Bioanalytical applications method development

Online SPE LC/MS/MS is commonly used for bioanalytical applications in the pharmaceutical industry. Column switching systems and TFC systems are easy to build and control. Sophisticated commercial systems and SPE cartridges are readily available. Compared to offline sample preparation, the online approach can save time and labor. However, the development of online SPE bioanalytical assays remains analyte-dependent. Generic methods can be applied to many analytes. For extremely hydrophobic, hydrophilic, and ionic analytes at normal pH range and analytes with a variety of hydrophobicity and pKa values, analyte-specific methods must be developed. An understanding of the chemistry of the analytes and SPE is critical. 

Biotech macromolecule drugs are chemically and biologically different from the small-molecule drugs. Special considerations must be given for bioanalytical method development, validation and applications, including the purity of the re-... 

Tan A, Montminy V, Gagne S, Musuku A, Masse R (2009) Trouble-shooting of least-expected causes in bioanalytical method development and application. Presented at 2009 AAPS annual meeting and exposition, Los Angeles, California, USA, 8-12 Nov... 

The distinctions within the drug-discovery environment previously noted naturally favor the use of simpler and faster sample-preparation techniques. However, most all sample-preparation methods are potentially viable choices, as recent applications have demonstrated method-development techniques that are both rapid and selective. Also, there is value for the quick development of a bioanalytical method with selectivity for a series of similarly related structures, as that one method can often meet the needs for PK and toxicokinetic (TK) studies well into the discovery process, rather than just for one initial study. The variety of sample-preparation methodologies for bioanalysis are now detailed. 

Xu et al. [43] published a report on a process for rapid HPLC-MS/MS method development in a drug discovery setting. In this report, the authors provided a three-step process for rapid bioanalytical method development for HPLC-MS/MS methods suitable for drug discovery PK applications. Figure 1.10 shows the flowchart... 

Many spectroscopic methods based on the Raman effect, the inelastic scattering of light by molecules, have been developed and employed in various biophysical and bioanalytical applications (1-4). The value inherent in all of these methods lies in the rich information content of Raman spectra due to the dependences of molecular vibrational modes on the chemical and physical microenvironment of the analytes. However, exploiting this information content can be quite challenging due to fiindamental limitations in the sensitivity of the technique and/or practical limitations in the available experimental systems. Much effort has therefore focused on the development of instrumental configurations that endeavor to optimize the utility of the technique for a given application or class of applications. 

A myriad of published reports has now proven the broad and multifaceted applications of modern MS-based techniques for the analysis of small molecules [89-103], Higher-throughput screening has been in demand and will continue to be one of the main objectives of industrial laboratories. However, bioanalytical scientists should bear in mind that the quality of science cannot be compromised at the expense of speed. To this end, poorly developed LC/MS-based methods that lack specificity, sensitivity, and/or ruggedness can lead to erroneous or misleading PK readouts. 

As shown by the applications developed so far, the characteristics of acoustic levitation make it especially suitable for use in analytical and bioanalytical chemistry — however, the earliest applications focused on the determination of mechanical and physical properties of materials such as specific density, viscosity and surface tension [93,115,116]. Ohsaka et al. developed a method for determining the viscosity of highly viscous liquids (particularly, undercooled liquids, which exist at temperatures below their freezing points [117]). Weiser and Apfel used acoustic levitation to measure mechanical properties such as density, compressibility and sound velocity in biological materials [71]. 

Powell ML, Unger SE. Bioanalytical methods challenges and opportunities in drug development. In Applications of Pharmacokinetic Principles in Drug Development. Krishna R, ed. 2004. Kluwer Academic/Plenum Publishers, New York. pp. 21-52. 

As for any bioanalytical method, the extent of validation for an immunoassay should be related to the intended application of the assay. Thus, if an immunoassay is intended to support rapid screening in discovery R D, the characterization of specificity and the accuracy and precision specifications may be less stringent than if the assay is used to support pre-clinical and clinical development studies. Indeed, an assay for discovery support may be designed to detect active metabolites as well as parent molecule, so that... 

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