A capillary zone electrophoresis study of the effect of precursors and ultrasonic treatment on the morphology of hydroxyapatite particles

Abstract

A set of analytical techniques is proposed for studying samples of calcium hydroxyapatite (HA) synthesized on the basis of calcium nitrate or calcium hydroxide as precursors. A comparative study of parti cle size distribution in HA samples is performed using capillary zone electrophoresis (CZE), scanning elec tron microscopy (SEM), dynamic light scattering (DS), and static light scattering (SS). The effect of heat treatment on the morphology of the synthesized products is evaluated. It is found that the effect of ultrasound (US) on the dispersity of HA particles in aqueous suspensions depends on the nature of the precursor and heat treatment. It is shown that the HA particles synthesized from calcium hydroxide (HA-OH) aggregate more rapidly than the particles synthesized from calcium nitrate (HA-NO 3 ). After the ultrasonic treatment of sus pensions, the relative concentration of large HA-NO 3 submicroparticles increased, while particle size distri bution in the suspension of HA-OH remained virtually the same. The heat treatment of HA powders at 900°C reduced the ability of particles to aggregate. It is found by CZE that, with increasing time of ultrason ication of suspensions, the relative concentration of nanoscaled and similar in size HA-NO 3 submicroparti cles increased markedly, while it changed only slightly in the HA-OH suspension. The reasons for the differ ences are discussed. A procedure for determining the concentration of HA submicroparticles in suspension by CZE is proposed. A linear dependence of normalized peak areas on HA concentration in suspension is obtained.