Total protein determinations by particle beam/hollow cathode optical emission spectroscopy (PB/HC-OES) system Part 2. Improved sensitivity through use of silica micro-particles as carrier agents for enhanced particle transport

Abstract

Silica micro-particles are investigated as possible carrier agents in total protein determinations by particle beam/hollow cathode optical emission spectroscopy (PB/HC-OES). Parametric optimization for sample treatment, including silica product type, silica concentration, sample incubation temperature and time, sonication time, and solvent pH, is performed for the analysis of bovine serum albumin (BSA) samples. A response curve of C I 193.0 nm emission was obtained under the optimized bovine serum albumin/silica interaction conditions. The analyte response curve exhibits clear improvements in terms of calibration curve slope and linearity in comparison with the case of simple aqueous solvent as the sample injection matrix. The logarithmic-scaled calibration curve allows a clearer view of the improvement of analyte response in the low-concentration (<5 ppm) portion of the calibration curve, which reflects the “carrier effect” of silica particles for PB-interfaced systems. Based on the linear regression statistics of the calibration curves, and the use of triplicate injection matrix blank injections, a limit of detection of 0.010 ppm BSA, 1.0 ng in absolute form, was obtained, with the addition of 5000 ppm of silica particles as the sample injection matrix. The value is ∼4-fold lower in concentration, and more than 6-fold lower in absolute mass, of BSA as compared to that obtained with 10% HCl as the injection matrix.