Peng Xianglu, Brown Melanie, Bowdler Paul, Honeychurch Kevin C
Department of Applied Sciences, University of the West of England, Frenchay Campus, Coldharbour Lane, Bristol BS16 1QY, UK.
Int J Anal Chem. 2020 Apr 1;2020:5405184. doi: 10.1155/2020/5405184. eCollection 2020.
An extraction-free method requiring microliter (L) 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 L 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 g/mL ( = 0.996). The theoretical limit of detection (3 ) was 0.456 g/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.
已开发出一种无需萃取、仅需微升（μL）体积的方法用于测定饮料中的咖啡因。使用热解气相色谱-质谱系统，对直接热脱附-气相色谱-质谱（TD-GC/MS）测定咖啡因所需的条件进行了优化。将5 μL等分试样引入热脱附单元，干燥后热脱附至气相色谱-质谱仪。响应在10至500 μg/mL范围内呈线性（r = 0.996）。理论检测限（3σ）为0.456 μg/mL。未记录到来自饮料内源性成分或常见药物（如尼古丁、布洛芬和对乙酰氨基酚）的干扰。对强化拿铁风味白咖啡和百事极度可乐®中咖啡因的重复测定，平均回收率分别为93.4%（%CV = 4.1%）和95.0%（%CV = 0.98%）。对于一种能量饮料和可口可乐®中咖啡因的规定值，也获得了良好的一致性。这些数据表明该方法在测定此类样品中的咖啡因方面具有前景。
