TABLE 1.

MRM parameters of 28 target compounds detected on the UPLC–MS/MS.

NO.	Analytes	RT (min)	Precursor ion (m/z)	Product ion (m/z)	DP (V)	EP (V)	CE (V)	CXP (V)
1	Uracil	1.82	112.959	70.1	101	10	21	8
2	Guanine	3.09	152.040	109.9	111	10	27	12
3	2′-deoxythymidine	1.17	243.052	126.9	11	10	13	14
4	2′-deoxyadenosine	1.57	252.021	136.0	26	10	19	14
5	Uridine	1.81	245.119	113.0	21	10	13	12
6	Adenosine	1.91	268.023	136.1	31	10	23	14
7	2′-deoxyinosine	1.98	253.024	136.9	11	10	11	16
8	2′-deoxycytidine	2.70	228.034	112.1	1	10	11	12
9	2′-deoxyguanosine	3.09	268.066	152.0	11	10	13	16
10	Cytidine	3.66	244.161	112.0	31	10	15	12
11	Guanosine	4.35	284.056	152.0	1	10	17	16
12	cAMP	7.46	329.971	136.0	121	10	31	16
13	cGMP	9.55	345.954	152.0	96	10	25	18
14	Leucine	3.87	132.069	86.2	11	10	13	10
15	Phenylalanine	3.88	166.097	120.1	1	10	17	14
16	Tryptophan	4.11	205.089	146.1	26	10	25	16
17	Isoleucine	4.32	132.069	69.0	11	10	25	8
18	Methionine	5.04	150.117	104.0	36	10	15	12
19	Valine	5.55	118.125	72.0	1	10	13	8
20	Threonine	8.69	120.128	74.0	16	10	13	8
21	Lysine	16.51	147.110	84.0	61	10	23	10
22	Proline	5.64	116.167	70.0	21	10	19	10
23	Tyrosine	6.24	182.097	136.1	41	10	19	16
24	Glutamate	9.76	148.051	84.1	66	10	21	10
25	Glutamine	10.07	147.072	84.1	51	10	23	10
26	Asparagine	10.48	133.111	87.1	1	10	13	10
27	Arginine	16.29	175.110	70.1	86	10	27	8
28	GABA	4.34	104.022	87.1	1	10	17	52