The short version of accuracy fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2025-10-08 and is reviewed periodically as new material appears.
Validation establishes that a method is suitable for its intended purpose. Typical parameters include accuracy, precision, specificity, linearity, range, limit of detection, limit of quantification, robustness, and stability of standards and samples. Acceptance criteria are defined in advance, and results are documented in a validation report. Regulatory guidance for pharmaceuticals, foods, and environmental testing differs, so the applicable framework must be identified. Ongoing verification uses control samples and trend charts after validation. Method transfer to another laboratory may require partial revalidation.
Routine quality control includes blanks, duplicates, spiked samples, and certified reference materials. Calibration curves are prepared with standards at several concentrations, and the detector response is checked for linearity. Carryover, column aging, mobile phase evaporation, and temperature drift can shift retention times or peak areas. Maintenance such as replacing seals, filters, and columns helps prevent failures. Records of injections, integration, and deviations support traceability. Audits may request raw data and instrument logs for each batch.
Method validation establishes that an HPLC procedure is suitable for its intended use. Key parameters include accuracy, precision, specificity, linearity, range, limit of detection, limit of quantitation, and robustness. Accuracy measures agreement with a true or accepted value, while precision describes repeatability and intermediate precision. Specificity confirms that the method measures the analyte without interference from impurities, degradants, or excipients. Validation is documented in a protocol and report, and acceptance criteria are set before experiments begin. Regulatory guidance varies by region, but the general principles are widely harmonized.
System suitability testing is performed before and during analytical runs to confirm that the instrument and method are working as expected. Common checks include retention time, peak area, resolution between critical pairs, tailing factor, and theoretical plate count. Results are compared with predefined limits, and a failed check requires investigation before sample results are reported. Quality control samples at low, middle, and high concentrations are injected at intervals to monitor accuracy and precision. Blank injections detect carryover and contamination, while control charts track performance over time.
| Property | Value | Notes |
|---|---|---|
| Accuracy | Closeness to true value | Often assessed by recovery of spiked samples |
| Precision | Agreement among repeated measurements | Often reported as relative standard deviation |
| Specificity | Ability to measure analyte without interference | Must separate analyte from impurities and matrix |
| Linearity | Proportional detector response | Evaluated across a defined concentration range |
| Robustness | Resistance to small method changes | Tests flow rate, pH, temperature, and mobile phase composition |
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.
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.
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.
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.
Routine quality control uses system suitability, blank injections, check standards, and control samples to detect drift or contamination. System suitability criteria may specify minimum resolution, maximum tailing factor, and a permitted range for repeated injections. Blank injections reveal carryover or solvent contamination, while check standards confirm calibration accuracy over a batch. Control samples with known analyte levels can show whether results remain within statistical limits. When a control result falls outside limits, the analyst investigates the cause and may invalidate affected results before repeating the batch.
Documentation and traceability are central to regulated HPLC testing. Records typically include instrument logs, column history, mobile-phase preparation, sample preparation, injection sequences, raw chromatograms, and audit trails. Electronic systems may require user access controls, time-stamped changes, and backup procedures. Training records show that analysts are qualified for assigned methods. Audits and inspections check whether written procedures match actual practice and whether deviations are documented. These controls support reproducibility and allow results to be reconstructed if questions arise later.
Method validation establishes that an HPLC procedure is suitable for its intended purpose. Typical parameters include accuracy, precision, specificity, linearity, range, limit of detection, limit of quantitation, robustness, and solution stability. Accuracy reflects closeness to a reference value, while precision reflects agreement among repeated measurements. Specificity shows whether the method can measure the analyte without interference from matrix components. Validation is documented through protocols and reports, and the required extent depends on the method's use and regulatory context.
This must be especially the case for LCRs found in highly expressed proteins, since they should also have a great impact on the energy burden of protein translation. Thus, any prokaryotic LCRs that constitute evolutionary accidents with no functional significance should not be fixed by genetic drift and consequently should not demonstrate any levels of conservation among moderately distant evolutionary relatives. On the contrary, any LCR found among homologs of several moderately distant prokaryotic species should very probably reserve a functional role.
Inductively coupled plasma mass spectrometry (ICP-MS) is a type of mass spectrometry that uses an inductively coupled plasma to ionize the sample. It atomizes the sample and creates atomic and small polyatomic ions, which are then detected. It is known and used for its ability to detect metals and several non-metals in liquid samples at very low concentrations. It can detect different isotopes of the same element, which makes it a versatile tool in isotopic labeling. Compared to atomic absorption spectroscopy, ICP-MS has greater speed, precision, and sensitivity. However, compared with other types of mass spectrometry, such as thermal ionization mass spectrometry (TIMS) and glow discharge mass spectrometry (GD-MS), ICP-MS introduces many interfering species: argon from the plasma, component gases of air that leak through the cone orifices, and contamination from glassware and the cones.
A hormone is any of a class of signaling molecules produced by cells in glands in multicellular organisms that are transported by the circulatory system to target distant organs to regulate physiology and behaviour. Hormones have diverse chemical structures, mainly of 3 classes: eicosanoids, steroids, and amino acid/protein derivatives (amines, peptides, and proteins). The glands that secrete hormones comprise the endocrine system. The term hormone is sometimes extended to include chemicals produced by cells that affect the same cell (autocrine or intracrine signalling) or nearby cells (paracrine signalling). Hormones are used to communicate between organs and tissues for physiological regulation and behavioral activities, such as digestion, metabolism, respiration, tissue function, sensory perception, sleep, excretion, lactation, stress, growth and development, movement, reproduction, and mood. Hormones affect distant cells by binding to specific receptor proteins in the target cell resulting in a change in cell function. This may lead to cell type-specific responses that include rapid changes to the activity of existing proteins, or slower changes in the expression of target genes. Amino acid–based hormones (amines and peptide or protein hormones) are water-soluble and act on the surface of target cells via signal transduction pathways; steroid hormones, being lipid-soluble, move through the plasma membranes of target cells to act within their nuclei.
Sources: en.wikipedia.org
=== Pharmaceuticals === The expiration date of pharmaceuticals specifies the date the manufacturer guarantees the full potency and safety of a drug. Most medications continue to be effective and safe for a time after the expiration date. A rare exception is a case of renal tubular acidosis purportedly caused by expired tetracycline. A study conducted by the U.S. Food and Drug Administration covered over 100 drugs, prescription and over-the-counter. The study showed that about 90% of them were safe and effective as long as 15 years past their expiration dates. Joel Davis, a former FDA expiration-date compliance chief, said that with a handful of exceptions - notably nitroglycerin, insulin and some liquid antibiotics - most expired drugs are probably effective. Shelf life is not significantly studied during drug development, and drug manufacturers have economic and liability incentives to specify shorter shelf lives so that consumers are encouraged to discard and repurchase products. One major exception is the Shelf Life Extension Program (SLEP) of the U.S. Department of Defense (DoD), which commissioned a major study of drug efficacy from the FDA starting in the mid-1980s. One criticism is that the U.S. Food and Drug Administration (FDA) refused to issue guidelines based on SLEP research for normal marketing of pharmaceuticals even though the FDA performed the study. The SLEP and FDA signed a memorandum that scientific data could not be shared with the public, public health departments, other government agencies, and drug manufacturers.
NASA spin-off technologies are commercial products and services which have been developed with the help of NASA, through research and development contracts, such as Small Business Innovation Research (SBIR) or STTR awards, licensing of NASA patents, use of NASA facilities, technical assistance from NASA personnel, or data from NASA research. Information on new NASA technology that may be useful to industry is available in periodical and website form in "NASA Tech Briefs", while successful examples of commercialization are reported annually in the NASA publication Spinoffs. The publication has documented more than 2,000 technologies over time. In 1979, notable science fiction author Robert A. Heinlein helped bring awareness to the spin-offs when he was asked to appear before Congress after recovering from one of the earliest known vascular bypass operations to correct a blocked artery. In his testimony, reprinted in his 1980 book Expanded Universe, Heinlein claimed that four NASA spin-off technologies made the surgery possible, and that they were only a few from a long list of NASA spin-off technologies from space development. Since 1976, the NASA Technology Transfer Program has connected NASA resources to private industry, referring to the commercial products as spin-offs. Well-known products that NASA claims as spin-offs include memory foam (originally named temper foam), freeze-dried food, firefighting equipment, emergency "space blankets", DustBusters, cochlear implants, LZR Racer swimsuits, and CMOS image sensors.
Hong Kong & Macau: The Automated Passenger Clearance System (Chinese: 自助出入境檢查閘機), colloquially known as the e-Channel) is an automated border control facility available at airports in Hong Kong and Macau, and at land borders between the mainland and the Special Administrative Regions. It is open to residents in the appropriate regions, and to selected foreign nationals. In Hong Kong, the eChannel is also available to non-residents on departure, without registration, and to registered non-residents who qualify as "frequent travellers", including Chinese citizens from the Mainland, for both arrival and departure. Finally, Hong Kong's and Macau's eChannel systems recognise each other's Permanent Resident ID card, after registration in an automated kiosk at the ferry terminal. Japan: Along with the introduction of J-BIS, an "Automated gate" (Japanese: 自動化ゲート) was set up at Terminal 1 and 2 at Narita Airport, Haneda Airport, Chubu Centrair Airport and Kansai Airport. With this system, when a person enters or leaves the country, rather than having to be processed by an examiner there, a person can use a machine at the gate, thereby making both entry and departure simpler and easier, as well as more convenient. Japanese people with valid passports, foreigners with both valid passports (this includes refugees with valid travel certificates and re-entry permits) and re-entry permits can use this system.
In an interview for Politico on 5 February, María Corina Machado indicated that elections could be held in Venezuela in 9 to 10 months, using manual voting. She said that she had not discussed about elections with Trump. National Assembly president and brother of Delcy, Jorge Rodríguez ruled out the possibility of elections in the near future in an interview for Newsmax. In an interview for NBC on 12 February, Delcy Rodríguez was asked if she will hold free and fair elections, she answered "absolutely" adding it will be decided as part of the "political dialogue." Also interviewed for the NBC, US Secretary of Energy Chris Wright, speaking from Caracas, said that elections could be held in the Venezuela before the end of second presidency of Donald Trump, and added about Machado that he "listened to her in a podcast a few days ago, she was asked that question: how fast can they hold elections in Venezuela? What do you think should happen, María? And she said to get it, probably the fastest it could be done it probably takes 9 to 10 months to get there. So I think she is realistic about what the changes that need to happen.
Sources: en.wikipedia.org
== Early life == Cam McCormick was born to father Corey and mother Debra McCormick in Mesa, Arizona on April 2, 1998. His parents met in Arizona, and Corey had been a college baseball player at Arizona State University. Two years after McCormick's birth, his parents were divorced. Debra suffered a bout of melanoma—diagnosed at one point as stage 4—when McCormick was five years old. McCormick and his mother remained in the Phoenix metropolitan area until shortly before McCormick began the second grade in 2006 when his mother moved with him to Pennsylvania. McCormick and his mother returned to the Western United States in 2012, settling down in Bend, Oregon.
On the same day, Taliban-run Afghan Ministry of Defense said that they launched drones attack targeting military sites in Kohat, claiming to have inflicted significant losses. Later on, the ministry said that it had used two drones to strike a military facility near Islamabad. Pakistani officials denied the Taliban officials' claims and said that rudimentary drones had been intercepted and shot down in Kohat and Islamabad, injuring two civilians. They attributed the attacks to the Pakistani Taliban. In Pakistan's provincial capital of Quetta, two civilians were injured as result of falling debris from an intercepted drone, while in Lakki Marwat, six Pakistani police personnel were killed in a roadside bomb blast. The attack in Lakki Marwat was the deadliest in Pakistan since the onset of hostilities, although no group claimed responsibility for it.
The kidney is a vital organ with a variety of responsibilities. It plays an important role in maintaining the water, electrolyte and acid-base balance. It excretes toxic metabolic degradation products such as urea. It also recovers valuable substances such as glucose, amino acids, peptides and minerals initially filtered out of the blood during ultrafiltration in the renal corpuscles. In addition, endogenous and exogenous substances are metabolized and broken down in the kidneys—the kidney is therefore a central metabolic organ alongside the liver. Finally, some hormone-active substances are secreted by the kidney, such as renin, erythropoietin and calcitriol (active form of vitamin D3). As a result, the organ plays an important role in the regulation of blood pressure, new blood formation and the balance of calcium and phosphorus, and is thus crucial to bone metabolism, as well. As carnivores, cats are particularly dependent on the intake of animal proteins because glucose formation from amino acids is their most important energy source. The enzymes of amino acid degradation are adapted to the high protein intake and their activity is largely independent of the protein supply in the diet, so that cats break down endogenous proteins (especially from the muscles) when there is a lack of protein intake (catabolic metabolic state). Meat and offal also contain vital nutrients for the cat, such as Vitamin A, Taurin or arachidonic acid. Compared to a normal human diet, cats consume around six times as much phosphate in their diet with standard cat food.
Sources: en.wikipedia.org
System suitability is a set of checks performed before and during a run to confirm that the instrument, column, and method work as expected. Common checks include resolution, tailing factor, theoretical plates, and relative standard deviation of replicate injections. Failure triggers troubleshooting or method adjustment.
Validation demonstrates that a method produces reliable results for a defined purpose. It documents performance limits and acceptance criteria. Regulated industries require validation before routine testing of products or samples.
Retention time shifts can arise from changes in mobile phase composition, pH, temperature, column age, or flow rate. Contamination or worn seals may also alter pressure and delivery. Systematic checks of these factors help identify the cause.
System suitability is a set of checks that confirm the instrument and method perform within limits before sample analysis. It typically includes resolution, tailing factor, retention time, and peak area reproducibility. If a check fails, the run is invalidated until the cause is resolved.