The short version of calibration curve fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2026-02-10 and is reviewed periodically as new material appears.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Retention time RSD | ≤1% for five replicate injections | Typical criterion; method-specific limits apply. |
| Resolution | ≥1.5 between critical pair | Baseline separation is generally desired. |
| Tailing factor | ≤2.0 | Measures peak symmetry. |
| Theoretical plates | ≥2000 per column | Method-dependent; higher values indicate greater efficiency. |
| Peak area RSD | ≤2% for replicate injections | Reflects autosampler and detector precision. |
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.
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.
Validation demonstrates that a method is suitable for its intended use. Typical performance characteristics include accuracy, precision, specificity, linearity, range, limit of detection, limit of quantitation, and robustness. Regulators and standards organizations provide frameworks, but specific requirements depend on the application and jurisdiction. System suitability tests are run before sample analysis to confirm resolution, peak symmetry, retention time repeatability, and sensitivity. A validated method is not permanently fixed; changes may require partial or full revalidation.
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.
11 November An investigation by the Independent Police Conduct Authority concludes that several senior New Zealand Police executives including former Police Commissioner Andrew Coster had covered up allegations of serious offending lodged by a police employee against former Deputy Police Commissioner Jevon McSkimming. The government proposes the transfer of gun licensing responsibilities from the police to an independent Firearms Safety Authority. The Otago Regional Council extends OceanaGold's mining consent for its Macraes gold mine for another five years. 13 November – ACT leader and Deputy Prime Minister David Seymour's controversial Regulatory Standards Bill passes its third reading in Parliament, becoming law. 14 November: The New Zealand Government allocates NZ$2 million to the Dunedin Tunnels Trail cyclewear connecting Dunedin and Mosgiel. Several schools and early childhood centres close after the Ministry of Business, Innovation and Employment (MBIE) issues a recall notice for two coloured sands products over concerns about asbestos contamination. 17 November – The Supreme Court of New Zealand upholds a 2024 Court of Appeal decision that Uber drivers were employees rather than contractors. 18 November: Taumata Arowai, the national water regulator, takes control of the Northland town of Kāeo's drinking water supply from private contractor, Wai Care Environmental Consultants. The town had been under a boil water notice for ten years and lacked running water.
==== IEC/RPLC ==== IEC/RP MMC combines the advantages of RPLC and IEC. For example, WAX/RP has increased separation power and degree of freedom in adjusting the separation selectivity when compared with single WAX or RPLC.
Following Rollins' discovery in 1920 that lead aprons protected against X-rays, lead aprons with a lead thickness of 0.5 mm were introduced. Due to their weight, lead-free and lead-reduced aprons were subsequently developed. In 2005, it was recognized that in some cases the protection was significantly less than wearing lead aprons. The lead-free aprons contain tin, antimony and barium, which have the property of producing intense radiation (X-ray fluorescence radiation) when irradiated. In Germany, the Radiology Standards Committee has taken up the issue and introduced a German standard (DIN 6857-1) in 2009. The international standard IEC 61331-3:2014 was finally published in 2014. Protective aprons that do not comply with DIN 6857-1 of 2009 or the new IEC 61331-1 of 2014 may result in higher exposures. There are two classes of lead equivalency classes: 0.25 mm and 0.35 mm. The manufacturer must specify the area weight in kg/m2 at which the protective effect of a pure lead apron of 0.25 or 0.35 mm Pb is achieved. The protective effect of an apron shall be appropriate to the energy range used, up to 110 kV for low energy aprons and up to 150 kV for high energy aprons. If necessary, lead glass panels must also be used, with the front panels having a lead equivalent of 0.5-1.0 mm, depending on the application, and the side shields having a lead equivalent of 0.5-0.75 mm. Outside the useful beam, radiation exposure is primarily caused by scattered radiation from the tissue being scanned.
== History and Development == Tagging technology and instrument development occurred at the University of Toronto and DVS Sciences, Inc. CyTOF (cytometry by time of flight) was initially commercialized by DVS Sciences in 2009. In 2014, Fluidigm acquired DVS Sciences to become a reference company in single cell technology. The technology evolved through models like CyTOF, CyTOF2, Helios (CyTOF3) and CyTOF XT, with the latter announced in 2021. In 2022 Fluidigm received a capitol infusion and changed its name to Standard BioTools. In 2023, Standard BioTools introduced the Hyperion XTi Imaging System, advancing Imaging Mass Cytometry (IMC) with capabilities such as whole slide imaging, automated sample processing, and dual imaging/flow cytometry modes. In 2024, the company expanded its high-throughput imaging options with two additional rapid modes and an automated slide loader that can be installed directly on the Hyperion XTi for automatic loading and acquisition of up to 40 slides. Additionally, a 2024 collaboration with Navignostics was announced to develop clinical research applications using the Hyperion XTi system . In 2025, Standard BioTools announced the CyTOF XT Pro System, streamlining workflow with up to 4x faster throughput and software with 21 CFR Part 11 compliance enabling features.
Sources: en.wikipedia.org
The primary role of yeast is to convert the sugars present (namely glucose) in the grape must into alcohol. The yeast accomplishes this by utilizing glucose through a series of metabolic pathways that, in the presence of oxygen, produces not only large amounts of energy for the cell but also many different intermediates that the cell needs to function. In the absence of oxygen (and sometimes even in the presence of oxygen), the cell will continue some metabolic functions (such as glycolysis) but will rely on other pathways such as reduction of acetaldehyde into ethanol (fermentation) to "recharge" the co-enzymes needed to keep metabolism going. It is through this process of fermentation that ethanol is released by the yeast cells as a waste product. Eventually, if the yeast cells are healthy and fermentation is allowed to run to the completion, all fermentable sugars will be used up by the yeast with only the unfermentable pentose leaving behind a negligible amount of residual sugar.
== Ban == The BBB was banned, and restrictions were placed on the political activities of Schabort in November 1988, in reaction to the massacre of black South Africans in Pretoria by Barend Strydom. This was the first time such restrictions had been placed on a right wing organisation. In banning the group, Adriaan Vlok, the Law and Order Minister, said that the group were "right-wing, fanatical extremists who favour violence to carry racism to its extreme". In December 1988, Schabort re-launched the BBB as the Blanke Nasionale Beweging (White National Movement) under the nominal leadership of Wynand de Beer; however, as its activities were clearly the same as the BBB, it was banned at the beginning of 1989. The government lifted the ban on the BBB in February 1990. Schabort officially disbanded the BBB and the Blanke Party in 1990, and joined the Conservative Party. Some members of the BBB, like Keith Conroy, would go on to support the Afrikaner Volksfront.
These findings are based on decades of data, and control for cohort groups; the data avoids the risk that the drops in happiness during midlife are due to populations' unique midlife experiences, like a war. The studies have also controlled for income, job status and parenting (as opposed to childlessness) to try to isolate the effects of age. Researchers found support for the notion of age changes inside the individual that affect happiness. This could be for any number of reasons. Psychological factors could include greater awareness of one's self and preferences; an ability to control desires and have more realistic expectations – unrealistic expectations tend to foster unhappiness; moving closer to death may motivate people to pursue personal goals; improved social skills, like forgiveness, may take years to develop – the practice of forgiveness seems linked to higher levels of happiness; or happier people may live longer and are slightly overrepresented in the elderly population. Age-related chemical changes might also play a role. Other studies have found older individuals reported more health problems, but fewer problems overall. Young adults reported more anger, anxiety, depression, financial problems, troubled relationships and career stress. Researchers also suggest depression in the elderly is often due largely to passivity and inaction – they recommend people continue to undertake activities that bring happiness, even in old age.
Sources: en.wikipedia.org
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.
Retention time drift can result from changes in mobile phase composition, column temperature, pump flow, or column age. A gradual shift often points to column degradation. A sudden shift may indicate a leak, mixing error, or incorrect mobile phase.
Retention time alone cannot confirm identity because different compounds may elute at similar times. Coupling HPLC with mass spectrometry or comparing against authenticated standards increases confidence. Confirmation usually requires orthogonal data.
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.