Aspects of Assays

Any method of blood sampling (finger prick, venepuncture, venous line) is satisfactory. Anticoagulated specimens (heparin, EDTA, acid citrate) are more convenient, since separation of red cells and plasma permits diagnostic assays of glycosylated hemoglobin and glycosylated albumin to be performed on one blood sample. 

Although many different procedures have been described for preparation prior to glycosylated hemoglobin assay, a standard method applicable to 

In those methods that do not distinguish the labile aldimine adduct from the stable ketoamine component, the former may be removed by incubating red cells in glucose-free isotonic saline or buffered media for 12 hours (D2). However, specific acid catalysis of the aldimine adduct is rapid (30 minutes) and complete at pH 5-6 and is achieved by incubating red cells or hemoly-sate with concentrated (0.2-0.6 M) buffers (e.g., borate, acetate) in the pH 

5 range. This was preferable and more effective than to discharge the aldimine complex by poisonous chemicals, namely, at pH 5 for 30 minutes with 30 mM semicarbazide and 12 inM aniline (N3) or sodium acetate-buffered saline (B15). Adaptations of these principles in commercial methods have been reported (N4). 

If preparatory prerequisites are followed, samples for glycosylated hemoglobin and plasma protein assays may be stored, depending on refrigeration temperatures, for months and years without loss of activity. 

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Many forms of patch tests exist. Duration of patch exposure has varied between 1 and 72 h. The singleapplication patch procedure outlined by the NAS (1977) incorporates important aspects of assays used by many investigators. The procedure is similar to FHSA tests in rabbits. 

Practical Aspects of Assays with Synthetic Peptide Substrates. 132... 

The International Conference on Harmonisation (ICH) has issued an extensive guidance covering all aspects of assay vali-... 

Implication of Different Types of Pharmacogenomics Studies on Aspects of Assay Design... 

Some general comments on, and practical aspects of, assay design... 

Process validation should be extended to those steps determined to be critical to the quality and purity of the enantiopure drug. Establishing impurity profiles is an important aspect of process validation. One should consider chemical purity, enantiomeric excess by quantitative assays for impurity profiles, physical characteristics such as particle size, polymorphic forms, moisture and solvent content, and homogeneity. In principle, the SMB process validation should provide conclusive evidence that the levels of contaminants (chemical impurities, enantioenrichment of unwanted enantiomer) is reduced as processing proceeds during the purification process. 

Blinks, J. R., et al. (1978). Practical aspects of the use of aequorin as a calcium indicator Assay, preparation, microinjection, and interpretation of signals. Method. Enzymol. 57 292-328. 

A number of high-throughput enantiomeric excess assays have been developed, yet none are completely general. This crucial aspect of directed evolution of... 

In this chapter, the main aspects of mass spectrometry that are necessary for the application of LC-MS have been described. In particular, the use of selected-ion monitoring (SIM) for the development of sensitive and specific assays, and the use of MS-MS for generating structural information from species generated by soft ionization techniques, have been highlighted. Some important aspects of both qualitative and quantitative data analysis have been described and the power of using mass profiles to enhance selectivity and sensitivity has been demonstrated. 

Primer design is one of the most important aspects of a robust PCR assay. In general, primers should be designed such that they are not able to form secondary structures such as stemloop or hairpin configurations. A primer must not be complementary at the 3 end, as this will cause primer dimers to form. All primers should have similar melting temperatures and should not contain stretches of individual nucleotides. There are software programs available to assist in primer design, but it is crucial that primers are tested in the assay, especially in a multiplex system. 

The conventional analytical process is comprised of sampling — sample preparation —> analysis —> calculation —> approval of results — report — decision.93 The introduction of productivity measurements to focus attention on continuous improvement and improving the reliability of assays to eliminate re-analysis can aid in re-engineering the process for greater efficiency.93 Automation is another important aspect of improving efficiency.94 The rate-limiting steps in many industrial laboratories, however, may precede or... 

The application of PSA measurements for clinical monitoring of prostatic carcinoma requires fine tuning of PSA assays. One important aspect of this tuning is to have well-defined standards (primary calibrators). Calibrators or primary reference materials consisting of PSA complexed with ACT have been prepared and are available to sponsors of commercial immunoassays. As a result of this, some sponsors have studied calibration stability and have shown that calibration did not change within 14 to 90 days. Primary references of 90 percent PSA-ACT and 10 percent f-PS A have been shown to minimize differences in PSA measurements between different assays [NCCLS Document—Primary Reference Preparations Used to Standardize Calibration of Immunochemical Assays for Serum Prostate... 

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