Homogeneity, verification

The variation in the number content of colony-forming particles between samples in one reconstituted capsule (Tj) and between samples of different capsules of one batch (T2) were tested separately. Although the T,-value exceeded the critical values twice, the batch was still considered as being of good quality because the deviations of the critical value were small and considered to be of random nature. An additional homogeneity verification was performed using two alternative methods as described in the certification report [38]. 

After the verification of homogeneity and stability, the characterization of material can take place. Frequently, this step is named certification rather than characterization, which is wrong in view of the discussion about homogeneity and stability and their impact on the reference material. The certification of our reference material is more than the characterization of the material. Flowever, for most people working on the development of measurement methods, the characterization is the most interesting part of the project. This probably explains the huge amount of literature available. 

The GLP requirements for mixtures with carrier (40 CFR 160.113) were originally intended to address problems associated with the incorporation of test and control substances into feed, water, and other media for toxicology studies however, now these same requirements pertain to all other GLP-required studies, including those pertaining to re-entry and worker safety. The requirement involves (1) substantiation of test, control, and reference substance concentration through periodic analyses (2) verification of homogeneity and (3) determination of stability and, if applicable, also solubility. All of these requirements usually require chemical analysis, although bioassay may be necessary for microbial pesticides. 

The seminal report of an asymmetric homogeneous metal-catalyzed reaction described the copper-catalyzed group-transfer reaction from a diazoester to an alkene, Eq. 3 (2). This article provided experimental verification of the intervention of copper carbenoid olefin complexes in the catalytic decomposition of diazo com-... 

We emphasize that any utilization of Eq. (5) already rest upon a number of (often reasonable) assumptions. Equation (5) represents an ordinary deterministic differential equation, based on assumption of homogeneity, free diffusion, and random collision, and neglecting spatial [102] or stochastic effects [103]. While such assumptions are often vindicated for microorganisms, the application of Eq. (5) to other cell types, such as human or plant cells, sometimes mandates careful verification. 

Chan HK, Carr GP. Evaluation of a photodiode array detector for the verification of peak homogeneity in high-performance liquid-chromatography. Journal of Pharmaceutical and Biomedical Analysis 8, 271-277, 1990. 

An analytical solution was derived and used to calculate subsurface air pressure (equation 6) for a sinusoidal pressure fluctuation at the soil surface (equation 7), with the unsaturated zone consisting of homogenous soil. The initial condition was the mean air pressure throughout the unsaturated zone. Verification results are presented in the following section and the full derivation is presented in Appendix A. 

Mass spectrometry also allows rapid verification of the fidelity and homogeneity of proteins produced by genetic engineering [112-114], In most cases, verifying the sequence is not sufficient. It is necessary to check whether all the wanted covalent modifications are present. 

If homolytic scission of polymer main-chain is induced by mechanical fracture, primary mecbano-radical must be formed in a pair. However, for homogeneous polymers, like PE, PTFE and PB, it is hard to demonstrate the pair formation of mechano-radical. Simplest heterogeneous polymer, polypropylene, is probably the best sample for the purpose of experimental verification of pair formation of the mechano-radical. 

Normally, CRMs are used for the verification of accuracy, precision, and reliability of the results of analysis carried out in a laboratory (i.e., for checking the quality of its routine work). The CRM is analyzed at specific intervals and the results obtained are used to draw control charts (e.g., Shewhart chart) [63]. This allows visual assessment of the measurement system, the emergence of systematic errors, etc. Application of CRMs for the constmction of control charts is advantagous because of the homogeneity and stability of CRMs, and the ability to assess the accuracy of the results obtained in the laboratory by comparison with the certified value. 

Alternatively, the results from the gradient runs for each sample can be inputted into Drylab, ACD, or Chromsword for further optimization (see Sections 8.5.6.11). For the predicted experimental conditions (i.e., gradient slope, temperature, flow rate), if desired selectivity and resolution can be obtained, an experiment can be run for verification. The peak purity for the main analyte (MS and DAD detection) should be checked in the verification run. If the desired selectivity and/or the target analyte are not spectrally homogeneous, go to Step 6, Figure 8-37. 

Electrophoresis is a separation technique based on the movement of charged molecules in an electric field. Dissimilar molecules move at different rates and the components of a mixture will be separated when an electric field is applied. It is a widely used technique, particularly for the analysis of eomplex mixtures or for the verification of purity (homogeneity) of isolated molecules. 

The mixing process is validated by the verification of the homogeneity of mixed powders, for instance, by taking three samples at three different levels of the mixer (top, middle, and bottom) and determining the amount of different active substances in these samples. Each sample must be of the same size as in the kind of dosage form to be used. A mixing index can also be used. 

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