title: A rapid and simple determination of caffeine in teas, coffees and eight beverages.
abstract: Caffeine was extracted and preconcentrated by the simple, fast and green method of dispersive liquid-liquid microextraction (DLLME) and analysed by gas chromatography-nitrogen phosphorus detection (GC-NPD). The influence of main parameters affecting the extraction efficiency investigated and optimised. Under the optimal conditions, the method was successfully applied to determination of caffeine in different real samples including five types of tea (green, black, white, oolong teas and tea bag), two kinds of coffee (Nescafe coffee and coffee), and eight beverages (regular Coca Cola, Coca Cola zero, regular Pepsi, Pepsi max, Sprite, 7up, Red Bull and Hype).The limit of detection (LOD) and limit of quantification (LOQ) were 0.02 and 0.05 μg mL(-1), respectively. Linear dynamic range (LDR) was 0.05-500 μg mL(-1) and determination coefficient (R(2)) was 0.9990. The relative standard deviation (RSD) was 3.2% (n=5, C=1 μg mL(-1)).
authors.affiliation: Department of Chemistry, Faculty of Science, University of Tehran, P.O. Box 14155-64555, Tehran, Iran. Electronic address: sereshti@khayam.ut.ac.ir.
authors.forename: Hassan
authors.initials: H
authors.lastname: Sereshti
authors.affiliation: Department of Chemistry, Faculty of Science, University of Tehran, P.O. Box 14155-64555, Tehran, Iran.
authors.forename: Soheila
authors.initials: S
authors.lastname: Samadi
mesh_terms: D001628:Beverages / Q000032:analysis*; D002110:Caffeine / Q000032:analysis*; D002849:Chromatography, Gas / Q000379:methods*; D003069:Coffee / Q000737:chemistry*; D059627:Liquid Phase Microextraction / Q000379:methods*; D013662:Tea / Q000737:chemistry*
chemical_list: D003069:Coffee; D013662:Tea; D002110:Caffeine
keywords: Caffeine; Dispersive liquid–liquid microextraction; Gas chromatography–nitrogen phosphorous detector