Rapid detection of phosphorus in water using silicon attenuated total reflectance infrared spectroscopy coupled with the algorithms of deconvolution and partial least squares regression

Abstract

Conventional methods for phosphorus (P) analysis are time-consuming and laborious, which limited the application of rapid P monitoring in water. In this study, silicon (Si) was applied to construct the systems of Fourier-transform mid-infrared attenuated total reflectance spectroscopy (FTIR-ATR) and was firstly applied in P determination in water using the typical P-O vibration with the wavenumber range of 1200–800 cm–1. FTIR-ATR spectra were obtained using Si crystal (Si-ATR) and conventional ZnSe crystal (ZnSe-ATR). The algorithms of deconvolution and partial least squares regression (PLSR) were involved to establish models for non-destructive and rapid measurement of P. The results showed that the typical absorption band of P was obtained from Si-ATR aligned with the conventional ZnSe-ATR. For the ZnSe-ATR, the coefficients of determination (R2) of PLSR models was more than 0.924, and the residual prediction deviation (RPD) was more than 3.02; while for the Si-ATR, the R2 was more than 0.883, and the RPD was more than 2.13. There was no significant difference between the predicted and real values, and there was no significant difference between Si and ZnSe crystal. The spectral pretreatment using deconvolution algorithm could effectively remove the interference of sulfate to reach an excellent prediction. It revealed that Si-ATR could be potential and alternative crystal for P detection. Furthermore, a novel P sensor was developed using Si-ATR, which achieved the rapid P monitoring in water with the advantage of accuracy, rapid, low price and durability.