title: A genetic algorithm-based framework for wavelength selection on sample categorization.
abstract: In forensic and pharmaceutical scenarios, the application of chemometrics and optimization techniques has unveiled common and peculiar features of seized medicine and drug samples, helping investigative forces to track illegal operations. This paper proposes a novel framework aimed at identifying relevant subsets of attenuated total reflectance Fourier transform infrared (ATR-FTIR) wavelengths for classifying samples into two classes, for example authentic or forged categories in case of medicines, or salt or base form in cocaine analysis. In the first step of the framework, the ATR-FTIR spectra were partitioned into equidistant intervals and the k-nearest neighbour (KNN) classification technique was applied to each interval to insert samples into proper classes. In the next step, selected intervals were refined through the genetic algorithm (GA) by identifying a limited number of wavelengths from the intervals previously selected aimed at maximizing classification accuracy. When applied to Cialis®, Viagra®, and cocaine ATR-FTIR datasets, the proposed method substantially decreased the number of wavelengths needed to categorize, and increased the classification accuracy. From a practical perspective, the proposed method provides investigative forces with valuable information towards monitoring illegal production of drugs and medicines. In addition, focusing on a reduced subset of wavelengths allows the development of portable devices capable of testing the authenticity of samples during police checking events, avoiding the need for later laboratorial analyses and reducing equipment expenses. Theoretically, the proposed GA-based approach yields more refined solutions than the current methods relying on interval approaches, which tend to insert irrelevant wavelengths in the retained intervals. Copyright © 2016 John Wiley & Sons, Ltd.
authors.affiliation: Department of Industrial Engineering, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil.
authors.forename: Michel J
authors.initials: MJ
authors.lastname: Anzanello
authors.affiliation: Department of Industrial Engineering, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil.
authors.forename: Gabrielli
authors.initials: G
authors.lastname: Yamashita
authors.affiliation: Chemistry Institut, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil.
authors.forename: Marcelo
authors.initials: M
authors.lastname: Marcelo
authors.affiliation: Department of Industrial Engineering, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil.
authors.forename: Flávio S
authors.initials: FS
authors.lastname: Fogliatto
authors.affiliation: Rio Grande do Sul Technical and Scientifical Division, Brazilian Federal Police, Porto Alegre, RS, Brazil.
authors.forename: Rafael S
authors.initials: RS
authors.lastname: Ortiz
authors.affiliation: Department of Pharmacy, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil.
authors.forename: Kristiane
authors.initials: K
authors.lastname: Mariotti
authors.affiliation: Chemistry Institut, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil.
authors.forename: Marco F
authors.initials: MF
authors.lastname: Ferrão
mesh_terms: D000465:Algorithms; D000779:Anesthetics, Local / Q000737:chemistry* / Q000145:classification; D003042:Cocaine / Q000737:chemistry* / Q000145:classification; D058110:Counterfeit Drugs / Q000737:chemistry* / Q000145:classification; D013287:Illicit Drugs / Q000737:chemistry / Q000145:classification; D000068677:Sildenafil Citrate / Q000737:chemistry* / Q000145:classification; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods*; D000068581:Tadalafil / Q000737:chemistry* / Q000145:classification; D014665:Vasodilator Agents / Q000737:chemistry* / Q000145:classification
chemical_list: D000779:Anesthetics, Local; D058110:Counterfeit Drugs; D013287:Illicit Drugs; D014665:Vasodilator Agents; D000068581:Tadalafil; D000068677:Sildenafil Citrate; D003042:Cocaine
keywords: ATR-FTIR; counterfeiting; genetic algorithm; wavelength identification