Automated Fluorimetric Assay for Baclofen After On-line Derivatization with o-phthalaldehyde Based on the Sequential Injection Principle

In the present study we report the first automated flow-based derivatization method for the determination of the anti-spastic active pharmaceutical ingredient baclofen. The analyte reacts on-line with o-phthalaldehyde in the presence of N-acetylcysteine in a sequential injection manifold to form a highly fluorescent derivative (340 / 455 nm). The various instrumental (flow rate, volumes of sample and reagents, length of reaction coil) and chemical (pH, amount concentrations of the reagents) variables were carefully investigated. The analytical performance of the proposed method included linearity (5 – 150 % or 1 - 30 mg L-1 baclofen), limits of detection (60 µg L-1) and quantification (200 µg L-1), accuracy, precision and selectivity. Analytical applications involved assay, content uniformity and dissolution studies of baclofencontaining formulations at a sampling throughput of 35-40 h-1.