On-line solid–phase extraction using a C18 minicolumn coupled to a flow injection system for determination of caffeine in green and roasted coffee beans

Analytical methods applied for the characterization and the determination of bioactive compounds in coffee

“…Other methods used for the determination of caffeine in coffee include UV spectrometry [54,64,65], voltammetry [44,66], gravimetric analysis [54] and paper substrate phosphorescence [67]. As direct measurement of caffeine UV absorbance in water extract of coffee is impossible because of high matrix effects, Balay et al [64] proposed usage of dichloromethane for its extraction before UV measurement.…”

“…Caffeine was determined gravimetrically from evaporated chloroform extract [54]. Another approach to UV analysis was proposed by Salinas-Vargas and Cañizares-Macías who used complicated sample preparation before the measurement [65]. The coffee samples were clarified with the Carrez reagents and then cleaned up using on-line SPE procedure with octadecylsilica cartridge.…”

On-Line Sample Pre-Treatment Procedures Applied to LC–MS

“…126 A thorough understanding of the stationary phase mechanism derived from a chromatographic background will substantially help optimising the retention, washing and elution mechanisms. One obvious difference between the on-line SPE and a chromatography column is the type of samples that are injected.…”

“…The analysis of liquids has also been successfully applied to the detection of a range of organic pollutants including milk, soft drinks and tea. [122][123][124][125][126] The pollutants include xenobiotic compounds that are added directly to the food (such as veterinary drugs, pesticides and herbicides), compounds that leach into the foods from packaging materials (such as bisphenol A 125 ), as well as endogenous compounds, either at a naturally occurring level or where the food has been modified either additively, as in the case of some vitamins, or where it has been removed, as in the case of decaffeinated coffee. 126 …”

Antimicrobial and Antihaemolytic Activities of Crude Extracts of Some Commonly Used Tea and Coffee in Nigeria

“…Caffeine, which is natural alkaloid or xanthine alkaloid, commonly found in coffee beans, tea leaves, cocoa beans and cola nuts have been reported to be the active antimicrobial constituent (Nawrot et al, 2003;Nonthakaew et al, 2015). However, the amount of caffeine varies per plant products and are equally affected by extraction method employed (Guo et al, 2011;Salinas-Vargas et al, 2014). Caffeine evolved as a chemical produced by plants to kill microbes and insect parasites.…”