Basic principles involved in the operation of instruments commonly found in analytical laboratories. Included are absorption spectrometers (atomic absorption, etc) emission spectrometers (arc, ICP and DCP), X-ray fluorescence spectrometer, electrochemical instruments (polarography, anodic stripping, coulometry, ion selective electrodes) and fluorometer. The description and function of the various instrument components will be presented to assist in discussions about the relative advantages and disadvantages of an instrument for a given analytical problem, errors and error avoidance, and instrument calibration.