Optimizing Thermal Pretreatment for Volatile Bioactive Profiling in Medicinal Plants Using HS-GC-MS Analysis

Oregano (Origanum vulgare L.), basil (Ocimum basilicum L.), rosemary (Rosmarinus officinalis L.), yarrow (Achillea millefolium L.), and thyme (Thymus vulgaris L.) are aromatic medicinal plants rich in bioactive volatile compounds with antioxidant, antimicrobial, and anti-inflammatory properties. This study presents a simple, solvent-free, and eco-friendly headspace GC-MS method for VOC profiling. Optimized thermal pretreatment (40–90 °C) enhanced compound detection, particularly at 70–90 °C, without loss of reproducibility. The approach lowers analytical costs and waste generation, supporting green analytical practices and the sustainable valorization of medicinal herbs as natural functional ingredients.