Chemistry Reference
In-Depth Information
3.0
LCST 32°C
2.5
2.0
1.5
1.0
0.5
0
-0.5
3.0
3.1
3.2
3.3
3.4
3.5
3.6
3.7
1/
T
x 10
3
Figure 20.4
The van't Hoff plots for five steroids on PNIPAAm modified HPLC column. Hydrocortisone
(closed circle), prednisolone (open circle), dexamethasone (closed triangle), hydrocortisone acetate (open
triangle) and testosterone (closed square).
agent in a biological sample. We introduced two applications of temperature-responsive chromatography to
biological analysis. First, an anesthetic agent propofol was analyzed by isocratic elution. Second, contraceptive
drugs were analyzed by temperature-gradient elution.
20.5.1
Analysis of propofol in plasma using water as a mobile phase
Propofol (2,6-diisopropylphenol) is an intravenous anesthetic agent that is used for both the induction and
maintenance of anesthesia [31]. Moreover, it is widely used during minor surgery of laboratory animals.
Because a low propofol dosage causes intraoperative awaking, monitoring of the anesthetic agent level during
anesthesia or sedation is very important. We developed a HPLC-fluorescent detection (HPLC-FL) method
utilizing a temperature-responsive chromatography system for the analysis of propofol, and evaluated its
performance compared to the RPLC method [32] (Figure 20.5). Drug administrated monkey serum (80
l)
was used as the biological sample. To the serum was added methanol containing thymol, which was used as
an internal standard. The mixture was purified using a C18 pretreatment cartridge. After washing with H
2
O,
the target analyte was eluted with methanol. The recovery rate of propofol during the simple pretreatment was
about 80
μ
. P(NIPAAm-
co
-BMA) copolymer was used as a stationary phase. The obtained calibration rage
was covered from 0.5
%
g ml
−1
, and allowed a reproducible quantification of the serum propofol.
The relative standard deviations of intra- and inter-assay were below than 15
μ
g ml
−1
to 10
μ
. In addition, there was a good
relationship of the quantification values between the temperature-responsive chromatography and the
conventional RPLC method. Because the developed method used only water as the mobile phase, there were
some advantages in conducting the TDM. First, the avoidance of complicated mobile phase preparation was
possible, which was important for busy medical staff members to reduce their work. Second, the developed
method could solve the problem related to waste solutions and the exposure of patients to harmful organic
solvents, which occurs when using RPLC.
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