Applications

Unknown Samples Identification

Each substance has its own unique Raman scattering spectrum that can be used to identify it. This can be achieved by comparing substance’s Raman spectrum against a spectrum from a spectra libraries. There are several hundred thousands of inorganic compounds and tens of millions of organic compounds. In order to make an effective search in spectra libraries, it is recommended to choose respective libraries only (e.g. pharmaceuticals or polymers, petrochemical products or minerals). The software then matches a spectrum from an undefined sample against known spectra in a library. Hence, identifying the most likely candidate.

Below are some of the most common use cases.

Comparison of the spectrum of aspirin sample with a library one

Express Screening of Known Samples

Express screening is used for quality control purposes in industrial production (e.g. quick identification of a large number of identical samples). In that case, a screening sample’s spectrum compared against user-defined reference spectra.
Coda Devices’ software enables end-user to create custom reference spectra libraries out-of-the-box.

Creating a user spectral library

Mixture Analysis

The identification of mixtures’ components is a more complex task. Coda Devices’ software can quickly identify components as well as their relative percentage values in a mixture. For a successful mixture analysis components’ spectra should significantly differ from each other and component should contribute no less than 10% to overall mixture’s volume. Up to four components and their percentage values can be determined if these conditions are met.

A longer measurement time is required for components with lower concentrations. For example, 10 times longer time is needed for identifying a component that contributes only 3% to mixture’s volume.

Separation of components with overlapped spectral lines is possible with the use of extra spectral data processing software.

Identification of four components in a mixture with measurement time of 15 seconds

Raman spectroscopy can be used for quantitative analysis. The intensity of spectral lines is proportional to the concentration of respective substances in a sample. Quantitative analysis is used as product quality control to ensure target substance concentration is within the specified range.

Quantitative analysis requires initial calibration. This calibration implies measurement of samples with predefined concentrations of analytes. The values of the calibration samples must be distributed evenly over the possible measurement range of concentrations, as well as the range of their values must be wider than the intended concentrations of the measured sample values.