Quality Assessment of Citrus limon (L.) Essential Oils Available on the Turkish Market According to European Pharmacopoeia 10.0 Criteria

This study aims to evaluate the compliance of lemon essential oil (LEO) samples available in pharmacies and online platforms in Türkiye with European Pharmacopoeia 10.0 (Ph. Eur. 10.0) standards and provide data regarding product quality in the market. Fourteen distinct commercial LEO samples (five from pharmacies and nine from online platforms) were subjected to physicochemical analyses as outlined in the European Pharmacopoeia (EP), including assessments of appearance, relative density, refractive index, optical rotation, and residue on evaporation. The phytochemical profile of the samples was analyzed using gas chromatography-mass spectrometry (GC-MS) and high performance thin layer chromatography (HPTLC) techniques. The majority of the analyzed samples failed to meet the EP criteria for essential quality attributes, despite their labels as "100% pure." Significant variations detected in the quantities of principal components, such as limonene, citral (neral, geranial), sabinene, and γ-terpinene. Only one sample (A5) successfully passed all pharmacopoeial evaluations. Citropene was not detected in the HPTLC analysis across six samples. Sample A1 failed all GC-MS parameters. Furthermore, certain samples revealed fixed oil residue or post-evaporation residues indicative of possible adulterations. No substantial difference was observed between pharmacy and non-pharmacy channels regarding compliance with the pharmacopoeia. The results indicated inadequacies in quality control and non-adherence to pharmacopoeial requirements for lemon oil products marketed in Türkiye. This circumstance might endanger consumer safety and the possible therapeutic effectiveness of the products. The implementation of quality standards, national reference profiles, and mandated pharmacopoeia analyses might substantially enhance the production of reliable, effective, and verifiable herbal products.