Bioanalysis is a sub-discipline of analytical chemistry covering the quantitative measurement of xenobiotics (drugs and their metabolites, and biological molecules in unnatural locations or concentrations) and biotics (macromolecules, proteins, DNA, large molecule drugs, metabolites) in biological systems.
Bioanalysis also applies to drugs used for illicit purposes, forensic investigations, anti-doping testing in sports, and environmental concerns.
However, the past twenty years has seen an increase in biopharmaceuticals (e.g. proteins and peptides), which have been developed to address many of the same diseases as small molecules.
[1] The first studies measuring drugs in biological fluids were carried out to determine possible overdosing as part of the new science of forensic medicine/toxicology.
As such, automated sample preparation methods and liquid-handling robots are commonly employed to increase efficiency and reduce costs.