Everything below concerns Calibration curve. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2026-08-01. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Primary guidance | ICH Q2(R2) | Analytical procedure validation |
| Compendial chapter | USP <621> | Chromatography general chapter |
| Validation parameter | Accuracy | Closeness to accepted true value |
| System suitability check | Peak resolution | Ensures separation between adjacent peaks |
| Data record | Audit trail | Supports data integrity and traceability |
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.
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.
== Business == Keep-it Technologies has developed a time and temperature indicator (TTI) that shows the actual remaining shelf life of products, which is significantly better than the traditional static date stamp. It is based on temperature over time, and each indicator is tailored to the products shelf life profile. The technology behind the indicator has been developed and verified at the University, before a working prototype was finally developed. Keep-it Technologies has patented the indicator in a number of countries, including the USA. Keep-it Technologies’ shelf-life indicator comprises two small chambers with different ingredients that react and change colour depending on time and temperature. A blue bar moves gradually from left to right and eventually disappears. The blue bar moves slow at low temperatures and faster as the temperature increases. The indicator is attached as a self-adhesive label to the packaging by the food producer. It monitors the time and temperature the packages is exposed to from production, during transport, at the retailer, and in the consumer's own fridge. In this way the device gives more correct indication of remaining shelf life (days left) than traditional date-stamping, because it takes into account the actual temperature to which the individual food package has been exposed. Benefits by using the indicator: Reduce food waste for both retailer & consumer, increase food safety & quality, and gain control over the whole cold chain, and reduce customer complaints.
=== Plasma fractionation and Wiener directorship === In 1952, operation commenced plasma fractionation. Thereafter the range of antivenoms increased, including those against other snake species such as death adder (Acanthophis antarcticus) and the taipan (Oxyuranus scutellatus), plus spiders including the redback (Latrodectus hasselti) and – after much difficulty – the Sydney funnel-web (Atrax robustus). Much of this work, including the introduction in 1962 of a polyvalent antivenom against all of the major terrestrial Australian snakes, occurred under the direction of Saul Wiener, while from 1966 until the mid-1990s, venom research was coordinated by the eccentric but dedicated Struan Sutherland, who in 1979 released new guidelines for snakebite first aid, and a new test for snakebites that would identify which snake had envenomated the victim. Other major achievements of CSL include:
Due to the monoamine oxidase inhibitor (MAOI) activity of ayahuasca, it has a prominent risk of drug interactions with other monoaminergic agents. As an example, combination of ayahuasca with a selective serotonin reuptake inhibitor (SSRI) can result in potentially life-threatening serotonin syndrome.
Most of these studies optimized the oxytocin quantification in electrospray ionization (ESI) positive mode, using [M+H]+ as the parent ion at mass-to-charge ratio (m/z) 1007.4 and the fragment ions as diagnostic peaks at m/z 991.0, m/z 723.2 and m/z 504.2. These important ion selections paved the way for the development of current methods of oxytocin quantification using MS instrumentation. The structure of oxytocin is very similar to that of vasopressin. Both are nonapeptides with a single disulfide bridge, differing only by two substitutions in the amino acid sequence (differences from oxytocin bolded for clarity): Cys – Tyr – Phe – Gln – Asn – Cys – Pro – Arg – Gly – NH2. Oxytocin and vasopressin were isolated and their total synthesis reported in 1954, work for which Vincent du Vigneaud was awarded the 1955 Nobel Prize in Chemistry with the citation: "for his work on biochemically important sulphur compounds, especially for the first synthesis of a polypeptide hormone." Oxytocin and vasopressin are the only known hormones released by the human posterior pituitary gland to act at a distance. However, oxytocin neurons make other peptides, including corticotropin-releasing hormone and dynorphin, for example, that act locally. The magnocellular neurosecretory cells that make oxytocin are adjacent to magnocellular neurosecretory cells that make vasopressin. These are large neuroendocrine neurons which are excitable and can generate action potentials.
Magnetic nanoparticles for therapeutic applications are selected based on their properties determined by the nanoparticle composition which can be divided into three main groups - metal only, metal alloy, or metal oxide nanoparticles. Some key properties of magnetic nanoparticles include a large specific surface area, desirable biocompatibility, presence without causing disease or eliciting immune response, and superparamagnetism. Magnetic nanoparticles are influenced by an external magnetic field due to the magnetic moment found within the network unit. The external magnetic field is necessary for transport and activation of these nanoparticles. Therefore, when a drug is attached/encased in magnetic nanoparticles, these particles will be targeted using an external magnetic field to guide and concentrate the drug at desired disease locus. Design of magnetic nanoparticles for clinical application requires careful evaluation of the effects of surface modification, size, and shape on its magnetic properties. Ferromagnetic properties of nanoparticles have been used in magnetic drug delivery systems. This is important, as ferromagnetism is described as the coercivity of particles to form macro-materials on permanent magnets. The macro-materials include iron, cobalt, and nickel; these elements retain their magnetic properties when a magnet is removed, which is why they accumulate on the permanent magnets. Iron oxides, such as Fe2O4 and Fe3O4 in particular, play a key role in magnetic nanoparticle drug delivery. The particle sizes typically range from 3 nm to 30 nm.
Sources: en.wikipedia.org
When analyzed in the lower-dimensional PCA space, clustering of samples with similar metabolic fingerprints can be detected. PCA algorithms aim to replace all correlated variables with a much smaller number of uncorrelated variables (referred to as principal components (PCs)) and retain most of the information in the original dataset. This clustering can elucidate patterns and assist in the determination of disease biomarkers – metabolites that correlate most with class membership. Linear models are commonly used for metabolomics data, but are affected by multicollinearity. On the other hand, multivariate statistics are thriving methods for high-dimensional correlated metabolomics data, of which the most popular one is Projection to Latent Structures (PLS) regression and its classification version PLS-DA. Other data mining methods, such as random forest, support-vector machines, etc. are received increasing attention for untargeted metabolomics data analysis. In the case of univariate methods, variables are analyzed one by one using classical statistics tools (such as Student's t-test, ANOVA or mixed models) and only these with sufficient small p-values are considered relevant. However, correction strategies should be used to reduce false discoveries when multiple comparisons are conducted since there is no standard method for measuring the total amount of metabolites directly in untargeted metabolomics. For multivariate analysis, models should always be validated to ensure that the results can be generalized.
Food and Agriculture Organization (FAO) Codex Alimentarius (a commission of the United Nations) US Food and Drug Administration (FDA) European Union World Health Organization (WHO) There are seven basic principles:
=== Treatment === The opioid epidemic is often discussed in terms of prevention, but helping those who are already addicted is addressed less frequently. Opioid dependence can lead to a number of consequences like contraction of HIV and overdose. For addicted persons who wish to treat their addiction, there are two classes of treatment options available: medical and behavioral. Neither is guaranteed to successfully treat opioid addiction. Which treatment, or combination of treatments, is most effective varies from person to person. These treatments are doctor-prescribed and -regulated, but differ in their treatment mechanism. Popular treatments include kratom, naloxone, methadone, and buprenorphine, which are more effective when combined with a form of behavioral treatment. Accessing treatment, however, can be difficult. The strict regulation of opioid treatment programs dates back to the early 20th century. Before 1919, physicians prescribed milder forms of opiates to help wean patients off opium. In Webb v. United States, the Supreme Court ruled that doctors could no longer prescribe narcotics to aid in treating a narcotic use disorder. Thus, morphine dispensaries emerged in communities to fill the treatment gap and were the early precedents to modern methadone clinics. It is still difficult for providers to prescribe opioids for medication-assisted treatment despite the data that show individuals addicted to opioids have better outcomes with that than abstinence-based treatment programs.
=== Epstein-Barr virus === The Epstein-Barr virus (EBV) infects about 90 to 95% of adults and can cause infectious mononucleosis. A study of more than 10 million US military members compared 801 people who developed MS to 1,566 matched controls who did not. The study found a 32-fold increased risk of MS development following EBV infection. It did not find an increased risk after infection with other viruses, including the similar cytomegalovirus. These findings strongly suggest that EBV is necessary for MS onset, although EBV alone may be insufficient to cause it. The nuclear antigen of EBV, which is the most consistent marker of EBV infection across all strains, has been identified as a direct source of autoreactivity in the human body. These antigens appear more likely to promote autoimmunity in vitamin D deficient persons. The EBV protein EBNA1 shares similarities with three human proteins, including the brain protein GlialCAM. Because of molecular mimicry, the immune system in MS mistakenly may attack these proteins. Two are part of the nervous system, while the third is a "guardian molecule" which protects the body against autoimmunity.
=== mzPeak === Due to the increasing size of mass spectrometry raw-data files, the XML-backed mzML specification does not perform well enough with compressed data. The mzPeak format solves that by saving multiple files in an uncompressed zip file, with the raw data stored in parquet files for fast random access. The structure of the format is heavily inspired by mzML. Its specification is under development, as of September 2026, by HUPO-PSI and interested parties.
Sources: en.wikipedia.org
== Further reading == Gollner, Adam J. (2010). The Fruit Hunters: A Story of Nature, Adventure, Commerce, and Obsession. Scribner. ISBN 978-0-7432-9695-3. Watson, R. R., and Preedy, V.R. (2010, eds.). Bioactive Foods in Promoting Health: Fruits and Vegetables. Academic Press. ISBN 978-0-12-374628-3.
Following extended discussions with Richwood Pharmaceuticals regarding the resolution of a large number of issues related to the company's numerous violations of FDA regulations, the FDA formally approved the first Obetrol labeling/sNDA revisions in 1996, including a name change to Adderall and a restoration of its status as an approved drug product. In 1997 Richwood Pharmaceuticals was acquired by Shire Pharmaceuticals in a $186 million transaction. Richwood Pharmaceuticals, which later merged with Shire, introduced the Adderall brand in 1996 as an instant-release tablet. In 2006, Shire agreed to sell rights to the Adderall name for the instant-release form of the medication to Duramed Pharmaceuticals. DuraMed Pharmaceuticals was acquired by Teva Pharmaceuticals in 2008 during their acquisition of Barr Pharmaceuticals, including Barr's Duramed division. The first generic version of Adderall IR was introduced to the market in 2002. Later on, Barr and Shire reached a settlement agreement permitting Barr to offer a generic form of the extended-release drug beginning in April 2009.
In 1887, a laboratory for the study of bacteria, the Hygienic Laboratory, was established within the Marine Hospital Service, which at the time was expanding its functions beyond the system of Marine Hospitals into quarantine and research programs. It was initially located at the New York Marine Hospital on Staten Island. In 1891, it moved to the top floor of the Butler Building in Washington, D.C. In 1904, it moved again to a new campus at the Old Naval Observatory, which grew to include five major buildings. In 1901, the Division of Scientific Research was formed, which included the Hygienic Laboratory as well as other research offices of the Marine Hospital Service. In 1912, the Marine Hospital Service became the Public Health Service (PHS). In 1922, PHS established a Special Cancer Investigations laboratory at Harvard Medical School. This development marked the beginning of partnerships with universities. In 1930, the Hygienic Laboratory was re-designated as the National Institute of Health by the Ransdell Act, and was given $750,000 to construct two NIH buildings at the Old Naval Observatory campus. In 1937, the NIH absorbed the rest of the Division of Scientific Research, of which it was formerly part. In 1938, the NIH moved to its current campus in Bethesda, Maryland. Over the next few decades, Congress would markedly increase funding of the NIH. Various institutes and centers within the NIH were created for specific research programs. In 1944, the Public Health Service Act was approved and the National Cancer Institute became a division of the NIH.
The most abundant mass is the location of the most abundant peak of an isotopometric cluster, as observed by mass spectrometry. Because it is an observed value, it is affected by the resolution of the spectrometer being used. This value can be theoretically calculated by first obtaining a list of exact peaks using the natural abundances of the isotopes, then applying a blurring/smearing operation to simulate the resolution of the actual instrument. This is also called "isotope cluster prediction". Because isotopes differ in mass from each other by a nearly integer amount of Da, the peaks also tend to occur in spacings of 1 Da: this leads to the observed clustering. The most abundant mass tends to be different from the monoisotopic mass for larger molecules: the more atoms there are, the higher the chances that there is at least one atom that is not the most abundant isotope (see the negative binomial distribution). As a result it is important in the identification of larger molecules. There are pre-calculated tables (derived from a binomial distribution) that allow for efficient hand-calculation of the most abundant mass to an integer precision.
Sources: en.wikipedia.org
System suitability is a set of checks performed before and during an HPLC run to confirm that the instrument and method are working as expected. It may include retention time repeatability, resolution between peaks, peak symmetry, and signal intensity. Failing suitability criteria usually invalidates the run.
An HPLC method is typically validated before its routine use and revalidated in part when significant changes affect the method. Regulators do not set a universal calendar interval. The need for revalidation depends on the change, its risk, and the applicable guidance.
Validation establishes that a method is suitable for its intended purpose, often through a planned study. Verification confirms that a laboratory can reproduce a previously validated or compendial method under its own conditions. Verification is usually narrower than full validation.
It measures the presence and amount of one or more compounds in a liquid sample. Separation occurs in a column, and detection produces a signal proportional to concentration. Identification usually requires comparison with a known reference standard under the same conditions.