Optimization of capillary electrophoresis-UV absorption detection method for analysis of thymol and carvacrol in essential oil of Thymus serpyllum L

Abstract

Wild Thyme (Thymus serpyllum L.) is a medicinal plant, native to most of Europe. In Lithuania wild thyme usually grows in loam soil and in dry meadows. Wild thyme is often used in herbal medicine and as ingriedient in cooking. Biologically active compounds are most often found in essential oil. About forty-five different chemical compounds where found in essential oil Thymol and carvacrol are two main compounds in essential oil. Both thymol and carvacrol have strong antimicrobial and antifungal properties. Plant material was collected in Utena county. Essential oil extractions were conducted as following: 0.5 grams of dried plant material was extracted for 24 hours in 75% and 100% methanol. Capillary zone electrophoresis method with UV absorption detector was optimized and used for determination of thymol and carvacrol in the extract of Thymus serpyllum L. Optimized conditions were following: 25mM pH=9,35 sodium tetraborate soliution was used as a background electrolyte. 30mM sodium hydroxide solution was used washing the capillary. Applied voltage was 25kV, total capillary length was 60 cm, capillary length to detector was 50 cm, separation temperature was 23°C.