Determination of Caffeine in Honey by HPLC Coupled with Ultrasound-Assisted Dispersive Liquid-Liquid Microextraction

A method of HPLC combined with ultrasound-assisted dispersive liquid-liquid microextraction was used for the determination of caffeine in honey.The honey sample was dissolved in water to a mass concentration of 500 g·L-1.7.5 mL of the solution was mixed with 150 μL of chloroform and 1.5 mL of methanol by ultrasound for 5 min.The mixture was centrifuged.5 μL of the sedimentary phase was separated on a WondasilTM C18 column using methanol (1+1) solution as the mobile phase for elution.UV detection was made at the wavelength of 274 nm.The linearity range of caffeine was 10.0-500 μg·L-1 with detection limit (3S/N) of 9 μg·L-1.The recovery rates measured by standard addition method ranged from 96.6% to 104%,and the RSD ranged from 2.7% to 4.1%.