If you have been reading about reversed-phase and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Updated 2025-08-31. Numbers and descriptions here follow the published literature rather than marketing material.
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.
Regulatory and pharmacopeial texts shape how HPLC testing is performed and documented. The International Council for Harmonisation provides validation guidance, while pharmacopeias publish general chromatography chapters and monographs for specific materials. Accreditation standards such as ISO/IEC 17025 address laboratory competence and traceability. Inspectors may review instrument qualification, analyst training, reference material control, and electronic records. Open questions include how best to validate methods for new complex products and how to handle automated data processing. Laboratories generally resolve these issues through risk assessment, method lifecycle management, and documented scientific justification.
Practical HPLC testing depends on careful sample preparation and instrument maintenance. Samples may require filtration, dilution, pH adjustment, or extraction to avoid column damage and matrix interference. Mobile phases are degassed and filtered, and columns are equilibrated before injection. Common problems include peak tailing, baseline drift, ghost peaks, carryover, and co-elution of analytes. Documentation of instrument logs, calibration records, and electronic audit trails supports data integrity and traceability. Ongoing training and routine maintenance help reduce variability between analysts and laboratories.
Quality control laboratories use HPLC to check identity, purity, concentration, and stability of raw materials and finished products. A validated method specifies the column, mobile phase, flow rate, detection wavelength, injection volume, and run time. Samples are prepared and compared against reference standards of known concentration. The resulting chromatogram provides quantitative data, such as assay values and impurity levels. This approach is common in pharmaceutical, food, environmental, and industrial testing where consistent measurements are required.
Method validation demonstrates that an analytical procedure is suitable for its intended purpose. Typical validation characteristics include accuracy, precision, specificity, linearity, range, limit of detection, limit of quantitation, and robustness. Regulatory guidance from bodies such as the International Council for Harmonisation and the United States Pharmacopeia outlines expectations, though specific criteria depend on the product and method. System suitability tests are run before sample analysis to confirm resolution, peak symmetry, column efficiency, and injection repeatability. Failure of these checks can invalidate a batch of measurements.
| Property | Value | Notes |
|---|---|---|
| Primary guidance | ICH Q2(R2) | Analytical procedure validation |
| Compendial chapter | USP <621> | Chromatography general chapter |
| Validation parameter | Accuracy | Closeness to accepted true value |
| System suitability check | Peak resolution | Ensures separation between adjacent peaks |
| Data record | Audit trail | Supports data integrity and traceability |
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.
Laboratories apply HPLC testing across pharmaceutical, food, environmental, and industrial chemistry. The method can measure active ingredients, impurities, additives, preservatives, and degradation products. Sample preparation often includes dilution, filtration, and sometimes extraction or derivatization. The choice of column, mobile phase, pH, temperature, and detector depends on the analytes and matrix. Results are compared with reference standards to assign identity and concentration. Method suitability is judged by resolution, precision, and accuracy.
HPLC testing is not a single fixed procedure; it is a family of separation modes. Reversed-phase, normal-phase, ion-exchange, size-exclusion, and affinity chromatography each suit different analyte properties. Reversed-phase methods dominate because they handle many neutral and moderately polar compounds. Detection can be optical, electrochemical, or mass spectrometric, and the detector dictates what information is available. Coupling with mass spectrometry increases selectivity and enables identification when standards are unavailable. The technique cannot separate every mixture without adjustment.
HPLC testing is an analytical technique used to separate, identify, and quantify components in a liquid sample. It relies on a pressurized mobile phase that carries the sample through a column packed with stationary phase. Different compounds travel at different rates because of interactions with the stationary and mobile phases. The resulting signal versus time is a chromatogram. Peak position indicates identity under specified conditions, while peak area or height relates to amount.
== Zusammensetzung des Urins == Urin ist ein Ausscheidungsprodukt des Körpers, das die von der Niere ausgeschiedenen Stoffe enthält: vor allem Wasser, Mineralstoffe, Endprodukte des Eiweißstoffwechsels, Säuren und weitere Stoffe, darunter Harnstoff. Harnstoff wird in der Evidenzbasierten Medizin zur Behandlung mancher Hautkrankheiten eingesetzt. Entgegen der weit verbreiteten Ansicht, dass Urin beim gesunden Menschen in der Blase keimfrei sei, enthält er schon dort eine Vielzahl verschiedener Bakterien. Da die untere Harnröhre nicht keimfrei ist, enthält Urin beim Austritt bis zu 10.000 Keime pro Milliliter. Gegen eine Anwendung des Eigenurins spricht zudem die Gefahr, dass dieser bei Harnwegsinfektionen mit weiteren Bakterien verunreinigt sein kann, welche in den erkrankten Hautpartien zusätzlich Entzündungen hervorrufen können (beispielsweise Escherichia coli, Chlamydien oder Gonokokken).
== Geschichte == Im Spätmittelalter ist die Therapie mit Eigenharn, etwa in Kombination mit Baldrian und Bibernellen-Wurzel, zur innerlichen Behandlung der „Pest“ in einem in der Berner Burgerbibliothek aufbewahrten, von dem elsässischen „Laienarzt“ Anton Trutmann um 1495 verfassten Arzneibuch belegt, das Conrad Brunner 1903 „ans medizinische Licht des Tages gebracht“ hat. In der ersten Hälfte des 20. Jahrhunderts wurde die Eigenharntherapie durch den britischen Autor John W. Armstrong bekannt. Armstrong kurierte sich seinen eigenen Angaben zufolge durch ein 45-tägiges Fasten, während dessen er ausschließlich Wasser und seinen eigenen Urin zu sich genommen habe, von einer als „unheilbar“ diagnostizierten Tuberkulose. Auslöser für seinen Versuch war eine Bibelstelle des Alten Testaments: Im Buch der Sprichwörter heißt es in Kapitel 5, Vers 15: „Trinke Wasser aus deiner Zisterne und was quillt aus deinem Brunnen“. Allerdings befasst sich dieses Kapitel mit einer Warnung an die Männer vor dem Ehebruch, und verwendet in diesem Zusammenhang die Begriffe „deine Zisterne“ und „dein Brunnen“ als Metapher für die eigene Gattin. In den folgenden Jahrzehnten nahm Armstrong die Supervision von mehreren tausend Fällen von Urin-Fastenkuren vor. Seine Beobachtungen veröffentlichte er in dem 1944 erschienenen Buch „The Water of Life“. Armstrong schrieb, und andere Urintherapeuten stimmen ihm hierbei zu, dass die Diagnose bei der Eigenurintherapie so gut wie keine Rolle spiele, da nahezu alle Krankheiten angeblich auf diese spezielle Therapie ansprechen würden.
In Deutschland wurde die Eigenurintherapie Anfang der 90er Jahre einer breiten Öffentlichkeit durch die Journalistin Carmen Thomas bekannt, die in ihren Sendungen das Thema aufgriff und 1993 das Buch Urin – ein ganz besonderer Saft publizierte.
Trinken Trinkkuren Harnfasten äußerlich (Einreibungen, Wickel, Packungen, Fußbäder, Gurgeln) bei Hautkrankheiten: Akne, Neurodermitis, Schuppenflechte zur Hautpflege Zellulitis Wundheilung Warzen Eigenharn-Injektionen Hierbei wird der Harn vor der Injektion untersucht, keimfrei gemacht und dann subkutan injiziert. Es gibt auch Methoden, bei denen nur die (nach Meinung der Vertreter dieser Therapieform) wirksamen Bestandteile extrahiert und dann ähnlich der Homöopathie aufbereitet werden.
Sources: de.wikipedia.org
System suitability is a set of checks performed before and during an HPLC run to confirm that the instrument and method are working as expected. It may include retention time repeatability, resolution between peaks, peak symmetry, and signal intensity. Failing suitability criteria usually invalidates the run.
An HPLC method is typically validated before its routine use and revalidated in part when significant changes affect the method. Regulators do not set a universal calendar interval. The need for revalidation depends on the change, its risk, and the applicable guidance.
Validation establishes that a method is suitable for its intended purpose, often through a planned study. Verification confirms that a laboratory can reproduce a previously validated or compendial method under its own conditions. Verification is usually narrower than full validation.
Method validation is the documented process of confirming that an HPLC procedure is suitable for its intended use. It evaluates accuracy, precision, specificity, linearity, range, detection limits, and robustness. Validation criteria depend on the regulatory context and the sample type.