. Author manuscript; available in PMC: 2013 Dec 5.

Published in final edited form as: J Agric Food Chem. 2012 Jun 5;60(23):5832–5840. doi: 10.1021/jf3006905

Table 5.

Hydroxybenzoic Acids and Hydrolysable Tannins at 274 nm^a

	position								274 nm

compd	1	2	3	4	5	6	MW	λ_max (nm)	MRRF	MRRF_D	MRRF_P
gallic acid (1)	COOH		OH	OH	OH		170	274	1.00	1.00	1.00
gallic acid (2)	COOH		OH	OH	OH		170	274	0.98		1.00
salicylic acid	COOH	OH					138	302	0.08		0.08
gentisic acid	COOH	OH			OH		154	328	0.04		0.04
protocatechuic acid	COOH		OH	OH			154	260, 294	0.60		0.60
vanillic acid	COOH		OCH₃	OH			168	260, 294	0.79		0.79
2,4,6-trihydroxybenzoic acid	COOH	OH		OH		OH	170	256, 294sh	0.32		0.32
2,3,4-trihydroxybenzoic acid	COOH	OH	OH	OH			170	266	0.95		0.95
syringic acid	COOH		OCH₃	OH	OCH₃		198	276	1.30		1.30

The average moisture content for gallic acid was 2.65% (2.58–2.75% for three determinations). Functional groups: OH, hydroxyl; OCH₃, methoxy; COOH, carboxyl; and no standard for HHDP.