AUTOMATED MICROBORE LC WITH PEAK COMPRESSION FOR THE ASSAY OF GR138950 AND ITS ACTIVE METABOLITE IN HUMAN SERUM

Microbore LC with peak compression sample injection can facilitate imp roved methods in LC. The advantages of this approach were clearly illu strated in the automated, microbore LC-peak compression assay of GR138 950, a novel non-peptide angiotensin II antagonist selective for the A T(1) receptor and its active metabolite in human serum. An existing an alytical method had insufficient sensitivity to fully monitor the phar macokinetic profile of GR138950 and its active metabolite (GR205838) w hen low doses were administrated. Consequently a robust assay with a l ower limit of quantification was required. This was achieved by develo ping an alternative and fully automated solid phase extraction procedu re with on-line peak compression sample injection onto a microbore (2. 1 mm i.d.) column by means of a Zymate robot. This method produced cle aner extracts, improved precision, and lower limit of quantitation (1 ng mL(-1)) than had been achieved with the previous method which had u sed conventional LC.