Abstract
Recently, chromatographic techniques have the potential to be greener in order to reduce the environmental impact. In this work, a new simple, sensitive, efficient, and green analytical method based on UHPLC-MS has been developed for a quick determination of methylxanthines including caffeine, theobromine, and theophylline in tea. Under the optimum conditions, a baseline separation has been achieved within 30 seconds, using isocratic elution consisting of 90% water and only 10% acetonitrile at 0.5 mL/min flow rate (3 mL acetonitrile per hour). The mass spectrometer was operated with the SIR mode in ESI+. The developed method was found to be linear in the range of 0.03–5 μg/mL, with correlation coefficients greater than 0.9995 for the three compounds. The respective values of LOD were found to be 0.025, 0.015, and 0.01 μg/mL for caffeine, theobromine, and theophylline, respectively. The proposed assay was applied to 30 commercial tea samples of different brands. Both caffeine and theobromine were found in all tea samples with maximum concentration in sample no. 15, corresponding to 32.6 and 2.72 mg/g of caffeine and theobromine, respectively. On the contrary, theophylline was not detected at all in most samples. When compared with all previous studies that dealt with the same compounds in different matrices, the developed method was found to be the fastest, allowing high-throughput analyses with more than 100 samples/h. The results prove that the method is suitable for routine analysis of methylxanthines and to distinguish the quality of tea samples of various brands.
Highlights
Nowadays, special interest has been paid to tea extracts because they are the most popular and oldest beverages used all around the world with the exception of water [1]
Full-scan mass spectra of the three compounds were recorded, and the results showed that the highest peak corresponding to the protonated molecular ion has the mass-to-charge ratio of 195.19, 181.164, and 181.164 for caffeine, theobromine, and theophylline, respectively. e identification and quantitation of theobromine, theophylline, and caffeine in the tea samples were accomplished using the selective ion reaction monitoring (SIR) mode
A simple, fast, efficient, cost-effective, and eco-friendly UHPLC-MS method has been developed for the quantitative analysis of caffeine, theobromine, and theophylline components in commercial tea samples of various brands. irty tea samples were investigated, and the average contents of caffeine and theobromine were found to be 24.72 and 1.05 mg/g with limits of detection (LOD) of 0.025 and 0.015 μg/mL, respectively
Summary
Special interest has been paid to tea extracts because they are the most popular and oldest beverages used all around the world with the exception of water [1]. Tea leaves extract may play an important role to prevent chronic gastritis, cardiovascular disease, and arteriosclerosis [8]. It has antioxidant and anticancer activities [9]. Methylxanthines have various physiological effects on the body, including stimulatory effects on the central nervous and respiratory systems [10, 11], bronchial muscle relaxing [11], and gastrointestinal, cardiovascular [12], and myocardial stimulation [13], with increasing blood pressure [14]. High amounts of these substances in human body may cause depression and hyperactivity [17], increased alertness, insomnia, and improvements in learning capacity and exercise performance
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