Pine turpentine essential oil (PTEO) obtained from Pinus pinaster Ait. is known to be used in many fields such as medicine, cosmetics, agriculture, and art. The medicinal use of essential oils puts pressure on industry to produce high-quality products. Pure essential oils derived from natural sources are mistakenly recognized as safe on the grounds of their natural origin. Unless they meet international standards, their safety remains questionable. Therefore, in this study, it was aimed to evaluate the quality of 14 different pine turpentine essential oil samples purchased from various sources on the Turkish market, based on the legally recognized pharmacopoeia in Türkiye, the European Pharmacopoeia (EP). As stated in the “Turpentine Oil” monograph, appearance, relative density, refractive index, optical rotation, acid value, peroxide value, fatty oils, and resinified essential oils analyses were performed for each sample. Additionally, phytochemical profiles were analyzed by high performance thin-layer chromatography (HPTLC) and gas chromatography-mass spectrometry (GC-MS). The results revealed that none of the samples were compliant with EP standards. With this in mind, it is found necessary to impose strict regulations on the production of commercial essential oils. Nevertheless, pharmacies emerge as preferable options for obtaining such products.

Essential oils are mixtures of complex secondary metabolites with variable chemical compositions that determine their therapeutic effects. Thyme oil, obtained from the fresh or dried leaves and flowers of Thymus spp. through steam distillation, is widely used in food, pharmacy, and perfumery–cosmetics due to its antimicrobial, antitussive, and antioxidant properties. Ensuring the quality of essential oils is important for public health, as globally encountered deviations from the established standards pose a risk to consumers. This study evaluated the quality of 12 different Thymus vulgaris L. essential oil (TVEO) samples from pharmacies and various sources on the Turkish market, focusing on their adherence to the European Pharmacopoeia (EP) 10.0. Following primary assessments of appearance, solubility, relative density and refractive index; high-performance thin-layer chromatography (HPTLC) and gas chromatography–mass spectrometry (GC-MS) analyses were performed for each TVEO sample to profile their phytochemical composition. Results revealed that none of the samples met all the criteria specified in EP 10.0. The mean proportion of EP criteria fulfilled per sample is 46.9% for pharmacy-sourced samples and 41.9% for non-pharmacy-sourced samples. The findings of this study suggest that future quality control analysis for TVEO samples on the Turkish market should integrate comprehensive chemical profiling with advanced analytical strategies.