Sequential Injection Lab-at-Valve Micro-Solvent Extraction Assay of Tetracycline

Sequential injection lab-at-valve (SI-LAV) micro-solvent extraction determination procedure for tetracycline hydrochloride in pharmaceutical analysis is proposed. It is based on the formation of a yellow colored ion associate of a protonated cation of tetracycline (TCLN) with anionic form of bromocresol green (BCG), in phthalate buffer pH 4, which could be extracted into dichloromethane. The organic phase is separated from the aqueous phase by means of a conical separating chamber in lab-at-valve unit which placed in one port of the selection valve. An extracted organic layer containing TCLN-BCG associate is monitored by a fiber optic spectrophotometer. The procedure leads to micro-volume analysis. This is a green analytical chemistry. The proposed method was applied to the assay of tetracycline hydrochloride in pharmaceutical samples.