. Author manuscript; available in PMC: 2008 Aug 30.

Published in final edited form as: Anal Chem. 2007 Apr 5;79(9):3371–3382. doi: 10.1021/ac062397g

Table 1.

Structures and physicochemical properties of the solutes used.

code	Solute	m.w.	pK_a	Log K_o/w	Log K_D
r	new coccine red	C₂₀H₁₁N₂O₁₀S₃Na₃ 604.5	trianion	−5.1	(a)
C	caffeine	C₈H₁₀N₄O₂ 194.2	14.0	−0.07	−0.60
V	vanillin	C₈H₈O₃ 152.2	10.2	1.21	0.15
M	coumarin	C₉H₆O₂ 146.2	n.i.	1.39	0.60
Q	quercetin	C₁₅H₁₀O₇ 302.2	10.3	1.48	0.27
F	ferulic acid	C₁₀H₁₀O₄ 194.2	4.4	1.51	−0.07
U	umbelliferone	C₉H₆O₃ 162.2	10.3	1.58	0.06
Z	salicylic acid	C₇H₆O₃ 138.1	2.9	2.26	0.78
N	naringenin	C₁₅H₁₂O₅ 272.3	10.1	2.52	0.65
O	carvone	C₁₀H₁₄O 150.2	n.i.	3.07	1.38
E	estradiol	C₁₈H₂₄O₂ 272.4	10.5	3.94	1.04
b	β-carotene	C₄₀H₅₆ 537	n.i.	17.6	(b)

n.i. = non ionizable; log K_o/w values were obtained using the Kowwin software (www.syrres.com/esc/est_kowdemo.htm). The Log K_D values were determined in the liquid system hexane/ethyl acetate/methanol/water 4/6/4/6 v/v. a) new coccine red is not retained (K_D = 0); b) β-carotene marks the end of the extrusion step (K_D ∞).