Fully-automated in-syringe dispersive liquid-liquid microextraction for the determination of caffeine in coffee beverages

• Published in: Food chemistry 2016-12, Vol.212, p.759-767
• Main Authors: Frizzarin, Rejane M., Maya, Fernando, Estela, José M., Cerdà, Víctor
• Format: Article
• Language: English
• Subjects: Automation; Beverages - analysis; Caffeine - analysis; Caffeine determination; Chromatography, High Pressure Liquid - methods; Coffee - chemistry; Coffee beverages; Dispersive liquid-liquid microextraction; Lab-in-syringe; Liquid Phase Microextraction - methods; Solvents - chemistry; Spectrophotometry; Syringes; UV detection
• ISSN: 0308-8146; 1873-7072
• DOI: 10.1016/j.foodchem.2016.06.032

•Automated dispersive liquid-liquid microextraction.•In-syringe stirring for enhanced extraction.•Determination of caffeine in coffee beverages.•Fast and simple procedure for automated analysis in beverages. A novel fully-automated magnetic stirring-assisted lab-in-syringe analytical procedure has been developed for the fast and efficient dispersive liquid-liquid microextraction (DLLME) of caffeine in coffee beverages. The procedure is based on the microextraction of caffeine with a minute amount of dichloromethane, isolating caffeine from the sample matrix with no further sample pretreatment. Selection of the relevant extraction parameters such as the dispersive solvent, proportion of aqueous/organic phase, pH and flow rates have been carefully evaluated. Caffeine quantification was linear from 2 to 75mgL−1, with detection and quantification limits of 0.46mgL−1 and 1.54mgL−1, respectively. A coefficient of variation (n=8; 5mgL−1) of a 2.1% and a sampling rate of 16h−1, were obtained. The procedure was satisfactorily applied to the determination of caffeine in brewed, instant and decaf coffee samples, being the results for the sample analysis validated using high-performance liquid chromatography.