Extraction of Caffeine from coffee by Homogeneous Liquid-Liquid Micro-extraction (HLLME) method and determination with Spectrophotometer UV-Vis

Caffeine, which stimulates the central nervous system of the human body, is the most popular stimulant all over the world and it is added manually in some products, such as energy drinks. Caffeine is an alkaloid which naturally exists in tea, coffee, cola and cocoa.The extraction of caffeine in coffee has always been a concern for researchers and industry owners. In the homogeneous liquid-liquid micro-extraction, the homogeneous solution contain the sample and the extraction phase. The solution is converted to a two-phase by changing the conditions and its extraction phase precipitates. Recently, the use of mathematical models in the chemical and food industry has been considered to improve performance and increase efficiency. The Response Surface Method (RSM), with the lowest data, can determine the optimal value of several variables simultaneously [1].In this study, homogeneous liquid-liquid micro-extraction (HLLME) and UV spectroscopy method were applied to extract caffeine in coffee and the obtained data was analyzed using RSM. The optimized parameters including extraction pH (3.9), extraction temperature (40 °C) and concentration of extraction phase of triton x-114 (1%) were calculated. The relative standard deviation of 5.0%, the coefficient of correlation of 0.996 and the linear range of 0.1-2 μg.mL-1 of the method were determined. This method has been used to measure caffeine value in coffee.