Comprehensive chemical and enantiomeric characterization of commercial turpentine oils by GC-MS

Recent reports from families of individuals with Angelman syndrome (AS), a rare neurodevelopmental disorder characterised by severe neurological impairment and epilepsy, have described perceived neurological improvements following the topical application of a commercial turpentine oil (TO). These observations prompted the present analytical study, which aimed to characterise and quantify the terpenoid composition of 2 commercial TOs (Diamond and Creekwood), together with 6 additional commercial TOs, using gas chromatography-mass spectrometry (GC-MS). Analysis of 6 TOs reported to originate from Pinus pinaster revealed similar combined percentages of α- and β-pinene (≈75%), except for one oil that exhibited a more complex profile, a lower α-pinene content (≈30%), and the presence of eucalyptol, which is uncommon in TOs from this species. The Creekwood oil contained a higher proportion of α-pinene (≈76%) and a markedly lower β-pinene content (≈3%) than the Diamond oil (≈62% and ≈26%, respectively). Chiral GC-MS analysis further revealed contrasting enantiomeric distributions, with (-)-α-pinene predominating in the Diamond oil and (+)-α-pinene in the Creekwood oil, while (-)-β-pinene predominated in both samples. For quantitative analysis, the analytical method was successfully validated, demonstrating suitable detection (1.5-5.0 mg/L) and quantification (5.0-16.7 mg/L) limits, good linearity (r²>0.991), and acceptable precision and accuracy (<15%). These findings demonstrate substantial chemical variability among commercial TOs and provide a framework for future studies on the biological effects of pine resin terpenoids in neuronal models relevant to AS.