Photochemical derivatization and spectrophotometric determination of thioridazine by flow injection

A flow-injection manifold is proposed for the on-line photochemical derivatization of thioridazine hydrochloride. The phodegradation is carried out in the coil of the injection valve, constituted of a PTFE tubing helically coiled around a UV lamp. Aqueous nitric acid was used as the carrier stream. The calibration graph is linear over the range 7.5–60 mg ml−1 in a flow-cell of 10 mm light-path (5.0–40 mg ml−1 in a 50.0 mm flow-cell) with an RSD over the range 1.5–2.1% for 10–40 μg ml−1 and a sample throughput of 90 h−1. The influence of foreign compounds is studied. The procedure is applied to the determination of thioridazine hydrochloride in pharmaceutical formulations.