title: Chemical analysis of marker substances.
abstract: The development of chemical assay procedures for potential marker substances will depend on, and be determined by, three basic factors: (1) the nature of the substance used, (2) the characteristics of the biological samples obtained, and (3) the varieties of information required. Once these have been delineated, the analytical methodology can be specifically characterized in terms of specificity and sensitivity; accuracy, precision, and reliability; and ease, cost, and safety. The specific details of a method must be based on the three factors mentioned above. Thus, a procedure having an ultimate sensitivity limit of more than a micromole per milliliter will be useless if the maximum expected marker concentration in the sample is less than a micromole per milliliter. Similarly, a procedure utilizing gas-liquid chromatography mass spectrometry costing many thousands of dollars is overkill if only a simple, inexpensive thin-layer chromatography procedure is needed to merely confirm the presence of the marker in a sample of urine or blood. Finally, the potential utility of the marker substance will be constrained by nonscientific factors such as cost, time, and convenience. These factors may depend on the ultimate applications of marker substance use, but they must also be addressed in any assay development program. The overall characteristics of a chemical assay procedure for marker substances will be discussed in terms of a model based on similar procedures for the chemical assay of foreign organic compounds in biological materials.
mesh_terms: D003365:Costs and Cost Analysis; D006801:Humans; D010349:Patient Compliance; D004364:Pharmaceutical Preparations / Q000032:analysis* / Q000652:urine; D013048:Specimen Handling
chemical_list: D004364:Pharmaceutical Preparations