Determination of Submicrogram-per-Liter Concentrations of Caffeine in Surface Water and Groundwater Samples by Solid-Phase Extraction and Liquid Chromatography

Abstract

A method for determining submicrogram-per-liter concentrations of caffeine in surface water and groundwater samples has been developed. Caffeine is extracted from a 1 L water sample with a 0.5 g graphitized carbon-based solid-phase cartridge, eluted with methylene chloride-methanol (80 + 20, v/v), and analyzed by liquid chromatography with photodiode-array detection. The single-operator method detection limit for organic-free water samples was 0.02 μg/L. Mean recoveries and relative standard deviations were 93 ± 13% for organic- free water samples fortified at 0.04 μg/L and 84 ± 4% for laboratory reagent spikes fortified at 0.5 μg/L. Environmental concentrations of caffeine ranged from 0.003 to 1.44 μg/L in surface water samples and from 0.01 to 0.08 μg/L in groundwater samples.

Sensitive analysis of trace caffeine in human serum by HPLC using tetraazacalix[2]arene[2]triazine-modified silica as SPE sorbent

“…For the sake of overcoming these disadvantages, SPE has been developed and applied in the determination of the concentration of caffeine in tobacco products, smokers' urine and blood. [32][33][34][35][36][37][38][39] Conventional SPE methods, employing RP or ion-exchange sorbents, demonstrate indiscriminate adsorption effects, so that large amounts of matrix interference are extracted simultaneously with caffeine, which inuences the accuracy of the determination. Also, bonded silica gel and organic polymer SPE materials can't meet the requirements of enriching specic samples due to single interaction models, such as PS-DVB, C18 and C8, which only retain solutes through the hydrophobic effect, bonded amino silica gels rely on weak anion exchange or polarity adsorption to reach the effect.…”