The first analytical methods for measuring ALCOHOL (ethanol) in blood and other body fluids were developed in the nineteenth century. Although by modern standards these pioneer efforts were fairly crude, they were sufficiently reliable to establish a quantitative relationship between blood-alcohol concentration (BAC) and the various signs and symptoms of inebriation. A significant advance in methodology came in 1922 when Erik M. P. Widmark published his micro-method for analyzing ethanol in specimens of capillary blood.

Blood was drawn by pricking a fingertip or earlobe. The specimen for analysis, 100-150 milligrams, was collected with specially prepared S-shaped glass capillaries that contained a thin film of potassium oxalate and sodium fluoride on the walls of the tube. In Widmark's day, the small amounts (aliquots) of blood needed for each analysis could be measured more accurately by weight than by volume, since constriction pipettes...