Chemistry Reference
In-Depth Information
OH
OH
O
HO
Levonorgestrel (1)
Ethinylestradiol (2)
1
40°C
40°C
°C
(Step gradient)
→10
10°C
2
(a)
1
2
10°C
(b)
1
40°C
2
(c)
0
10
20
30
40
50
60
Retention time (min)
Figure 20.6
Effect of a temperature change on the retention time of levonorgestrel (1) and ethinylestradiol
(2). HPLC condition: column, P(NIPAAm-
co
-BMA5
%
) modified column (4.6 mm i.d. × 150 mm); mobile phase,
H
O; flow rate, 1.0 ml min
−1
; detection at UV 280 nm, column temperature; (a) step gradient (40°C
→
10°C),
2
(b) 10°C and (c) 40°C.
measure urinary contraceptive drugs. This phenomenon was caused because the PNIPAAm-modified surface
property of the stationary phase changed to hydrophilic at decreased temperature, and the hydrophobic
interaction between the analyte component and the stationary phase was decreased. Additionally, this fact
indicated the effectiveness of 'temperature-responsive' and 'thermo-reversible' properties of a PNIPAAm-
modified surface.
20.6
Affinity chromatography for green bioseparation
Affinity chromatography has been widely used in biomedical research and biotechnology [35]. It is based
on molecular recognition, where one recognition molecule is immobilized on a stationary phase, and the target
molecule can be captured from a crude mixture. The target molecule can then be released from the base
matrix and recovered in a functional form. The fundamental of elution is to decrease the affinity between the
stationary phase and the analyte. A bond-breaking buffer for changing the ionic strength, solvent and pH or
competitive elution is frequently used [36]. There is a serious problem that if a hard elution condition is used,
the target materials undergo degeneration. For this reason, temperature-responsive chromatography, which is
