Development of a validated HS-GC-MS analytical method for the quantification of linalool oxide isomers in nanostructured formulations

Linalool oxide (LOX) is a monoterpenoid found in the essential oils of various plants and can be obtained from linalool, which is used in traditional medicine as a sedative, analgesic, anxiolytic and hypnotic. Unlike linalool, there are few published studies on LOX and its isomers. Nanoformulations based on a mixture of cis and trans isomers in the furanoid form of LOX indicated for the treatment of pain and inflammation were analyzed in an analytical method using Gas Chromatography coupled to Mass Spectrometry with Headspace Sampling (HS-GC-MS). The method followed the parameters described in the International Council on Harmonization, Validation of Analytical Procedures (ICH) with regard to specificity, linearity, precision and accuracy. The method developed was linear in the range of 1–25 ppm for the mixture of isomers (R² > 0.99), with high precision and accuracy. The limit of detection values for LOX isomers 1 and 2 were 1.22 μg mL⁻¹ and 0.51 μg mL⁻¹, respectively. The limit of quantification values for LOX isomers 1 and 2 were 3.71 μg mL⁻¹ and 1.54 μg mL⁻¹, respectively. The content of LOX isomers in the nanoemulgels was 11.05 % (w/w) for the formulation with carbopol 940 gel (F-LOX-G) and 11.04 % (w/w) for the formulation without carbopol gel (F-LOX).