Extraction-free, direct determination of caffeine in microliter volumes of beverages by thermal desorption-gas chromatography mass spectrometry

Peng, Xianglu; Brown, Melanie; Bowdler, Paul; Honeychurch, Kevin C.

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. *e response was linear over the range 10 to 500 μg/mL
(R2 = 0.996). *e 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®. *ese
data suggest that the method holds promise for the determination of caffeine in such samples.

• Journal Article Type: Article
• Acceptance Date: Mar 2, 2020
• Online Publication Date: Apr 1, 2020
• Publication Date: Apr 1, 2020
• Deposit Date: Apr 2, 2020
• Publicly Available Date: Apr 2, 2020
• Journal: International Journal of Analytical Chemistry
• Print ISSN: 1687-8760
• Electronic ISSN: 1687-8779
• Publisher: Hindawi
• Peer Reviewed: Peer Reviewed
• Volume: 2020
• Article Number: 5405184
• Pages: 1-7
• DOI: https://doi.org/10.1155/2020/5405184
• Keywords: Analytical Chemistry
• Public URL: https://uwe-repository.worktribe.com/output/5849868