Journal article
Multivariate Calibration Models for Lysozyme from Near-Infrared Transmission Spectra in Scattering Solutions of Monodisperse Microspheres
Analytical chemistry (Washington), Vol.74(14), pp.3392-3399
07/15/2002
DOI: 10.1021/ac010976+
PMID: 12139045
Abstract
The ability to quantify lysozyme is demonstrated for a series of aqueous samples with different degrees of scattering. Near-infrared spectra are collected for two sets of lysozyme/scattering solutions. In both sets of samples, the solutions are composed of lysozyme dissolved in acetate buffer with suspended monodisperse latex microspheres of polystyrene. The diameter of the microspheres is 6.4 μm for the first set and 0.6 μm for the second. For each set, the amount of microspheres range from 0.005 to 0.998 wt %, the lysozyme concentrations range from 0.834 to 28.6 mg/mL, and solution compositions are designed to minimize correlations between the concentration of lysozyme and percentage of microspheres. Near-infrared spectra are collected individually for each set of solutions. Single-beam spectra are collected over the combination spectral range (5000-4000 cm-1, 2.0-2.5 μm) by transmitting the incident radiation through a 1.5-mm-thick sample that is maintained at 21 °C. Partial least-squares calibration models are evaluated individually for each data set both with and without wavelength optimization. Results indicate that models from raw, nonmodified, single-beam spectra are incapable of extracting lysozyme concentration from these highly scattering solutions. Accurate concentration measurements are possible, however, by implementing either a multiplicative scatter correction to the single-beam spectra or by taking the ratio of these single-beam spectra to an appropriate reference spectrum. In addition, digital Fourier filtering of these spectra enhances model performance. The best calibration model in the presence of 6.4-μm microspheres is obtained from multiplicative scatter corrected single-beam spectra over the 4550-4190-cm-1 spectral range. The mean percent error of prediction (MPEP) and standard error of prediction (SEP) for this model are 2.2% and 0.28 mg/mL, respectively. Likewise, the multiplicative scatter corrected spectra with wavelength optimization provided the best calibration model for the 0.6-μm data set. In this case, the MPEP and SEP are 2.3% and 0.44 mg/mL, respectively. In addition, the ability to predict lysozyme concentrations is evaluated for the situation where the degree of scattering is greater in the predication samples compared to the calibration samples. Differences in the prediction ability are,noted between the 6.4- and 0.6-μm data sets.
Details
- Title: Subtitle
- Multivariate Calibration Models for Lysozyme from Near-Infrared Transmission Spectra in Scattering Solutions of Monodisperse Microspheres
- Creators
- Carolyn E Green - Department of Chemistry, Department of Chemical and Biochemical Engineering, and Optical Science and TechnologyCenter, University of Iowa, Iowa City, Iowa 52242John M Wiencek - Department of Chemistry, Department of Chemical and Biochemical Engineering, and Optical Science and TechnologyCenter, University of Iowa, Iowa City, Iowa 52242Mark A Arnold - Department of Chemistry, Department of Chemical and Biochemical Engineering, and Optical Science and TechnologyCenter, University of Iowa, Iowa City, Iowa 52242
- Resource Type
- Journal article
- Publication Details
- Analytical chemistry (Washington), Vol.74(14), pp.3392-3399
- Publisher
- American Chemical Society
- DOI
- 10.1021/ac010976+
- PMID
- 12139045
- ISSN
- 0003-2700
- eISSN
- 1520-6882
- Language
- English
- Date published
- 07/15/2002
- Academic Unit
- Center for Biocatalysis and Bioprocessing; Fraternal Order of Eagles Diabetes Research Center; Chemistry
- Record Identifier
- 9984216591002771
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