Low concentration drug analysis by semi‐microcolumn liquid chromatography with a polymer‐coated mixed‐function precolumn

Abstract

Abstract. The construction and performance of dual-and triple-column systems for the analysis of dilute drug samples are described. The systems are based on the following two separation processes: (1) deproteinization and analyte fractionation using a short polymer-coated mixed-function (PCMF) phase (10 mm x 4.0 mm i.d. column) and, (2) final separation using 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 chromatography are transferred to the main column with or without an intermediate column (35 mm x 1 .O 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 sensitivity for drug molecules, such as diazepam, carbamazepine, and phenobarbital, without any loss in chromatographic efficiency. Carbamazepine and phenobarbital at 12.5 ppb and 50 ppb, respectively, in human serum were detected with good S/N ratio.

Direct analysis of clomipramine in human plasma by microbore high performance liquid chromatography with column-switching

“…Capcell Pak MF Ph-1 was an appropriate precolumn for the deproteinization and clomipramine fractionation in column-switching for microbore LC. Since MF Ph-1 phase consists of hydrophilic polyoxyethylene groups and hydrophobic phenyl groups on a silica surface [19], large molecules such as plasma proteins pass through the column quickly and clomipramine is retained longer by interacting with bonded hydrophobic groups. To choose washing solvent and the appropriate time for columnswitching, the retention behavior of clomipramine on an MF Ph-1 column was examined using different mobile phases.…”

“…Column-switching is a technique that directly analyses biological samples at 100/zL levels for microbore LC [16][17][18][19] as well as conventional LC [11,12,20,21]. Column-switching system based on microbore LC for clomipramine can provide higher sensitivity, shorter analysis time and easier sample treatment than other previously reported, column-switching methods for conventional LC [11,12].…”

Determination of myristicin in rat serum samples using microbore high performance liquid chromatography with column-switching

“…In this study, microbore LC was chosen for the quantitation of myristicin in serum samples because of advantages such as increased detectability and lower solvent consumption. Column-switching systems have been used for conventional LC [22][23][24][25][26] and microbore LC [27][28][29] for the online trace enrichment of analytes, which is appropriate for the isolation of myristicin from serum samples because of its volatility and low concentration.…”

Application of semi-microcolumn liquid chromatography to forensic analysis

“…1). Benefits of semi-microcolumn LC seemed most pronouncing when a columnswitching system was arranged [6] (Fig. 2).…”