Analytical procedures specific activity

The specification serves to guide buyers it serves for comparison of batches to recommend analytical procedures for active ingredient or impurities to provide methods and criteria for identity of the active ingredient and to provide chemical and physical parameters as additional tests for judging the suitability of formulations. It ensures that the product is satisfactory for the use for which it was intended by requiring that the product possess defined chemical and physical characteristics that can be verified by test methods. 

A pharmacopoeial reference substance is intended for the determination of the main component of a substance or for the active ingredient of a pharmaceutical formulation which is usually present at a high proportion of the total. The reference substance is to be used as a primary standard in a specific method validated as prescribed in the ICH Guideline Validation of Analytical Procedure Methodology" (Technical Guide for the Elaboration of Monographs 1996 ICH Guideline 1997). the reproducibility of which is known. This is taken into account when the limits of acceptance (tolerance) for the substance or product are fixed (Daas and Miller 1997,1998). 

Reliable quality control in the field of pharmaceutical analysis is based on the use of valid analytical methods. For this reason, any analytical procedures proposed for a particular active pharmaceutical ingredient and its corresponding dosage forms shonld be validated to demonstrate that they are scientifically sonnd nnder the experimental conditions intended to be used. Since dissolntion data reflect drng prod-net stability and quality, the HPLC method used in snch tests shonld be validated in terms of accuracy, precision, sensitivity, specificity, rngged-ness, and robustness as per ICH guidelines. 

The potential for either antagonistic or potentiating effects for combinations of chemical compounds, in connection with their ultimate biological activity and the related health problems, emphasizes the importance of developing analytical procedures which can be used to quantitate levels of specific compounds in the presence of a wide variety of chemical substances, many of which may be present at very high concentrations. 

Bioassay A biological assay, or bioassay, is an analytical procedure capable of measuring the biologic activity of a substance based on a specific functional, biologic... 

In practice, the sensitivity of the analytical procedures determines the lower level of specific activity which can be used. Calculations based on the available values, and taking into account the radiation dose received by the system, show that the formation of tritiated radiolytic products in alkanes is no longer significant at specific activity levels below 0-5 Curies per mole. 

Analysis is an indispensable element of any biochemical investigation analytical methods will need to be used whether one needs such simple information as a protein concentration, or an enzyme activity, or the results of more complex studies like the sequence of a nucleic acid or the affinity of a protein for a specific ligand. From the diverse range of analytical techniques that can be exploited in biochemistry, we focus here on core methods for investigating the concentration, structure and stability of proteins and nudeic adds, and the essentials of enzymatic analytical procedures. 

Radiochemical methods of analysis are considerably more sensitive than other chemical methods. Most spectral methods can quantitate at the parts-per-mil-lion (ppm) level, whereas atomic absorption and some HPLC methods with UV, fluorescence, and electrochemical methods can quantitate at the parts-per-billion (ppb) levels. By controlling the specific activity levels, it is possible to attain quantitation levels lower than ppb levels of elements by radiochemical analyses. Radiochemical analysis, inmost cases, can be done without separation of the analyte. Radionuclides are identified based on the characteristic decay and the energy of the particles as described in detection procedures presented above. Radiochemical methods of analysis include tracer methods, activation analysis, and radioimmunoassay techniques. 

Fairly wide use has been made of preparative gel electrophoresis in protein chemistry, and in principle there is no reason why the same procedures should not be adopted for use with nucleic acids which have the advantage that much may be accomplished with very small quantities of purified material. Thus, it is relatively easy in many situations to introduce radioactive label at very high levels and specific activity, and the use of for this purpose offers a degree of sensitivity that cannot be matched in work on proteins. The extinction coefficients of nucleic acids are also very high in the ultraviolet, so that with say 20 pg in 1 ml or less it is possible to measure optical properties, thermal melting profiles, sedimentation coefficients, and even molecular weights by sedimentation equilibrium in an instrument equipped with scanner optics. Consequently, the sacrifice of resolution that, by a malign law of nature, always accompanies any attempt to scale up an analytical fractionation method is often at least partly avoided. 

The analyst usually has some information regarding the nature of the ion to be analyzed (inorganic or organic), its surface activity, its valency, and its acidity or basicity, respectively. With this information and on the basis of the selection criteria outlined schematically in Table 1-1, it should not be difficult for the analytical chemist to select a suitable stationary phase and detection mode. In many cases, several procedures are feasible for solving a specific separation problem. In these cases, the choice of the analytical procedure is determined by the type of matrix, the simplicity of the procedure, and, increasingly, by financial aspects. Two examples illustrate this ... 

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