The short version of stationary phase fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2026-03-30. Anything still debated is marked as such rather than presented as settled.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Separation mode | Reversed-phase | Nonpolar stationary phase with polar mobile phase |
| Typical column particle size | 3–5 µm | Smaller particles improve resolution but raise pressure |
| Typical flow rate | 0.5–2.0 mL/min | Depends on column dimensions and pressure limits |
| Common detection | UV-Vis absorbance | Requires analytes with chromophores |
| Typical run time | 5–30 min | Varies with method, gradient, and sample complexity |
In quality control laboratories, HPLC testing supports batch release, raw material checks, stability studies, and impurity profiling. A validated method defines sample preparation, instrument settings, calibration, and acceptance criteria. Analysts compare results with specifications and investigate out-of-specification outcomes before a batch is approved. Documentation includes chromatograms, integration records, audit trails, and reagent details. Because results influence product decisions, laboratories follow formal quality systems and data integrity rules. The exact tests and limits depend on the material, its intended use, and the applicable regulatory framework.
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.
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 is an analytical technique that separates components in a liquid sample. A pump moves a liquid mobile phase through a column packed with a solid stationary phase. Compounds interact differently with both phases and travel at different rates, leaving the column at distinct retention times. A detector records these arrivals as peaks on a chromatogram. The resulting pattern supports identification and quantification of substances in mixtures. Modern instruments use high pressure to force solvent through small particles, which improves speed and resolution compared with older low-pressure liquid chromatography methods.
Separation in HPLC depends on the chemistry of the stationary phase, the composition of the mobile phase, and the physical properties of the column. Reverse-phase separations use a nonpolar stationary phase and a polar mobile phase, and they are common for many organic compounds. Ion-exchange, size-exclusion, and normal-phase modes serve other classes of analytes. Gradient elution changes solvent strength over time, while isocratic elution holds it constant. Flow rate, temperature, particle size, and column length all influence peak shape and resolution. Detection may use ultraviolet absorbance, fluorescence, refractive index, or mass spectrometry, depending on the analyte and the required sensitivity.
Routine HPLC testing compares a sample result with a calibration curve prepared from known reference standards. Peak area or peak height is plotted against concentration, and the curve is used to estimate unknown amounts. Retention time supports tentative identification when compared with a standard, though mass spectrometry or another confirmatory method may be needed for definitive identification. Pre-run checks verify repeatability, resolution, and peak symmetry before sample analysis. Limits of detection and quantification describe the smallest amounts that can be reliably observed or measured. Sample preparation, filtration, and degassing help prevent column damage and inconsistent results.
== Pharmacokinetics == The volume of distribution of Mobocertinib at steady state is 3,509 L. The mean oral bioavailability of Mobocertinib is 37%. The median Tmax is 4 hours. The average half-life of Mobocertinib and its metabolites is 18 hours. Mobocertinib is metabolized by CYP3A enzymes.
=== Antiasthmatic medicines and medicines for chronic obstructive pulmonary disease === Budesonide Budesonide/formoterol (budesonide + formoterol) Epinephrine (adrenaline) Ipratropium bromide Salbutamol Tiotropium
== Spectroscopy and magnetism == In contrast to most organic compounds, many inorganic compounds are magnetic and/or colored. These properties provide information on the bonding and structure. The magnetism of inorganic compounds can be complex. For example, most copper(II) compounds are paramagnetic but CuII2(OAc)4(H2O)2 is almost diamagnetic below room temperature. The explanation is due to magnetic coupling between pairs of Cu(II) sites in the acetate.
Sources: en.wikipedia.org
== See also == 25-NB Arylcyclohexylamine List of benzimidazole opioids List of orphine opioids List of phenyltropanes Opioid Structural scheduling of synthetic cannabinoids Substituted cathinone Utopioid
=== Effect on metabolism === Horses with PSSM have elevated levels of muscle glycogen at rest. During exercise, glycogen levels are depleted faster than is seen in unaffected horses, and are reduced down to levels considered normal for a resting non-PSSM horse. This demonstrates that glycogen metabolism is actually normal in these animals. However, PSSM horses synthesize muscle glycogen at double the rate of a normal horse once exercise has ceased, which leads to elevated muscle glycogen. The exact mechanism of abnormal glucose metabolism has not yet been established, but it may have similarities to phosphofructokinase deficiency in humans. Quarter Horse-related breeds with PSSM show insulin sensitivity, which improves glucose uptake by cells, and these horses clear the blood of glucose more quickly after eating than unaffected horses. This provides easy access to glucose by the muscles, which can then use the substrate to produce glycogen. The GSY1 defect, which up-regulates the glycogen synthase enzyme, allows the muscles to use this glucose to rapidly produce glycogen for storage in the muscle. Surprisingly, increased insulin sensitivity is not seen in draft horse breeds. Dietary and exercise manipulation may be used to counteract these metabolic changes. Approximately 50% of horses that adhere to the dietary recommendations, and 90% of horses that adhere to both dietary and exercise recommendations, have few to no episodes of exertional rhabdomyolysis.
1993/1626) Castle Vale Housing Action Trust (Area and Constitution) Order 1993 (S.I. 1993/1634) Gipsy Encampments (Borough of Surrey Heath) Order 1993 (S.I. 1993/1635) Tower Hamlets Housing Action Trust (Area and Constitution) Order 1993 (S.I. 1993/1636) Value Added Tax (General) (Amendment) (No. 5) Regulations 1993 (S.I. 1993/1639) Reconstitution of the Witham First District Internal Drainage Board Order 1993 (S.I. 1993/1640) Import (Plant Health Fees) (England and Wales) Order 1993 (S.I. 1993/1641) Plant Passport (Plant Health Fees) (England and Wales) Regulations 1993 (S.I. 1993/1642) Environmental Protection (Controls on Injurious Substances) (No. 2) Regulations 1993 (S.I. 1993/1643) Alcan Aluminium UK Ltd. (Rateable Values) (Scotland) Order 1993 (S.I. 1993/1644) Forth Ports plc (Rateable Values) (Scotland) Order 1993 (S.I. 1993/1645) Caledonian MacBrayne Limited (Rateable Values) (Scotland) Order 1993 (S.I. 1993/1646) Tunbridge Wells and Eridge Light Railway Order 1993 (S.I. 1993/1651) Asylum and Immigration Appeals Act 1993 (Commencement and Transitional Provisions) Order 1993 (S.I. 1993/1655) Immigration (Restricted Right of Appeal against Deportation) (Exemption) Order 1993 (S.I. 1993/1656) Immigration (Variation of Leave) (Amendment) Order 1993 (S.I. 1993/1657) Extraction Solvents in Food Regulations 1993 (S.I. 1993/1658) Education (Assisted Places) (Scotland) Amendment Regulations 1993 (S.I. 1993/1659) St Mary's Music School (Aided Places) Amendment Regulations 1993 (S.I. 1993/1660) Asylum Appeals (Procedure) Rules 1993 (S.I.
Sources: en.wikipedia.org
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.
It offers high resolution, reproducibility, and compatibility with many sample types. A single run can separate and quantify multiple analytes. It is common in pharmaceutical, food, environmental, and industrial laboratories.
Samples must be soluble in a suitable mobile phase and free of particles that can block the column. Detector response depends on analyte structure, so some compounds need derivatization or alternative detection. Complex matrices may require extensive sample preparation.
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.