Microextraction Recovery of Tilmicosin Phosphate for HPLC-UV Determination in Washings from Surfaces of Pharmaceutical Equipment.

A method for microextraction recovery and concentration of tilmicosin phosphate in washings from surfaces of pharmaceutical equipment for its determination by high-performance liquid chromatography with spectrophotometric detection was proposed. The developed method involved dispersion of the extractant (1-dodecanol) in an aqueous solution of a sample while rotating a cotton disk equipped with an inserted magnetic stirrer followed by crystallization of the extract upon cooling the extraction system. The extractant was applied beforehand to the cotton disk. Effective dispersion of the extractant in the aqueous phase during rotation of the cotton disk ensured a high degree of analyte recovery (94%). The detection limit of tilmicosin phosphate (3σ) reached 0.7 mg/L. The determined concentrations ranged from 2 to 250 mg/L. The analytical capabilities of the developed method were demonstrated using quantitative determination of tilmicosin phosphate in washings from surfaces of pharmaceutical equipment after completion of its cleaning as examples. [ABSTRACT FROM AUTHOR]