title: Fully-automated in-syringe dispersive liquid-liquid microextraction for the determination of caffeine in coffee beverages.
abstract: 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.
authors.affiliation: Department of Chemistry, University of the Balearic Islands, Carretera de Valldemosa km 7.5, 07122 Palma de Mallorca, Spain.
authors.forename: Rejane M
authors.initials: RM
authors.lastname: Frizzarin
authors.affiliation: Department of Chemistry, University of the Balearic Islands, Carretera de Valldemosa km 7.5, 07122 Palma de Mallorca, Spain.
authors.forename: Fernando
authors.initials: F
authors.lastname: Maya
authors.affiliation: Department of Chemistry, University of the Balearic Islands, Carretera de Valldemosa km 7.5, 07122 Palma de Mallorca, Spain.
authors.forename: José M
authors.initials: JM
authors.lastname: Estela
authors.affiliation: Department of Chemistry, University of the Balearic Islands, Carretera de Valldemosa km 7.5, 07122 Palma de Mallorca, Spain. Electronic address: victor.cerda@uib.es.
authors.forename: Víctor
authors.initials: V
authors.lastname: Cerdà
mesh_terms: D001331:Automation; D001628:Beverages / Q000032:analysis*; D002110:Caffeine / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D003069:Coffee / Q000737:chemistry*; D059627:Liquid Phase Microextraction / Q000379:methods*; D012997:Solvents / Q000737:chemistry; D013594:Syringes
chemical_list: D003069:Coffee; D012997:Solvents; D002110:Caffeine
keywords: Caffeine determination; Coffee beverages; Dispersive liquid-liquid microextraction; Lab-in-syringe; Spectrophotometry; UV detection