Total Protein Determinations by Particle Beam/Hollow Cathode Optical Emission Spectroscopy

Abstract

A novel method for quantitative total protein determinations is presented. Total protein content is determined by particle beam/hollow cathode optical emission spectroscopy (PB/HC-OES) through monitoring of carbon atomic emission. The PB/HC-OES offers such advantages as ease of operation, exclusion of labor-intensive sample pretreatment processes, rapid analysis, high sensitivity, and low detection limit. The method could also be adapted to be integrated to current microfluidics devices. Parametric optimization for sample introduction, nebulization, desolvation, and hollow cathode source conditions is performed for the analysis of aqueous bovine serum albumin solutions. Response curves of C (I) 193.0-nm emission were obtained under the optimized conditions with both 10% HCl and 100 micromL KCl added to the sample matrix as potential carriers. The detection limit for triplicate injections of bovine serum albumin standards was found to be on the single-nanogram level with 200-microL injections. The addition of KCl significantly improved the sensitivity, supporting the proposed "carrier effect" of chloride salts in the particle transport process. Results obtained here suggest a range of applications for the use of the PB/HC-OES source for total protein determinations; emphasis here is future use in assessing protein quantification in microfluidic systems.

Simultaneous multielement detection in particle beam/hollow cathode-optical emission spectroscopy

“…The HC glow discharge design was altered slightly from the one employed in previous works [10][11][12][13][15][16][17][18][19]21,22]. The HC was machined from a bulk copper rod with an inner diameter of 3.5 mm Fig.…”

“…At higher HC temperatures (>100°C), thermal volatilization is the major source of atomization. It has been previously shown that vaporization from the HC walls is the primary means of generating gas-phase species in the PB/HC-OES system [16,19]. Optimal HC temperatures have ranged from 200-300°C, with higher temperatures leading to pyrolysis of carbonaceous samples [10,11,16,19,20].…”

“…It has been previously shown that vaporization from the HC walls is the primary means of generating gas-phase species in the PB/HC-OES system [16,19]. Optimal HC temperatures have ranged from 200-300°C, with higher temperatures leading to pyrolysis of carbonaceous samples [10,11,16,19,20]. Given the difference in the placement of the heaters and thermocouples in the new design, it was imperative to characterize the role of "measured" temperature on the analyte responses.…”

“…Use of the PB allows work in an inert (discharge gas) atmosphere plasma, in the absence of solvent remnants, which makes it possible to detect "gaseous" elements and non-metals such as C, H, N, O, S, and P with high sensitivity. Previous experiments using monochromator detection system include determinations of metal salts and organometallic compounds, as well as the non-metal detection of proteins and amino acids based on C and H content [11][12][13][14][15][16][17][18]. Improvements have been made by substituting the monochromator with a polychromator, allowing for simultaneous, multielement detection, thus reducing data collection times, sample sizes, and the dependence on chromatographic retention times to substantiate elemental correlations.…”

Unconventional detection methods for microfluidic devices

“…Jin et al [97] introduced a particle beam/hollow cathode OED (PB/HC-OES) scheme for the analysis of total protein content by monitoring carbon atomic emission. After optimizing the analysis parameters, BSA solutions were determined with LOD reaching 15 ng/mL.…”