A practical reference on precision: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2025-11-09. Anything still debated is marked as such rather than presented as settled.
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.
Routine HPLC testing depends on controlled reagents, calibrated instruments, and documented procedures. Columns degrade over time, so retention times and peak shapes are monitored for drift. Mobile phases are filtered and degassed to prevent pump damage and detector noise. Reference standards must be traceable and stored under suitable conditions. Data handling systems record injections, calculations, and audit trails. Quality control samples interspersed with unknowns help detect errors during a run.
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.
| 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 |
Detection commonly uses ultraviolet-visible absorbance, fluorescence, refractive index, or mass spectrometry. Ultraviolet detection depends on molecular chromophores that absorb light at specific wavelengths. Mass spectrometry provides mass information and sensitive quantification, often after electrospray ionization. Before sample batches, performance checks examine resolution, elution time repeatability, peak symmetry, and plate count. Matrix effects and co-elution remain recognized uncertainties; formal validation studies and orthogonal detection help address them. Detector choice depends on analyte properties and required sensitivity.
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.
GLP-1 is effective at reducing blood glucose levels. GLP-1 analogs have a significant therapeutic effect and high efficacy on diabetes treatments and hypoglycemia prevention. Proliferation effect and trophic effect on the small intestine, GLP-2 is used as a therapy to support patients with short-bowel syndrome and other underlying intestinal conditions. Proglucagon Overview at colostate.edu Nosek, Thomas M. "Section 6/6ch2/s6ch2_27". Essentials of Human Physiology. Archived from the original on 2016-03-24. Enteroglucagon at the U.S. National Library of Medicine Medical Subject Headings (MeSH)
Chromosome walking can be used for the purpose of cloning a gene. It does this by using the known gene’s markers that are closest and can therefore be used in techniques like isolating DNA sequences and aiding in the sequencing and cloning of the DNA of organisms. Chromosome walking is also useful when it comes to filling in the gaps that may be present in genomes by locating clones that overlap with a library clone end. This means that for chromosome walking to be carried out, it requires a clone library of a genomic format. This is why Vectorette PCR is one of the methods that can be used to create this library for chromosome walking to occur. Vectorette PCR comes in handy when it is necessary to obtain the regions that are both upstream and downstream and flank a sequence that is already known. By obtaining these regions, it provides the library of a genomic format that chromosome walking requires.
The YES/YAS assay is performed in 96-well microtiter plates. Total assay time is usually 2–3 days, but faster protocols (18 hrs. exposure time) using induced cell lysis have been developed. Several yeast cell lines have been developed for the YES and YAS assay, both proprietary and publicly available. Commercial kits with all necessary ingredients and detailed instructions are also available. Substances with an activating or inhibitory effect on the estrogen and/or androgen receptor of organisms may interfere with reproduction, affect the metabolism and immune system and induce the formation of tumors. This assay is suitable for detecting numerous natural and synthetic hormonally active substances such as environmental toxins from everyday products, e.g. birth control pill ingredients (17α-ethinylestradiol), synthetic materials (bisphenol A, phthalates), pesticides (methoxychlorine) and non-ionic surfactants (alkylphenols). The test has a good reproducibility and concordance with literature data of in vivo or in vitro data.
The Green Chemistry Institute (GCI) supports the "implementation of green chemistry and engineering throughout the global chemistry enterprise." The GCI organizes an annual conference, the Green Chemistry and Engineering Conference, provides research grants, administers awards, and provides information and support for green chemistry practices to educators, researchers, and industry. The GCI was founded in 1997 as an independent non-profit organization, by chemists Joe Breen and Dennis Hjeresen in cooperation with the Environmental Protection Agency. In 2001, the GCI became a part of the American Chemical Society.[1]
Introduced in 2007, ChIP sequencing (ChIP-seq) is a technology that uses chromatin immunoprecipitation to crosslink the proteins of interest to the DNA but then instead of using a micro-array, it uses the more accurate, higher throughput method of sequencing to localize interaction points. DamID is an alternative method that does not require antibodies. ChIP-exo uses exonuclease treatment to achieve up to single base pair resolution. CUT&RUN sequencing uses antibody recognition with targeted enzymatic cleavage to address some technical limitations of ChIP.
Sources: en.wikipedia.org
Abelacimab (MAA868), is a fully human monoclonal antibody for the treatment of thrombosis, under development by Anthos Therapeutics. It is anti-factor XI antibody. The hope behind its development is that factor XI plays a bigger role in thrombosis (via the intrinsic/contact activation pathway) than hemostasis, so targeting it might reduce clotting risks without a corresponding increase in bleeding. It has, indeed, shown overwhelming reduction in bleeding as compared to a direct oral anticoagulant (rivaroxaban) in patients with atrial fibrillation and a moderate-to-high risk of stroke. Data is insufficient for drawing a conclusion on whether it increases or decreases stroke events as compared to rivaroxaban. Antibody Monoclonal antibody Immunology
Protein Data Bank (PDB) is a database of three dimensional structures of biological macromolecules, such as proteins and nucleic acids. The data are typically obtained by X-ray crystallography or nuclear magnetic resonance spectroscopy (NMR spectroscopy), and submitted manually by structural biologists worldwide through PDB member organizations – PDBe, RCSB, PDBj and BMRB. The database can be accessed through the webpages of its members, including PDBe (housed at the EMBL-EBI). As a member of the Worldwide Protein Data Bank (wwPDB) consortium, PDBe aids in the joint mission of archiving and maintenance of macromolecular structure data.
Mycosporine–like amino acids are rather small molecules (<400 Da). The structures of over 30 MAAs have been resolved and all contain a central cyclohexenone or cyclohexenimine ring and a wide variety of substitutions. The ring structure is thought to absorb UV light and accommodate free radicals. All MAAs absorb ultraviolet wavelengths, typically between 310 and 362 nm. They are considered to be amongst the strongest natural absorbers of UV radiation. It is this light absorbing property that allows MAAs to protect cells from the harmful UV-B and UV-A components of sunlight. Biosynthetic pathways of MAAs depend on the specific MAA molecule and the organism that is producing it. These biosynthetic pathways often share common enzymes and metabolic intermediates with pathways of the primary metabolism. An example is the shikimate pathway that is classically used to produce the aromatic amino acids (phenylalanine, tyrosine and tryptophan); with many intermediates and enzymes from this pathway utilized in MAA biosynthesis.
In vitro testing suggests that unidentified wolfberry phytochemicals in goji tea may inhibit metabolism of medications, such as those processed by the cytochrome P450 liver enzymes, including such drugs as warfarin. Organochlorine pesticides are conventionally used in commercial wolfberry cultivation to mitigate infestation by insects. China's Green Food Standard, administered by the Chinese Ministry of Agriculture's China Green Food Development Center, permits some pesticide and herbicide use. Agriculture in the Tibetan Plateau (where many "Himalayan" or "Tibetan"-branded berries supposedly originate) conventionally uses fertilizers and pesticides, making organic claims for berries originating there dubious. Since the early 21st century, high levels of insecticide residues (including fenvalerate, cypermethrin, and acetamiprid) and fungicide residues (such as triadimenol and isoprothiolane), have been detected by the United States Food and Drug Administration in some imported wolfberries and wolfberry products of Chinese origin, leading to the seizure of these products.
Mouse MA-10 cells respond to 5-oxo-ETE but lack OXER1. It has been suggested that these cells' responses to 5-oxo-ETE are mediated by an ortholog to OXER1, mouse niacin receptor 1, Niacr1, which is a G protein-coupled receptor for niacin, or, alternatively, by one or more of the mouse hydroxycarboxylic acid (HCA) family of the G protein-coupled receptors, HCA1 (GPR81), HCA2 (GPR109A), and HCA3 (GPR109B), which are G protein-coupled receptors for fatty acids.
Sources: en.wikipedia.org
In 2017, PTC acquired Emflaza (deflazacort) from Marathon Pharmaceuticals. PTC also owns Translarna, (Ataluren) marketed for nonsense mutation Duchenne muscular dystrophy. Together, the two products generated revenues of 174 million dollars and 260 million dollars in 2017 and 2018 respectively. PTC has the commercialization rights for WAYLIVRA (volanesorsen) in Latin America. In 2018, PTC acquired Agilis Biotherapeutics and a gene therapy candidate, GT-AADC, with its compelling clinical data in treating aromatic L-amino acid decarboxylase (AADC) deficiency. AADC deficiency is a rare CNS disorder arising from reductions in the enzyme AADC that result from mutations in the dopa decarboxylase (DDC) gene. As of 2024, the AAV based treatment for AADC deficiency has been approved by the FDA and commercialized in the United States as Kebilidi. It is the first FDA-approved gene therapy treatment for AADC deficiency. This same product was granted EMA approval for use in the European Union under the name Upstaza.
Increased health awareness: Regular testing can help individuals identify health trends and potential issues early, enabling proactive health management. Convenience and accessibility: At-home collection and direct ordering eliminate barriers such as scheduling appointments, obtaining referrals, and taking time off work. Cost transparency: Upfront pricing allows consumers to make informed decisions about testing costs. Patient empowerment: Direct access to health data supports informed decision-making and engagement in personal health management. In 2014 the federal government issued a regulation directing clinical laboratories to provide individuals with access to their test data upon request.
Cannabis Analytical Science Program (CASP) is a forum where the science of hemp and cannabis analysis can be discussed and cannabis standards and methods developed. Analytical Solutions Forum (ASF) brings global stakeholders together to identify emerging needs and technologies in scientific analysis of food and related products. === Botanical Ingredients and Dietary Supplement Integrity Program === AOAC’s Botanical Ingredient and Dietary Supplement Integrity (BIDSI) Program focuses on coordinating all future consensus-driven need for development, validation, and implementation of methods for the analysis of a wide range of botanical ingredients and dietary supplements. === Stakeholder Program on Infant Formula and Adult Nutritionals === Stakeholder Program on Infant Formula and Adult Nutritionals program (SPIFAN) develops consensus-based standards and methods to make infant formula and adult nutritionals safer for babies and adults to consume.
Industrial breeding of plants has unintentionally altered how agricultural cultivars associate with their microbiome. In maize, for example, breeding has altered the nitrogen cycling taxa required to the rhizosphere, with more modern lines recruiting less nitrogen fixing taxa and more nitrifiers and denitrifiers. Microbiomes of breeding lines showed that hybrid plants share much of their bacterial community with their parents, such as Cucurbita seeds and apple shoot endophytes. In addition, the proportional contribution of the microbiome from parents to offspring corresponds to the amount of genetic material contributed by each parent during breeding and domestication.
The ACAM2000 vaccine is produced from the vaccinia virus, which is sufficiently closely related to smallpox to provide immunity, but the ACAM2000 vaccine cannot cause smallpox because it does not contain the smallpox virus. Other vaccines containing live viruses include measles, mumps, rubella, polio and chickenpox. The vaccine is administered using a bifurcated stainless steel needle. The needle is dipped into the vaccine solution and used to prick the skin several times in the upper arm. The vaccinia virus will begin to grow at the injection site. It will cause a localized infection, with a red itchy sore produced at the vaccination site within three to four days. If the infection occurs, that is an indication that the vaccine was successful. Ultimately, the sore turns into a blister and then dries up. A scab forms and then falls off in the third week, leaving a small scar behind.
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.
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.