Rapid HPLC methods for the analysis of the oxygen heterocyclic fraction in citrus essential oils.

Two different HPLC methods were developed to determine the oxygen heterocyclic compounds in citrus essential oils. Five different citrus essential oils (lemon, bergamot, mandarin, sweet orange and bitter orange) were analyzed under identical conditions by reversed phase (RP) HPLC with Photodiode Array detector (PDA), for a direct comparison of the composition of their oxygen heterocyclic fraction. One method (A) was developed on a conventional C18 column (15 cm x 4.6 mm, 5 mum p.s.), while a "fast" (3 cm x 4.6 mm, 3 mum p.s.) C18 column was used for the second method (B). Once method A was optimized, pH effect was also evaluated both on separation efficiency and peak symmetry. Both the developed methods were found to be suitable for the direct comparison of the five oils. Method A gave good separation in sixteen minutes. Method B, gave lower resolution, but was suitable for rapid screening or fingerprinting of the oil and fast direct comparison of the five different oils, with sufficient separation being obtained in less than eight minutes.