Target testing procedure for determining chemical kinetics from spectroscopic data with absorption shifts and baseline drift

Spectroscopic reaction monitoring can be used to collect data that contain information about a chemical reaction. The evaluation of kinetics from such data by the established nonlinear least squares (NLLS) technique assumes that all systematic variance in the data can be explained by the kinetic model. If effects are present in the data that cannot be explained by the model, such as baseline drift or absorption shifts, the estimated rate constant might be erroneous. An iterative target testing (TT) procedure is shown to yield good rate constant estimates when the spectroscopic data is influenced by additional sources of variance. Two examples of in situ infrared spectroscopic reaction monitoring of simple organic reactions are used to demonstrate the proposed methods greater tolerance to such effects.