Rapid and Sensitive Determination of Methylxanthines in Commercial Brands of Tea Using Ultra-High-Performance Liquid Chromatography-Mass Spectrometry

Table 1

The average content of theobromine, theophylline, and caffeine (mg/g ± %RSD) (n = 5) in commercial tea samples.

Sample no.	Concentration (mg/g ± %RSD)
	Theobromine	Theophylline	Caffeine
1	0.27 ± 0.25	0.14 ± 2.61	13.30 ± 1.68
2	1.22 ± 2.66	ND	27.58 ± 1.63
3	0.44 ± 0.55	Traces	17.06 ± 1.24
4	0.41 ± 2.64	Traces	23.15 ± 2.32
5	1.16 ± 2.84	ND	27.95 ± 2.79
6	0.55 ± 1.55	ND	23.29 ± 2.05
7	0.63 ± 0.47	ND	18.37 ± 1.99
8	0.99 ± 4.08	ND	25.90 ± 2.58
9	0.63 ± 0.77	ND	20.96 ± 2.51
10	1.39 ± 3.39	ND	29.16 ± 2.45
11	0.86 ± 2.11	ND	23.48 ± 1.17
12	0.85 ± 3.03	Traces	26.32 ± 2.32
13	1.16 ± 0.95	Traces	25.32 ± 0.83
14	1.76 ± 2.40	ND	27.33 ± 1.67
15	2.72 ± 1.69	ND	32.61 ± 0.81
16	1.18 ± 2.26	ND	26.99 ± 1.54
17	1.73 ± 3.23	ND	26.63 ± 3.02
18	1.15 ± 1.87	ND	27.58 ± 1.23
19	1.01 ± 3.36	ND	25.83 ± 3.14
20	0.57 ± 2.66	ND	20.09 ± 2.56
21	0.44 ± 1.13	Traces	22.55 ± 1.92
22	0.50 ± 1.31	Traces	22.51 ± 3.03
23	0.20 ± 0.48	ND	16.11 ± 0.81
24	1.99 ± 2.97	ND	29.70 ± 3.02
25	1.10 ± 2.51	ND	21.06 ± 2.98
26	0.86 ± 2.45	ND	30.30 ± 1.67
27	2.34 ± 2.00	ND	32.34 ± 2.78
28	0.49 ± 1.51	ND	22.33 ± 2.86
29	2.10 ± 3.30	ND	31.84 ± 2.78
30	0.72 ± 1.19	ND	23.84 ± 1.85