Synthesis of silica-based benzeneboronic acid affinity materials and application as pre-column in coupled-column high-performance liquid chromatography

Three silica-based benzeneboronic acid affinity materials were synthesized by using an m-aminobenzeneboronic acid as the ligand and using three different spacer arms. Under high-pressure, three affinity pre-columns were packed with these materials and the retention of every affinity pre-column with 11 urinary nucleosides was studied. With different spacer arms of boronic acid-substituted silica materials, the absorption to vicinal alcohols (cis-diols) and stability under acidic elution conditions are of great difference. Coupled-column liquid chromatographic methods for the direct analysis of urinary nucleosides were respectively established. As a result, two of three affinity pre-columns showed good chromatographic property in the on-line analysis of urinary nucleosides. The coupled-column system including pre-column I is the best with excellent linearity (R2 > 0.995), good recoveries (85.6–96.9%) and reproducibility (R.S.D.: 1.01–4.02%). The pre-column I could at least endure 150 repetitive injections of a 100 μL urinary sample.