CHARACTERIZATION OF ANALYTICAL PATTERNS
ABOUT THE CHARACTERIZATION
The unambiguous identification of a substance can be considered as utopian, the more correct it would be identification in greater probability or as close to existing standards as either reference standards or analytical data in reliable bibliographic research.
Assigning identification to a major compound or even impurity of a product requires accountability and reliable analytical testimony
In the pharmaceutical industry, reliable reference standards produced by accredited entities and evaluated by international and / or national bodies are used. For a standard to be considered Reference to at least 5 reliable laboratories, they should analyze the product and issue the results for evaluation by a provider. There are several legislations which define reference substances.
· Primary Pattern;
· Secondary Pattern;
· Comparison Pattern;
Each pattern has its specific use and evaluated its use in function of the criticality of the product against the impacts to the human being, fauna and flora.
Resolution RDC No. 166 of July 24, 2017 describes nomenclature for standards as follows:
· SQR- (chemical reference substance): means a substance or mixture of high purity chemical or biological substances, which has been carefully characterized to ensure its identity, quality, content and potency including a reference chemical and a pharmacopoeial reference chemical;
· SQC- (chemical reference substance characterized): substance or mixture of chemical or biological substances in which the identity, quality, purity, content and potency have been ensured by a characterization process;
· SQF- (chemical reference substance pharmacopoeia): substance or mixture of chemical or biological substances established and distributed by official compendia recognized by Anvisa;
· SQT- (chemical substance of work): means a substance or a mixture of chemical or biological substances used in laboratory routine, standardized from a pharmacopoeial reference chemical or, in the absence thereof, from a characterized chemical reference substance, being traceable SQR used for its standardization.
Reference standards, also called primary standards, in Brazil are produced by the Brazilian Pharmacopoeia (mandatory use) or by institutions such as USP, BP (British Pharmacopoeia), FE (European Pharmacopoeia) and suppliers of standards that adopts the ISO-IEC-34 standard.
Reference or Primary standards have high prices in relation to the quantity of the presentation (milligrams), considering that most are imported and resold in Brazil, the ratio can be from 1mg to 200 units of national currency.
The pharmaceutical industry, in its internal quality control for release of raw material and finished product, usually uses the secondary standard. Today it is allowed to work with the characterized standard.
Characterized Standard: The T&E Center offers the characterization:
I. Challenging with a primary standard,
II. Assays by means of monograph for identification with tests in specific analytical techniques, reporting the characterization and quantification (power).
III. For microbiological techniques, the standard challenge is usually Reference (primary)
The analytical techniques depend on the characteristics of each molecule. In this way the analytical techniques are directed, after theoretical evaluation of each molecule.
The analytical technique with method indicative of stability shall be compendial, or validated by the client or by the T & E Center. In the case of no defined method, the development process is necessary, which involves: bibliographical research, search for solubility of the active and impurities, coeluition check, physical properties, search for stationary phase and mobile phase if it is HPLC or CFG, exploratory test, among others.
In the case of purity of a Reference Chemical, Quantification Limits are interesting to define the presence of impurities to be discounted in the calculation of the power, as long as they are highly impacting or necessary the determination for registration purposes. Monographs for content determination generally involve: Volatile substances; Semi-volatile substances; Non-volatile substances; Inorganic Substances, water, among other possible impacts on quantification.
For the characterization, the analytical techniques will be in function of the molecule and the analytical resources employed, among the techniques most used are:
· Liquid phase chromatography (UPLC or HPLC-UV / Vis; Fluorescence; ELSD);
· LC-MS / MS: Mass Spectrometry coupled to HPLC or UPLC;
· ICP-OES (Induced-Simultaneous and Sequential Plasma); AA - (Atomic Absorption) and FC (photometry of flame);
· DSC; TG / DTG; IVFT; UV / Vis; High resolution microscopy, wet testing; among others.
· NMR H and C; Diffraction X (techniques to be outsourced);
It can be observed that in paragraph 4 of Resolution RDC No. 166 of July 24, 2017, Chapter IV of the parameters of Analytical Validation, if necessary, guides the combination of two or more analytical methods of identification, that is, there is a need to do all the identification techniques..
Section I The Selectivity
Article 19 The selectivity of the analytical method shall be demonstrated by its ability to identify or quantify the analyte of interest unequivocally in the presence of components that may be present in the sample as impurities, diluents and matrix components.
Single paragraph. In the case of chromatographic methods, the chromatographic purity of the analyte signal must be demonstrated, except for biological products.
Art. 20 In methods of identification, its ability to obtain a positive result for the sample containing the analyte and a negative result for other substances present in the sample must be demonstrated.
§1º Paragraph 1 SQR should be used in comparison with the response obtained for the analyte under Chapter III.
§2º In order to demonstrate the selectivity of the identification methods, the tests shall be applied to substances structurally similar to the analyte, with the acceptance criteria being negative results.
§3º For active pharmaceutical inputs of plant origin and medicinal products containing them, the ability of the method to distinguish the material of interest from other similar plant species, especially those that may be present as adulterants or substituents, must be demonstrated.
§4º To achieve the required level of selectivity, it may be necessary to combine two or more analytical methods of identification.