Comparison of two methods to quantify 2,6-dichlorophenol from tick Amblyomma cajennense by GC/MS-SIM

Abstract

Amblyomma cajennense (Acari: Ixodidae) is a tick of socioeconomic importance in the South American sub-continent. Nevertheless, little is known pertaining to its chemical ecology, information deemed crucial to its management. In this study, the tick sex pheromone 2,6-dichlorophenol (2,6-DCP) was quantified from A. cajennense fed on rabbits for 6 days by use of gas chromatography-mass spectrometry in the selected ion monitoring mode (GC/MS-SIM). The sex pheromone extract was obtained by the exposure of attractive females to hexane and ultrasound probe in two independent samples. Clean-up was not necessary. Standard addition method (SA) and calibration curve with 5-bromine-4-hydroxy-3-methoxybenzaldehyde (5-BrV) as an internal standard (IS) were employed in the quantification. 2,6-DCP contents did not show significant differences between extracts and/or methods. Results showed that the concentration range of sex pheromone per female were 2.03-2.27 ng mL-1 and 2.06-2.24 ng mL-1 for SA and IS methods, respectively. The methods provide a specific, sensitive and reliable technique for determining 2,6-DCP levels in ticks.