WHO Expert Committee on Specifications for Pharmaceutical Preparations - WHO Technical Report Series, No. 885 - Thirty-fifth Report
(1999; 168 pages) [Spanish] View the PDF document
Table of Contents
View the documentWHO Expert Committee on Specifications for Pharmaceutical Preparations
View the document1. Introduction
Open this folder and view contents2. The international pharmacopoeia and related issues
Open this folder and view contents3. International Chemical Reference Substances and Infrared Reference Spectra
Open this folder and view contents4. Quality control - national laboratories
Open this folder and view contents5. Good manufacturing practices
Open this folder and view contents6. Quality systems and inspection
Open this folder and view contents7. Other quality assurance topics
Open this folder and view contents8. Nomenclature and terminology
Open this folder and view contents9. Legal aspects of pharmaceuticals
Open this folder and view contents10. Regulatory issues
Open this folder and view contents11. Training activities
View the document12. Pharmaceuticals contaminated with diethylene glycol
View the documentAcknowledgements
View the documentReferences
View the documentAnnex 1. List of available International Chemical Reference Substances1
View the documentAnnex 2. List of available International Infrared Reference Spectra1
Close this folderAnnex 3. General guidelines for the establishment, maintenance and distribution of chemical reference substances
View the documentIntroduction
Close this folderPart A. Primary chemical reference substances
View the document1. Assessment of need for the establishment of chemical reference substances
View the document2. Obtaining source material
Open this folder and view contents3. Evaluation of chemical reference substances
Close this folder4. Chemical and physical methods used in evaluating chemical reference substances
View the document4.1 Methods used to verify the identity of chemical reference substances
View the document4.2 Methods used to determine the purity of chemical reference substances
View the document5. Assignment of content
Open this folder and view contents6. Handling and distribution of chemical reference substances
View the documentPart B. Secondary chemical reference substances
View the documentReferences
Open this folder and view contentsAnnex 4. Good manufacturing practices: authorized person - role, functions and training
Open this folder and view contentsAnnex 5. Good manufacturing practices: supplementary guidelines for the manufacture of pharmaceutical excipients
Open this folder and view contentsAnnex 6. Guidelines for inspection of drug distribution channels
View the documentAnnex 7. Good pharmacy practice in community and hospital pharmacy settings
Open this folder and view contentsAnnex 8. National drug regulatory legislation: guiding principles for small drug regulatory authorities
Open this folder and view contentsAnnex 9. Provisional guidelines for developing training programmes: inspection and examination of counterfeit pharmaceuticals
View the documentWorld Health Organization Technical Report Series
View the documentSelected WHO Publications of Related Interest
View the documentBack Cover
 
4.1 Methods used to verify the identity of chemical reference substances

Where a proposed substance consists of a compound whose structure has been satisfactorily defined, its identity may be confirmed by matching the IR spectra of the substance to that of an authentic compound. Particular care should be taken when polymorphism exists (7). Other highly specific techniques, such as NMR spectroscopy, MS, or X-ray diffraction crystallography, may also be used for such comparisons. The identity of a substance that is intended to replace an established chemical reference substance of the same molecular constitution must be verified, to determine that the characteristic properties of the two specimens are identical. For this purpose it is often sufficient to compare their IR absorption spectra.

However, where no authentic specimen of the proposed substance is available for comparison, and definitive data about its properties are lacking, it may be necessary to verify its identity by applying several analytical techniques currently used to characterize new compounds. Such analytical methods may include elemental analyses, crystallographic studies, MS, NMR spectroscopy, functional group analyses, and IR or UV spectrophotometry, as well as other supplementary tests as required to establish that the proposed substance is fully characterized.

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