Toxicology testing in alternative specimen matrices

Most toxicology testing involves serum, blood, or urine. Sampling from a site of action such as nerve endings or receptors on cells is not usually available, so often blood is used. Plasma and serum are logical sources to monitor without the interference of red cells. Other types of specimens may be tested and may even be required. Most of such testing has become possible as a result of newer instrumentation. Many of these alternative specimens have very low concentrations of the drugs, drug metabolites, or other toxins. Liquid chromatography-tandem mass spectrometry has allowed testing of these alternative specimens.