Estimation of water interference for spectral correction

A method comprising:

• decomposing a training set corresponding to spectral data obtained for an interfering substance using an infrared spectrometry system to obtain a principal component matrix having a plurality of principal component vectors;
• generating a sample spectrum vector for a sample mixture using the infrared spectrometry system;
• variably rejecting portions of the sample spectrum vector that do not correspond to a selected one of the plurality of principal component vectors by incrementally:
• selecting a sub-region of the sample spectrum vector and a corresponding sub-region of the selected principal component vector;
• and
• multiplying the selected sub-region of the sample spectrum vector with the corresponding sub-region of the selected principal component vector to provide a coefficient indicative of the weighting of the selected principal component vector for the selected sub-regions;
• excluding sub-regions of the sample spectrum vector and corresponding principal component vector based on the incrementally provided coefficients;
• multiplying the sample spectrum vector with the principal component matrix for the non-excluded sub-regions to provide a weighting vector indicative of the contribution of the principal component matrix;
• multiplying the weighting vector by the principal component matrix to provide a predicted interference vector, the predicted interference vector corresponding to the interfering substance in the sample mixture, the interfering substance being capable of masking a presence or an absence of one or more chemicals of interest in the sample mixture;
• subtracting the predicted interference vector from the sample spectrum vector to provide a corrected spectrum vector;
• comparing the corrected spectrum vector to known spectrum data for one or more chemicals of interest to determine if the corrected spectrum vector is representative of a chemical of interest;
• and
• activating one or more visual or audible indicia when the corrected spectrum is representative of a chemical of interest.

A computer-readable storage medium comprising code, the code comprising:

• decomposing a training set corresponding to spectral data obtained for an interfering substance using an infrared spectrometry system to obtain a principal component matrix having a plurality of principal component vectors;
• receiving a sample spectrum vector for a sample mixture using the infrared spectrometry system;
• variably rejecting portions of the sample spectrum vector that do not correspond to a selected one of the plurality of principal component vectors by incrementally:
• selecting a sub-region of the sample spectrum vector and a corresponding sub-region of the selected principal component vector;
• and
• multiplying the selected sub-region of the sample spectrum vector with the corresponding sub-region of the selected principal component vector to provide a coefficient indicative of the weighting of the selected principal component vector for the selected sub-regions;
• excluding sub-regions of the sample spectrum vector and corresponding principal component vector based on the incrementally provided coefficients;
• multiplying the sample spectrum vector with the principal component matrix for the non-excluded sub-regions to provide a weighting vector indicative of the contribution of the principal component matrix;
• multiplying the weighting vector by the principal component matrix to provide a predicted interference vector, the predicted interference vector corresponding to the interfering substance in the sample mixture, the interfering substance being capable of masking a presence or an absence of one or more chemicals of interest in the sample mixture;
• subtracting the predicted interference vector from the sample spectrum vector to provide a corrected spectrum vector;
• and
• comparing the corrected spectrum vector to known spectrum data for one or more chemicals of interest to determine if the corrected spectrum vector is representative of a chemical of interest.