Biological sample preparation by using restricted-access nanoparticles prepared from bovine serum albumin: application to liquid chromatographic determination of β-blockers

Restricted-access nanoparticles (RANPs) were prepared from bovine serum albumin by coacervation. They have an average sized of 311 nm. They were characterized and used to capture the beta-blockers atenolol, metoprolol and propranolol from untreated biological samples. It is shown that both high protein affinity drugs (propranolol) and low protein affinity drugs (atenolol) could be rapidly extracted from plasma. This is revealed by kinetic and isothermal adsorption studies. On the other hand, almost all proteins from the sample were excluded. This demonstrates the efficiency of RANPs as restricted-access material. Sample preparation was carried out by solid phase microextraction using a probe obtained by the fixation of the RANPs at the end of a glass capillary. Atenolol (in concentrations from 100 to 1200 mu g L-1), metoprolol (from 80 to 1000 mu g L-1) and propranolol (from 15 to 200 mu g L-1) were extracted from spiked plasma samples and analyzed by LC MS/MS without using a separation column. Correlation coefficients >0.99, good precision, accuracy, robustness, and lack of memory effects were observed for all of the analytes. The detection limits (at an S/N of 3) are 25.6, 14.6, and 3.8 mu g L-1 for atenolol, metoprolol and propranolol, respectively. Ten samples can be simultaneously extracted within similar to 15 min. Plasma samples of patients undergoing medical treatment were successfully analyzed with the method.