. Author manuscript; available in PMC: 2011 Nov 16.

Published in final edited form as: J Chromatogr A. 2007 Dec 7;1182(1):41–55. doi: 10.1016/j.chroma.2007.11.104

Table 4.

The Total Retention and the Percent Cation Exchange Contribution on ⁻SO₃-HC-C₈ Phases

Stationary Phases	Gradient Washing	[TEAH⁺] (mM)	Retention	Solutes^c
Stationary Phases	Gradient Washing	[TEAH⁺] (mM)	Retention	A	B	C	D	E	F
⁻SO₃-HC-C₈-H	No	120	k’total^a	1.26	1.67	2.07	2.38	3.43	3.98
		120	%k’_IEX^b	100^d	100^d	85	86	81	84
		12	k’total^a	12.82	17.35	17.87	20.75	28.36	33.94
		12	%k’_IEX^b	100	100	98	98	98	98
⁻SO₃-HC-C₈-L	No	20	k’total^a	1.29	1.91	2.04	2.38	3.17	3.92
		20	%k’_IEX^b	91	87	83	83	80	81
		2	k’total^a	11.86	16.85	17.29	20.23	26.05	32.51
		2	%k’_IEX^b	99	99	98	98	98	98
⁻SO₃-HC-C₈-L	Yes	20	k’total^a	1.03	1.50	1.57	1.83	2.38	2.87
		20	%k’_IEX^b	100^d	95	94	92	89	90
		2	k’total^a	10.51	14.33	14.81	17.03	21.51	26.10
		2	%k’_IEX^b	100	100	99	99	99	99

The total retention at different [TEAH⁺ ] calculated from Eq. (5) using the B_IEX and k’_IEX obtained from the linear regression of k’ vs. 1/[TEAH⁺]

The percentage of cation exchange contribution to the total retention at different [TEAH⁺] calculated from Eq. (5) using the B_IEX and k’_IEX obtained from the linear regression of k’ vs. 1/[TEAH⁺]

Solutes: A: morphine; B: hydromorphone; C: cathinone; D: ephedrine; E: 3,4-methylenedioxyamphetamine; F: methamphetamine (see Fig. 3 for the compound structures)

A percentage slightly higher than 100% is obtained because k’_RP is a small negative value, which could be caused by either the error of the linear regression or the very small retention of the dead time marker uracil.