (H2O2). The released silver ions are complexed subsequently by sodium thiosulfate.
Sources: en.wikipedia.org
It separates components in a liquid sample and measures their amounts using a detector. Results can indicate concentration, purity, or identity based on retention time and detector response. The technique works for mixtures that can be dissolved and filtered.
It offers high resolution, reproducibility, and compatibility with many sample types. A single run can separate and quantify multiple analytes. It is common in pharmaceutical, food, environmental, and industrial laboratories.
Samples must be soluble in a suitable mobile phase and free of particles that can block the column. Detector response depends on analyte structure, so some compounds need derivatization or alternative detection. Complex matrices may require extensive sample preparation.
System suitability is typically performed before each batch or according to the validated method and laboratory procedure. Some long runs include periodic checks during analysis. The required frequency depends on regulatory expectations and method performance.