Stability bioanalytical applications

Sample collection and preparation are crucial issues for any bioanalytical application in order to address the complexity of samples originating from biological tissues and fluids. It is necessary to cope with the lack in concentration sensitivity typical for capillary separation techniques, to avoid interference from matrix components as well as to ensure analyte stability. In peptide analysis, a strong focus exists on handling small-volume samples and on selective concentration of the analyte in order to overcome limitations with respect to loadability. In addition, loss of analyte frequently occurs due to degradation by proteases and due to adsorption to surfaces, which accordingly needs to be minimized. 

For bioanalytical applications (in vivo or in vitro) high thermodynamic stability, kinetic inertness, and a saturated coordination sphere are required. Given the lability of lanthanide ions (formation of insoluble hydroxides) and their need for high coordination numbers, this poses a real challenge to design an efficient and robust probe therefore, several approach and scaffolds have been used. Most of the... 

The fundamental parameters for bioanalytical validations include accuracy, precision, selectivity, sensitivity, reproducibility, stability of the drug in the matrix under study storage conditions, range, recovery, and response function (see Section 8.2.1). These parameters are also applicable to microbiological and ligand-binding assays. However, these assays possess some unique characteristics that should be considered during method validation, such as selectivity and quantification issues. 

There is a high interest to know the structural features which endow the thermal stability of dioxetanes since this property makes the dioxetane easy to handle and, if accompanied with high chemiluminescence, usable as enzyme label in bioanalytical, clinical application [111]. In this field,... 

Applications of HPLC Of the bioanalytical separation technologies described in this book, arguably HPLC has the widest range of applications, being adopted for the purpose of clinical, environmental, forensic, industrial, pharmaceutical and research analyses. While there are literally thousands of different applications, a few indicators of how HPLC has been used are as follows (i) Clinical quantification of drugs in body fluids (ii) Environmental identification of chemicals in drinking water (iii) Forensic analysis of textile dyes (iv) Industrial stability of compounds in food products (v) Pharmaceutical quality control and shelf-life of a synthetic drug product (vi) Research separation and isolation of components from natural samples from animals and plants. 

The first applications of enzymes in bioanalytical chemistry can be dated back to the middle of nineteenth century, and they were also used for design of first biosensors. These enzymes, which have proved particularly useful in development of biosensors, are able to stabilize the transition state between substrate and its products at the active sites. Enzymes are classified regarding their functions, and the classes of enzymes are relevant to different types of biosensors. The increase in reaction rate that occurs in enzyme-catalyzed reactions may range from several up to e.g. 13 orders of magnitude observed for hydrolysis of urea in the presence of urease. Kinetic properties of enzymes are most commonly expressed by Michaelis constant Ku that corresponds to concentration of substrate required to achieve half of the maximum rate of enzyme-catalyzed reaction. When enzyme is saturated, the reaction rate depends only on the turnover number, i.e., number of substrate molecules reacting per second. 

Applicable principles of GLP should be followed in the conduct of chemical analysis (5). Bioanalytical methods should meet the requirements of specificity, sensitivity, accuracy, precision and reproducibility. Knowledge of the stability of the API and/or its biotransformation product in the sample material is a prerequisite for obtaining reliable results. 

Long term storage stability of analytical samples can be a major issue in several applications, e.g. analysis of pesticide residues in environmental samples and bioanalytical samples. For some validation purposes (e.g. bioanalytical... 

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