Does the NMR measure the stream property directly, or is it a correlation?
NMR uses correlative methodologies similar to other spectroscopic measurements (i.e. NIR near infra-red spectroscopy), however, certain measurements can be made by measuring the stream properties directly. Typically, NMR analyzes the hydrogen nuclei in the sample to produce a spectrum of chemical information that describes the chemistry of the stream. In practice, Partial Least Squares regression algorithms are used for “chemometric” correlation of NMR spectra to chemical/physical properties of interest. Simply, the spectral data is used to develop models that predict the property based on a known set of laboratory data. Consequently, a wide range of analysis is recommended to ensure the predicted measurement for the on-line application is within the valid range of the model. However, outlying data is easily incorporated into the on-line model once a sample is captured and analyzed.
