Abstract
An automated iodometric assay, a potential analytical tool for general applications in various quality control and analytical laboratories, was extended for the determination of iodine reactive components in pharmaceutical formulations such as benzylpenicillin. The method was developed based on flow injection analysis (FIA) that utilizes a triiodide (I3-)-selective membrane detector. The principle of the system for penicillin determination was based on the standard iodometric assay, where the penicilloic acid that was produced from the enzymatic hydrolysis reaction was merged and reacted with I3- solutions in the flow system. The excess I3- was then detected by a flow-through potentiometric I3- detector. Under the adopted conditions, a sampling frequency of 75 samples per hour was obtained. The response was linear from 0.05 to 1.0 mmol L-1 and the limit of detection was 0.0025 mmol L-1. Good reproducibility (RSD ±3.80 (n = 4)) was obtained for the determination of 0.5 mmol L-1 benzylpenicillin. Good agreement was obtained between the proposed method and the manufacturer’s claim values when applied to the determination of benzylpenicillin in pharmaceutical formulations.
