DLS Solutions Applications : Spectroscopy

Spectroscopic-based detection systems involve some form of electro-magnetic radiation interacting with molecules and a detection scheme to measure properties of interest. For example, NIR and FTIR use transmission or reflectance to pass light through a sample, using wavelengths of incident light to give rise to some vibrational absorption allowing a direct measure of molecular functional groups. The detected spectrum is a measure of the %transmission at each wavelength, resulting in a system of fingerprinting or modeling for both qualitative and quantitative purposes. With Fluorescence instrumentation systems, an emission wavelength different than the excitation source is measured and relates to specific mechanisms in the sample matrix or leveraging some controlled probe-dye set to qualify or quantitate unknown samples. Chemiluminescence is similar to Fluorescence except that no excitation light is needed because the emission mechanism is based on internal chemistry. For example, in nature this can be seen in fire-flies. The basic concept in all of these methodologies is to devise a system that interacts with the sample, such that the instrument response can be calibrated out and the net signal used to analyze the data can be correlated to the sample. Near Infrared, a technique similar to FTIR, is used in process monitoring because it uses overtone bands and allows for longer sample pathlengths that support a robust sample interface. When more complicated mathematical models are needed to extract the desired data, the field of Chemometrics or Multivariate analysis is used. In simpler cases, straight-forward models are used to relate a small number of wavelengths with a linear model weighted to a property of interest. Classical and traditional laboratory methods paved the way for novel and modern applications. DLS Solutions has helped clients build systems to operate in many different settings.