Green UHPLC approach for the quantitative determination of tiopronin residues in cleaning validation processes

This study presents the development and validation of a novel reverse-phase ultra-high-performance liquid chromatography (UHPLC) method for quantifying tiopronin residues on manufacturing equipment surfaces as part of cleaning validation. Tiopronin, a synthetic thiol compound with therapeutic applications, requires stringent manufacturing controls to ensure product safety and efficacy. Existing analytical techniques mainly focus on quantifying tiopronin in pharmaceutical formulations or biological matrices. However, no methods specifically address cleaning validation for tiopronin production equipment. Using an Analytical Quality by Design approach, this UHPLC method was optimized and validated by ICH Q2 (R2) guidelines. The technique employs a Waters ACQUITY UPLC H-Class PLUS C-18 column (100 mm × 2.1 mm, 1.7 µm) with a mobile phase of 88:12 (v/v) 0.1% v/v orthophosphoric acid (pH 2.1) and acetonitrile, achieving a tiopronin retention time of 1.3 min. The method demonstrated specificity, precision, accuracy, and linearity over a concentration range of 0.302 to 3.027 µg/mL. The limit of detection and quantification were 0.100 µg/mL and 0.301 µg/mL, respectively. The greenness of the method was assessed using AGREE, GAPI, and RGB 12 tools. The scores obtained were 0.67 for AGREE, 85.0 for BAGI, and 82.1 for RGB 12 suggesting proposed method is environment friendly. This novel method provides an efficient, eco-friendly solution for routine cleaning validation, addressing a significant gap in existing analytical techniques for tiopronin manufacturing.