Calibration transfer employing univariate correction and robust regression.
This paper proposes a new method for calibration transfer, which was specifically designed to work with isolated variables, rather than the full spectrum or spectral windows. For this purpose, a univariate procedure is initially employed to correct the spectral measurements of the secondary instrument, given a set of transfer samples. A robust regression technique is then used to obtain a model with low sensitivity with respect to the univariate correction residuals. The proposed method is employed in two case studies involving near infrared spectrometric determination of specific mass, research octane number and naphthenes in gasoline, and moisture and oil in corn. In both cases, better calibration transfer results were obtained in comparison with piecewise direct standardization (PDS). The proposed method should be of a particular value for use with application-targeted instruments that monitor only a small set of spectral variables.
Instituto Tecnológico de Aeronáutica, Divisão de Engenharia Eletrônica, São José dos Campos, São Paulo 12228-900, Brazil.
Roberto Kawakami Harrop
RK
Galvão
Universidade Federal da Paraíba, CCEN, Departamento de Química, Caixa Postal 5093, João Pessoa, Paraíba CEP 58051-970, Brazil; Universidade Federal da Paraíba, CT, Departamento de Engenharia Química, João Pessoa, Paraíba CEP 58051-900, Brazil.
Sófacles Figueredo Carreiro
SF
Soares
Instituto Tecnológico de Aeronáutica, Divisão de Engenharia Eletrônica, São José dos Campos, São Paulo 12228-900, Brazil.
Marcelo Nascimento
MN
Martins
Universidade Federal de Pernambuco, Departamento de Engenharia Química, Recife, Pernambuco 50740-521, Brazil.
Maria Fernanda
MF
Pimentel
Universidade Federal da Paraíba, CCEN, Departamento de Química, Caixa Postal 5093, João Pessoa, Paraíba CEP 58051-970, Brazil. Electronic address: laqa@quimica.ufpb.br.
Mário César Ugulino
MC
Araújo
Calibration transfer; Multivariate calibration; Robust regression; Univariate correction; Variable selection