Validation with Commercial Standards

For smaller laboratories, the work involved in validation is often difficult, but there are two alternatives. Users can choose a system with an existing standardized and validated protocol and validated interpretation system. Commercially available kits generally provide these, and when utilized exactly as described in the kit insert, are guaranteed to provide diagnostically useful results. A second option would be to use one of the more common standard systems of fixatives with known antibodies, in which publication data has provided some evidence of functionality. As an example, a laboratory could use a 10% neutral buffered formalin fixation with a standard protocol, followed by a biotin-streptavidin HRP system, using a monoclonal antibody combination called AE1/AE3. This has been proven to be a reliable measure of cytokeratin in tissue sections. 

Considerable advances in methods for the detection, identification and quantification of anthocyanins have been made recently, particularly with the advent of UPLC and improved mass spectroscopy methods. Additional work is needed, particularly with quantitation using MS. However, the biggest limitation in the quantitation of anthocyanins is the commercial availability of anthocyanin standards, which are nonexistent for most anthocyanins, and those that are available are fairly expensive. Some laboratories have been able to isolate and purify the particular anthocyanins of interest (Ling et ah, 2009 Nakamura et al., 2010), but most laboratories do not have the equipment, time, and/or expertise to fully validate the anthocyanin standards. 

At a minimum, documentation of the characterization and stability of a standard, such as a certificate of analysis (Co A) and/or a certificate of stability (CoS), is typically available from the suppliers. The certificate should be obtained and recorded. The quantity of reference standard is typically limited in commercial kits designed for research use, and it is not uncommon that the reference material values may differ substantially between lots and manufacturers [16]. Novel biomarkers rarely have established gold standards against which their potency and abundance can be calibrated. A comparison of available sources can be useful, and when validating an assay for advanced applications it is desirable to plan ahead to obtain and reserve a sufficient supply of the same reference material. The example in Fig. 6.5 compares three reference standard curves, each prepared from a concentrated stock solution from a commercial supplier, an in-house reference standard, and a commercial kit, respectively. The instrument responses (optical density, OD) were highest with the standard from the commercial stock, the lowest with the kit, while the in-house reference standard response was intermediate. In this case, either the same commercial stock or the in-house reference standard can be used throughout the clinical study. 

Commercial learner s permit (CLP) A permit issued to an individual by a state or other jurisdiction of domicile, in accordance with the standards in 49 CFR 383, which, when carried with a valid driver s license issued by the same state or jurisdiction, authorizes the individual to operate a class of a commercial motor vehicle when accompanied by a holder of a valid commercial driver s license (CDL) for purposes of behind-the-wheel training. When... 

To check the accuracy of the quantification method, a double validation has been performed using caffeine as an external standard. In a first test, a set of 12 commercially available compotmds was investigated. These compounds contain nitrogen in different oxidation states in various fimctional groups. For a cross-validation with a larger set of compotmds, the ma j or difficulty was finding another generic quantification method. In our laboratory, a quantification method based... 

In order to do this, experimental determinations of the intrinsic viscosities of both the standards and the fractions from the unknown polymer are required. It is possible to obtain commercial gel permeation chromatographs that will do this routinely, and hence to exploit the concept of universal cali-hration. Care must he taken, though, to ensure that the separation of the polymer molecules occurs purely as a result of size exclusion. If there are any other specific interactions, e.g. hydrogen bonding, between the polymer and the column packing, such as may occur with water-soluhle polymers, Benoit s approach does not work and the universal cafihrafion plot is not valid. 

In order to make the problem solvable, a linearized process model has been derived. This enables the use of standard Mixed Integer Linear Programming (MILP) techniques, for which robust solvers are commercially available. In order to ensure the validity of the linearization approach, the process model was verified with a significant amount of real data, collected from production databases and production (shift) reports. 

This test uses the entire HPTC system with a specific chromatographic method and validated Cl8 column that should be <10 cm and commercially available. Validated means that the individual column was performance tested before being shipped and that a certified test chromatogram is included with each column. Injection precision testing is typically performed by replicate injections of a test standard (at least six replicates are suggested). One then calculates the peak area %RSD of a stable component in the test standard. Most LC... 

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