Trace-level identity confirmation from infrared spectra by library searching and artificial neural networks

Confirmation of the identity of analytes at trace-level concentrations from infrared spectra is described. Both library search and artificial neural networks (ANNs) are used for this purpose. The effect of pre-processing, library composition and search algorithm on the results are investigated. Best separation of positives and negatives is obtained with ANN. Library search methods, however, are superior when prevention of false positives is essential. The correlation coefficient is scale-invariant and gives excellent results.