A novel calibration strategy based on background correction for quantitative circular dichroism spectroscopy.

Area of Science:

• Analytical Chemistry
• Spectroscopy
• Biochemistry

Background:

• Quantitative analysis using circular dichroism (CD) spectroscopy is hindered by light-absorbing interferences in real-world samples.
• Matrix differences between real-world and standard samples cause systematic errors in CD spectroscopy quantification.
• Existing calibration models struggle with complex sample matrices, limiting accurate analyte determination.

Purpose of the Study:

• To propose a novel calibration strategy for quantitative CD spectroscopic analysis that mitigates matrix effects.
• To enable accurate quantification of analytes in complex samples using CD spectroscopy.
• To compare the performance of the new strategy against conventional methods.

Main Methods:

• Developed a calibration strategy involving projecting CD spectra onto an orthogonal space to background absorbers.
• Built a multivariate calibration model on transformed CD spectra of standard samples.
• Applied the strategy to quantify Pb²⁺ in cosmetic samples using CD spectroscopy and a G-quadruplex DNAzyme (PS2.M).

Main Results:

• The proposed strategy effectively reduced the influence of matrix differences between standard and cosmetic samples.
• Accurate and precise quantification of Pb²⁺ was achieved, comparable to atomic absorption spectroscopy.
• The method demonstrated simplicity and effectiveness for analyzing analytes in complex matrices.

Conclusions:

• The novel calibration strategy enhances the accuracy and precision of CD spectroscopy for quantitative analysis in complex samples.
• This approach overcomes limitations posed by background absorbers and matrix effects.
• The strategy offers a simple and effective solution for reliable analyte quantification using CD spectroscopy.