O. Shirota et al., LOW CONCENTRATION DRUG ANALYSIS BY SEMI-MICROCOLUMN LIQUID-CHROMATOGRAPHY WITH A POLYMER-COATED MIXED-FUNCTION PRECOLUMN, The Journal of microcolumn separations, 7(1), 1995, pp. 29-35
The construction and performance of dual- and triple-column systems fo
r the analysis of dilute drug samples are described. The systems are b
ased on the following two separation processes: (1) deproteinization a
nd analyte fractionation using a short polymer-coated mixed-function (
PCMF) phase (10 mn x 4.0 mm i.d. column) and, (2) final separation usi
ng a C18 semi-microcolumn (1.5 to 2.0 mm i.d.). The surface structure
of the MF phase and the geometry of the packed column for the primary
separation made it possible to inject hundreds of microliters of serum
samples into the system. Analytes separated in the primary chromatogr
aphy are transferred to the main column with or without an intermediat
e column (35 mm x 1.0 mm i.d.). A system using an intermediate column
was designed to save time of analysis when a 1.5-mm i.d.(and smaller)
main column was used. The systems showed an increased concentration se
nsitivity for drug molecules, such as diazepam, carbamazepine, and phe
nobarbital, without any loss in chromatographic efficiency. Carbamazep
ine and phenobarbitalat 12.5 ppb and 50 ppb, respectively, in human se
rum were detected with good S/N ratio.