title: Multicriteria wavenumber selection in cocaine classification.
abstract: Cocaine ATR-FTIR spectra consist of a large number of wavenumbers that typically decreases the performance of exploratory and predictive multivariate techniques. This paper proposes a framework for selecting the most relevant wavenumbers to classify cocaine samples into two categories regarding chemical composition, i.e. salt and base. The proposed framework builds a wavenumber importance index based on the Bhattacharyya distance (BD) followed by a procedure that removes wavenumbers from the spectra according to the order suggested by the BD index. The recommended wavenumber subset is chosen based on multiple criteria assessing classification performance, which are recalculated after each wavenumber is eliminated. The method was applied to ATR-FTIR spectra from 513 samples of cocaine, remarkably reducing the percent of retained wavenumbers and yielding near to perfect classifications in the testing set. In addition, we compared our propositions with other methods tailored to wavenumber selection; we found that the proposed framework, which relies on simple mathematical fundamentals, yielded competitive results.
authors: Department of Industrial Engineering, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil. Electronic address: michel.anzanello@gmail.com.
authors: M J
authors: MJ
authors: Anzanello
authors: Department of Industrial Engineering, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil.
authors: A
authors: A
authors: Kahmann
authors: Institute of Chemistry, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil.
authors: M C A
authors: MC
authors: Marcelo
authors: Department of Pharmacy, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil.
authors: K C
authors: KC
authors: Mariotti
authors: Institute of Chemistry, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil.
authors: M F
authors: MF
authors: Ferrão
authors: Rio Grande do Sul Technical and Scientific Division, Brazilian Federal Police, Porto Alegre, RS, Brazil.
authors: R S
authors: RS
authors: Ortiz
mesh_terms: D000697:Central Nervous System Stimulants / Q000032:analysis* / Q000145:classification*; D003042:Cocaine / Q000032:analysis* / Q000145:classification*; D016002:Discriminant Analysis; D016018:Least-Squares Analysis; D008956:Models, Chemical; D015999:Multivariate Analysis; D025341:Principal Component Analysis; D017550:Spectroscopy, Fourier Transform Infrared; D013678:Technology, Pharmaceutical / Q000379:methods*
chemical_list: D000697:Central Nervous System Stimulants; D003042:Cocaine
keywords: Cocaine; KNN; LDA; PNN; Wavenumber selection