Abstract
An extraction-free method requiring microliter (μL) volumes has been developed for the determination of caffeine in beverages. Using a pyrolysis-gas chromatography mass spectrometry system, the conditions required for the direct thermal desorption-gas chromatography mass spectrometry (TD-GC/MS) determination of caffeine were optimised. A 5 μL aliquot was introduced to the thermal desorption unit, dried, and thermally desorbed to the GC/MS. The response was linear over the range 10 to 500 μg/mL (R2 = 0.996). The theoretical limit of detection (3 σ) was 0.456 μg/mL. No interferences were recorded from endogenous beverage components or from commonly occurring drugs, such as nicotine, ibuprofen, and paracetamol. Replicate caffeine determinations on fortified latte style white coffee and Pepsi Max® gave mean recoveries of 93.4% (%CV = 4.1%) and 95.0% (%CV = 0.98%), respectively. Good agreement was also obtained with the stated values of caffeine for an energy drink and for Coca-Cola®. These data suggest that the method holds promise for the determination of caffeine in such samples.
Highlights
Caffeine is one of the most commonly consumed drugs, with a long history of usage [1], being commonly used to improve mental alertness and alleviate fatigue
It has been found to give a number of both beneficial and adverse effects on a wide range of conditions [2]. It is naturally found in a number of commonly consumed beverages such as in tea, coffee, and chocolate and is commonly added to a wide range of both alcoholic and nonalcoholic drinks, medicines [3], and cosmetics [4] and is present in some electronic cigarette e-liquids [5]
It is reported that the majority of people regularly consumes caffeine [6, 7], and coffee has been reported as the second most commonly consumed drink after water [8]. e prevalence of caffeine in the society has recently been highlighted by its occurrence in the majority of human blood donations [9]
Summary
Caffeine is one of the most commonly consumed drugs, with a long history of usage [1], being commonly used to improve mental alertness and alleviate fatigue. It has been found to give a number of both beneficial and adverse effects on a wide range of conditions [2]. It is naturally found in a number of commonly consumed beverages such as in tea, coffee, and chocolate and is commonly added to a wide range of both alcoholic and nonalcoholic drinks, medicines [3], and cosmetics [4] and is present in some electronic cigarette e-liquids [5]. Caffeine is one of the few drugs allowed in sport; its beneficial effects in disciplines that require endurance, such as cycling [10], triathlon [11], and soccer [12], have been reported. A number of deaths have been reported [19,20,21]
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