Application of 3-(1,8-Naphthalimido) Propyl-Modified Silyl Silica Gel as a Stationary Phase In High Performanc Liquid Chromatography of Barbiturates and Diastereomeric Compounds

Abstract

Abstract The application of a column packing material, 3-(l,8-naphthalimido)propyl-modified silyl silica gel (NAIP) developed by us, for high performance liquid chromatography (HPLC) of barbiturates and diastereomeric compounds is described. The separation of barbiturates by using an NAIP column as a stationary phase was at first investigated. Six commercially available barbiturates (Barbital, Phenobarbital, Amobarbital, Pentobarbital, Secobarbital and Thiopental) were well separated on an NAIP column by an isocratic elution with borate buffer (pH 7.0)-acetonitrile (9:1, v/v). Further, the applicability of the HPLC system including an NAIP column to the determination of barbiturates in human blood plasma was examined. Barbiturates extracted from plasma sample using a solvent extraction (hexane-diethyl ether, 3:7. v/v) were subjected to the HPLC system and determined by an internal standard method with UV detection at 220 nm. The recoveries of barbiturates spiked to human plasma were obtained in the range of 88.6 to 100.0%. The lower detection limits of barbiturates spiked ranged from 0.05 to 0.33 fig/mL, and the within-day and day-to-day precisions for plasma sample (n=5) gave relative standard deviations of less than 9 07% and 18.68%, respectively. Next, the applicability of an NAIP column to the separation of diastereomeric derivatives was studied. Epinephrine (EP), norephedrine (NE) and α-phenylethylamine (PA) carrying an aromatic ring were used as representative targets for derivatization with three kinds of chiral reagents. Resolution behavior on NAIP was compared with that on a conventional reverse phase ODS column. Diastereomeric derivatives of targets were satisfactorily separated by an NAIP column as well as an ODS column. The best separation of S(+)-1-(1-naphthyl)ethyl isocyanate derivatives with PA was obtained on an NAIP column and the calibration curves showed good linearity in the concentration range examined.