E. Yamamoto et al., Methylcellulose-immobilized reversed-phase precolumn for direct analysis of drugs in plasma by HPLC, ANAL SCI, 17(10), 2001, pp. 1155-1159
We evaluated a new restricted access media (RAM) precolumn for direct analy
sis of drugs in plasma using a column switching HPLC system. The new RAM ma
terial was prepared by the modification of the external surface of porous s
ilica with hydrophilic methylcellulose (MC), followed by modification of th
e internal surface with octadecylsilane (ODS). The external surface of the
MC-immobilized ODS silica material (MC-ODS) suppressed the adsorption of pr
oteins, while the internal surface of MC-ODS retained various types of drug
s, such as ketoprofen, propranolol, caffeine and atenolol in plasma samples
. In addition, MC-ODS allowed direct analysis of drugs in a 1000- muL plasm
a sample to monitor trace amounts of analytes contained. Reduced efficiency
and clogging of the MC-ODS precolumn and/or the analytical column were not
observed even after the repetitive injection of plasma sample up to 40 mL.
Our results indicated that the MC-ODS precolumn could be used in pharmacod
ynamic and clinical studies.