Optimization of headspace solid-phase microextraction for analysis of β-caryophyllene in a nanoemulsion dosage form prepared with copaiba (Copaifera multijuga Hayne) oil

Recent studies have shown the anti-inflammatory activity of Copaiba oils may be addressed to the high content of beta-caryophyllene, the most common sesquiterpene detected, especially in the Copaifera multijuga Hayne species. In the present study, nanoemulsions were proposed as a delivery system for copaiba oil in view to treat locally inflamed skin. This article describes the optimization and validation of a stability-indicating SPME-GC method, for beta-caryophyllene analysis in the nanoemulsions produced by high pressure homogenization. SPME methods are performed with PDMS (polydimethylsiloxane) fiber (100 mu m). Three SPME parameters were evaluated by a three-level-three-factor Box-Behnken factorial design as potentially affecting the technique efficiency. According to the results obtained, the best conditions to extract beta-caryophyllene were: (i) sampling temperature of 45 degrees C, (ii) sampling time of 20 min and (iii) no NaCl addition. Results coming from the forced degradation tests showed a reduction of beta-caryophyllene peak area when both caryophyllene methanolic solution and nanoemulsions were exposed to acid hydrolysis. UV-A irradiation, oxidative (H2O2) and thermolitic (60 degrees C) conditions. Such reduction occurred in lower extent in the nanoemulsions, suggesting a protective effect of the formulation to beta-caryophyllene content. Since no degradation products were detected in the same retention time of beta-caryophyllene, the specificity of the method was demonstrated. The method was linear in the range of 0.14-0.68 mu g mL(-1) of beta-caryophyllene (r(2) > 0.999), and was also validated for precision (R.S.D. <= 5.0%), accuracy (97.85-101.87%) and robustness. Finally, the method was applied to quantification of beta-caryophyllene content in the developed formulations. (C) 2012 Elsevier B.V. All rights reserved.