HPLC packed microbore columns with 3,5-dinitrobenzoyl derivative of trans-1,2-diaminocyclohexane as selector

Columns of small inner diameter have clear advantages over conventional columns, e.g., reduced consumption of mobile phase and of expensive stationary phases, high column efficiency, enhanced mass sensitivity on concentration-sensitive detectors and easy interfacing with mass spectrometers. Columns with inner diameters of 4.0, 2.0 and 1.2 mm were prepared using a chiral stationary phase containing the 3,5-dinitrobenzoyl derivative of (S,S)(+)- or R,R)(−)-1,2-diaminocyclohexane covalently bonded to the siliceous matrix. Two classes of racemic compounds of pharmaceutical interest were chosen to investigate the performance of chiral microcolumns: α-methylarylacetic acid anti-inflammatory agents (as 1-naphthalenemethylamides) and amino alcohol β-blocking agents (as oxazolidin-2-ones). These compounds were easily resolved (α = 1.21, 1.41 and 1.49 for ibuprofen, flurbiprofen and naproxen, respectively, and 1.40 for propanolol and pindolol) with very short analysis times. Hydrogen bonding, π-π interactions and steric hindrance are involved in the chromatographic resolution process.