Table 2.

Validation of the tentatively identified phenolic compounds using their standards on UPLC-QTOF-MS/MS.

Phenolic compound	Exact mass	aExpt. mass	Slope	Intercept	bR2	cLOD (ng/ml)	dLOQ (ng/ml)	Precursor ion mass	eMS/MS
Vanillic acid	168.0422	167.0422	8.377	−170.350	0.9614	0.3	0.4	167	167, 152, 123, 108
Vanillin	152.0473	151.0473	53.105	−19.293	0.9985	0.2	0.4	151	151, 136, 108, 92
Ferulic acid	194.0579	193.0579	113.846	2442.610	0.9349	0.3	0.4	193	193, 178, 134
p-Coumaric acid	164.0473	163.0473	244.990	859.603	0.9956	0.3	0.4	163	163, 119, 93
Caffeic acid	180.0422	179.0422	1120.833	−2045.589	0.9996	0.2	0.4	179	179, 135, 89
Quercetin	302.0426	301.0426	1052.024	3.418	0.9892	0.3	0.4	301	301, 273, 178, 151
Rutin	610.1533	609.1533	819.436	2068.880	0.9960	0.3	0.4	609	609, 301, 271
Salicylic acid	138.0316	137.0316	96.887	8378.975	0.9992	0.1	0.3	137	137, 93
Chlorogenic acid	354.0950	353.0950	550.314	1604.424	0.9983	0.2	0.4	353	353, 263, 190, 146, 102
2,4-dihydroxybenzoic acid	154.0266	153.0266	86.953	−511.931	0.9982	0.2	0.3	153	153, 108
Nobiletin	402.1314	401.1314	13.610	−48.786	0.9995	0.6	1.0	401	401, 341, 189
Hesperidin*	610.1897	611.1897	1455.044	553.506	0.9948	0.6	0.8	611	611, 465, 303
Sinapic acid*	224.0684	225.0684	37.385	−35.751	0.9974	0.6	0.8	223	223, 208, 193, 149, 121
p-hydroxybenzoic acid*	138.0316	139.0316	13.630	49.741	0.9982	0.5	1.0	139	139, 121, 99, 75

^aExperimental mass that was obtained after addition or deletion of H⁺ or H⁻ ion;

^bR², coefficient of determination obtained through regression analysis;

^cLOD, Limit of detection;

^dLOQ, Limit of quantitation;

^eMS/MS, mass of the ions produced from fragmentation of precursor ion; Phenolic compounds were detected in negative mode of ionization except the compounds marked with

^“*”in positive mode of ionization.