Sustainable miniaturized smartphone-coupled TLC platform for innovative cleaning validation: application to tizanidine combinations under challenging concentration ratios.

Cross-contamination in pharmaceutical industry is a critical threat to patient safety, potentially reducing therapeutic efficacy and causing adverse effects and addiction. Drugs with narrow therapeutic index and high abuse potential are high-risk candidates, such as tizanidine (TZN). Its carryover may trigger harmful effects, withdrawal symptoms, and unintended dependence. Although cleaning validation minimizes these risks, rapid and reliable tools are still needed to support routine monitoring. To address this need, a portable at-line analytical platform was developed for TZN determination in combination with aceclofenac (ACF), ibuprofen (IBF), and paracetamol (PRC). It employs FDA-recommended swabbing approach, followed by smartphone-based TLC coupled with Color Analyzer and ImageJ for image processing. It provides a rapid, simple, and eco-friendly on-site tool for cleaning validation, enabling both quantitative analysis and qualitative screening via color density charts; a combination not achieved by reported methods. The mobile phase was optimized as toluene-acetone-ethanol (2.3:2.7:0.6 v/v/v), and smartphone-based analysis parameters were optimized. Validation according to ICH guidelines demonstrated good linearity and high sensitivity for the investigated drugs, with quantitation limits below established acceptance limits. Multidimensional sustainability was confirmed using moGAPI, CACI, VIGI, and RGB-12 assessments, highlighting the method as a novel sustainable tool for reliable cleaning validation of TZN combinations.