Automated flow-injection mercurothiocyanate determination of chloride salts of drugs for routine assays: content uniformity and dissolution studies.

An automated flow-injection determination of chloride salts of drugs, based on the colorimetric mercurothiocyanate determination of chloride counterion is described. The majority of these drugs can be determined, using chloride ion standards, with a coefficient of variation less than 1% and a measurement rate of 120 samples per hour. The method is evaluated by determining the interference caused by common inorganic ions, representative organic functional groups, and excipients, and by the analysis of pure drugs and their commercial formulations. The results compare well with those obtained by the official procedures. The benefits of the method are demonstrated in content uniformity tests and in automated monitoring of dissolution studies.