Direct detection of phoxim in water by two-dimensional correlation near-infrared spectroscopy combined with partial least squares discriminant analysis

This paper has established a simple method to detect directly phoxim in water. In the light of two-dimensional correlation analysis, the band of wavenumber for near-infrared spectroscopy of the model is between 5364.8 and 7552.9 cm−1, the rate of accuracy for partial least squares discriminant analysis to calibration set (n = 149) is 100%, prediction set (n = 75) is 93.3% and the overall rate of accuracy for all the samples is 97.8% under the limit of detection 1 μg ml−1 owing to the spectra preprocessing by standard normal variate transformation and multiplicative scatter correction. It is made clear that this method (two-dimensional correlation analysis combined with partial least squares discriminant analysis) is effective to detect directly phoxim in water.

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► Partial least squares discriminant analysis was investigated.
► Two-dimensional correlation analysis could obviate irrelevant variables.
► Provide a speedy, low-cost and easy-to-use method to determine phoxim in water.
► Encourage for applying the method in identifying other pesticide residue.