This is a working overview of quality control, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-05-12. Anything still debated is marked as such rather than presented as settled.
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.
Developing an HPLC test begins with defining the analytes, matrix, and required reporting limits. Chemists select a separation mode, column chemistry, mobile phase composition, flow rate, and detection wavelength or mass transition. Experiments then adjust these variables to achieve adequate retention, resolution, and peak shape. System suitability tests confirm that the instrument and method perform consistently before sample analysis. Without suitable resolution, quantitative results may be unreliable. Preliminary runs often use scouting gradients to locate retention windows.
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.
| Property | Value | Notes |
|---|---|---|
| Accuracy | Recovery near 100% | Depends on acceptance criteria and matrix |
| Precision | Relative standard deviation | Often at or below 2% for replicate injections |
| Limit of detection | Signal-to-noise ratio 3:1 | Approximate and method-specific |
| Limit of quantitation | Signal-to-noise ratio 10:1 | Confirmed by precision and accuracy |
| Resolution | 1.5 or greater | Typical system suitability target |
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.
Data handling and documentation are central to HPLC quality control. Electronic systems should have audit trails that record changes to methods, sequences, and results. Integration parameters, such as peak baseline and threshold, can affect reported areas and must be defined in advance. Out-of-specification results trigger a structured investigation that may include reanalysis, instrument checks, and review of sample preparation. Regulatory inspections often examine raw data, audit trails, and training records to verify that reported results are traceable and reliable.
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.
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.
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.
The Political Reform Act bill began to be discussed in the Francoist Cortes on November 14, two days after a general strike called by the democratic opposition which had an appreciable following. Put to vote on November 18 the Suarez government obtained a resounding success when it was approved by 435 procuradores, while only 59 were opposed, 13 abstained and 24 did not vote. This was achieved with the invaluable collaboration of the president of the Cortes, Fernández Miranda: the Act was processed by the urgency procedure, which limited the debates and the final vote was not secret; the procurators who held high positions in the administration were warned that they ran the risk of losing them if they did not support the it; others were promised that they could renew their positions in the new Cortes that were to be elected by forming part of candidacies that the government was willing to support. This would explain why the Francoist Cortes had decided to "commit suicide" ─ to harakiri by their own decision, as some newspapers headlined the day after the vote.
== Miscellaneous == It has been suggested that MAF can be formed by probiotic bacteria in a yoghurt medium. This probiotic mixture has been found to be helpful in various immune disturbances including ME/CFS.
== Awards and honours == 1995: Max-Bergmann-Medal of the MBK Society 2004: Josef Rudinger Award of the European Peptide Society 2011: Doctor honoris causa, University of Cergy-Pontoise, Paris 2018: Akabori Memorial Lecture Award of the Japanese Peptide Society 2020: Ernesto Scoffone Award of the Italian Peptide Society
Sources: en.wikipedia.org
After the U.S. atomic bombs were dropped on Hiroshima and Nagasaki on August 6 and 9, 1945, an additional 130,000 people - in addition to the 100,000 immediate victims - died from the effects of radiation by the end of 1945. Some experienced the so-called walking ghost phase, an acute radiation sickness caused by a high equivalent dose of 6 to 20 Sievert after a lethal whole-body dose. The phase describes the period of apparent recovery of a patient between the onset of the first massive symptoms and the inevitable death. In the years that followed, a number of deaths from radiation-induced diseases were added. In Japan, the radiation-damaged survivors are called hibakusha (Japanese: 被爆者, lit. ''Explosion victim'') and are conservatively estimated to number about 100,000.
== Taxonomy == Although unnamed Ambrosiella-like fungi had previously been documented from the galleries and mycangia of native X. crassiusculus populations in central Japan, A. roeperi was first described as a novel species of ambrosia fungus by Harrington and McNew in 2014 based on isolations from beetles collected and trapped in the eastern United States, where it is invasive. It has not been assigned a common name at the time of this writing. All Ambrosiella are ambrosia beetle symbionts and belong to the family Ceratocystidaceae, which, where sexual stages are recognized, produce round, ostiolate (with a pore) fruiting bodies for their ascospores with a fine peridium (outer layer) and aseptate (lacking crosswalls) paraphyses (sterile tissue found among – and arising from the same surface as – spore-bearing cells). This family also includes Ceratocystis, representing several plant pathogens and sap-staining fungi, often transported by insects (including scolytine beetles); Chalaropsis, encompassing a few economically insignificant root diseases; Huntiella, primarily made up of saprobes associated with lesions on trees, transported by sap beetles and in one case an Ips bark beetle; Thielaviopsis, containing various agents of disease affecting monocots; Davidsoniella, comprising several species of tree pathogens, and Endoconidiophora, growing on conifers, producing disease and/or sap stain, and also often acting as a bark beetle associate.
==== India ==== Codeine preparations require a prescription in India. A preparation of paracetamol and codeine is available in India. Codeine is also present in various cough syrups as codeine phosphate including chlorpheniramine maleate. Pure codeine is also available as codeine sulphate tablets. Codeine containing cough medicine has been banned in India with effect from 14 March 2016. The Ministry of Health and Family Welfare has found no proof of its efficacy against cough control.
Tifluadom is a benzodiazepine derivative with an unusual activity profile. Unlike most benzodiazepines, tifluadom has no activity at the GABAA receptor, but instead is a selective agonist for the κ-opioid receptor. It has potent analgesic and diuretic effects in animals, and also has sedative effects and stimulates appetite. While tifluadom has several effects which might have potential uses in medicine, such as analgesia and appetite stimulation, κ-opioid agonists tend to produce undesirable effects in humans such as dysphoria and hallucinations, and so these drugs tend to only be used in scientific research. Dysphoric effects are similar to those seen when using other κ-opioid receptor agonists like pentazocine and salvinorin A, and can be considered the opposite of morphine-induced euphoria. As such, kappa agonists are believed to have very limited abuse potential.
Sources: en.wikipedia.org
Validation establishes suitability for a new method, while verification confirms that a method works in a specific laboratory. Verification is often used when a validated method is adopted with existing equipment and staff. Both rely on documented acceptance criteria.
Quantification usually compares detector response to a standard curve made from reference standards. The curve may be external, internal, or based on standard addition depending on matrix effects. Results are reported with units and, when required, uncertainty.
Carryover occurs when analyte from a previous injection remains in the system and appears in a later chromatogram. It can come from the injector, column, or tubing. Blank injections and needle washes help detect and reduce it.
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.