Table 1. Retention times, standard curve slopes and RSD, inter-day RSD, and intra-day RSD for an LC-MS method of analysis for almond skin polyphenols.

Peak, polyphenols		Mol. ion [M-H]−	Rt (min)	Mean slope (n = 18)	Standard slope % RSD	Inter-day % RSD (n = 7)	Intra-day % RSD (n = 3)
(1)	(+)-catechin	289	15.21	4.05E + 06	16	10.3	2.4
(2)	(−)-epicatechin	289	16.46	5.08E + 06	15	10.6	2.7
(3)	procatechuic acid	153	17.37	3.68E + 06	13	7.1	1.3
(4)	p-hydroxybenzoic acid	137	21.67	4.38E + 06	15	5.1	5.8
(5)	quercetin-3-O-rutinoside	609	23.30	1.04E + 07	15	4.1	2.6
(6)	naringenin-7-O-glucoside	433	23.40	7.55E + 06	14	5.2	1.4
(7)	quercetin-3-O-galactosidea	463	23.88	1.23E + 07	16	5.2	2.5
(8)	kaempferol-3-O-galactosideb	447	24.20	NAc	NA	4.3	3.4
(9)	kaempferol-3-O-rutinioside	593	24.52	1.64E + 07	15	5.7	2.0
(10)	dihydrokaempferold	287	25.49	NA	NA	8.1	1.2
(11)	isorhamnetin-3-O-rutinoside	623	25.51	1.07E + 07	15	5.8	1.4
(12)	isorhamnetin-3-O-glucoside	477	25.60	1.69E + 07	14	6.0	2.0
(13)	kaempferol-3-O-glucoside	447	25.67	9.86E + 06	18	6.3	2.4
(14)	eriodictyol	287	25.81	1.17E + 07	17	5.6	3.0
	daidzein (internal standard)	253	27.71	3.81E + 06	16	7.4	3.8
(15)	quercetin	301	30.26	1.07E + 07	25	5.0	1.3
(16)	naringenin	271	30.33	7.37E + 06	14	10.5	2.3
(17)	kaempferol	285	32.27	2.44E + 07	20	9.9	2.8
(18)	isorhamnetin	315	32.53	3.17E + 07	19	6.8	2.4
Average					16	6.8	2.4

^aQuercetin-3-O-galctoside was not resolved from quercetin-3-O-glucoside.

^bKaempferol-3-O-glactoside concentration was determined on the basis of kaempferol-3-O-glucoside equivalents.

^cNA = not applicable.

^dDihydrokaempferol was quantified on the basis of eriodictyol equivalents.