Automatic titration with direct read-out of chloride concentration.

Direct read-out of chloride concentration is provided by an auxiliary designed for use with the automatic coulometric-amperometric titrator of Cotiove et al. (1). The circuitry, construction, and operation of the auxiliary are described. Automatic titration of samples of biologic fluids such as serum, cerebrospinal fluid, urine, sweat, and gastrointestinal fluids requires no prior preparation and the usual titration is completed within 1 mm. The chloride concentration of the sample appears on a digital register directly in milliequivalents per liter. In routine use by various technologists in a clinical chemistry laboratory, the auxiliary-titrator combination has proved to be simple to operate and consistently accurate. The procedure requires only 0.1 ml. of solutions containing 10-400 mEq./L. of chloride (or 1 ml. of solutionswith lower concentrationsdown to 1 mEq./L.). Optimal accuracy with a 0.1-mi. sample was in the concentration range above 40 mEq./L., in which the coefficient of variation was about ± 0.5 per cent.