Clinical Chemistry, Vol 7, 285-291, Copyright © 1961 by the American Association for Clinical Chemistry

Automatic Titration with Direct Read-out of Chloride Concentration

¹ Laboratory of Kidney and Electrolyte Metabolism, National Heart Institute, and the Clinical Chemistry Service, Clinical Pathology Department, Clinical Center, National Institutes of Health, Bethesda 14, Md.

Direct read-out of chloride concentration is provided by an auxiliary designed for use with the automatic coulometric-amperometric titrator of Cotlove 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 min. 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 solutions with lower concentrations down to 1 mEq./L.). Optimal accuracy with a 0.1-ml. sample was in the concentration range above 40 mEq./L., in which the coefficient of variation was about ± 0.5 per cent.