Determination of Propofol in Blood by HPLC Method

Lee, Nan Young; Chang, Soon Hee; Song, Kyung Eun; Lee, Won Kil; Kim, Jay Sik; Kim, Si Oh

Abstract

BACKGROUND
Propofol (2,6-diisopropylphenol) is one of the intravenous anesthetic drugs used for induction and maintenance of general anesthesia as well as for sedation in ICU patients and one-day surgery. The monitoring of propofol in blood helps to maintain anesthetic state and promote earlier recovery. So we attempted to find the rapid and simple method for blood propofol determination.
METHODS
We compared the precipitation method with extraction one using whole blood, plasma and deionized water added a fixed amount of propofol. According to the extraction method, propofol was extracted from 500 microliter sample adding KH2PO4, ethyl acetate, and tetra-ethylammonium hydroxide using thymol as an internal standard. For the precipitation method, the precipitating solution (500 microliter) containing thymol was added to a 500 microliter sample, then mixed. After centrifugation, the supernatant was injected into HPLC system. A Waters 2690 separations module, Waters 474 fluorescence and 486 UV detector and a Symmetry column were used. We used Millennium software to control analyzing process and quantify propofol.
RESULTS
The precipitation method using thymol as an internal standard and Waters 474 fluorescence detector showed the most excellent results. For the calibration curves, we found very good linearity in whole blood, plasma and deionized water (r> or =9976). Intra-assay and inter-assay coefficient of variation (CV) values of propofol for the precipitation method were 4.4% and 8.9% at 2 microgram/mL of propofol and 2.0% and 6.2% at 8 microgram/mL, respectively. The recovery rates of propofol for plasma and whole blood were 104.1% and 92.7% at 2 microgram/mL and 99.4% and 91.6% at 7 microgram/mL, respectively.
CONCLUSIONS
For the measurement of the blood propofol level, the precipitation method using thymol as an internal standard and fluorescence detector seemed to be the rapid and simple method to apply for the clinical purpose.