Moving window partial least squares after orthogonal signal correction as a coupling method for determination of uranium and thorium by ultrasound‐assisted emulsification microextraction

Abstract

This study, a fast, simple, and efficient ultrasound-assisted emulsification microextraction coupled with orthogonal signal correction-moving window partial least squares (OSC-MWPLS) was successfully used to preconcentration and simultaneous spectrophotometric determination of uranium and thorium in water samples. Response surface methodology based on a Box-Behnken design was used to optimize the extraction conditions. The analysis of variance and some statistical tests such as lack-of-fit and coefficient of determination (R 2 ) showed good fit of the experimental data with the second-order polynomial model. Under the optimum conditions, the calibration graphs were linear in the range of 10.0 to 230.0 and 10.0 to 250.0 ng mL −1 with detection limits of 3.11 and 3.56 ng mL −1 (3S b /m) for uranium and thorium, respectively. The preconcentration factor of this method for uranium and thorium reached 192. Repeatability (intra-day) and reproducibility (inter-day) were obtained 1.23% and 2.18% for uranium and 1.34% and 1.95% for thorium, respectively. The OSC was used for preprocessing of data matrices, and also MWPLS regression has been proposed for the selection of informative spectral intervals. In this paper, ultrasound-assisted emulsification microextraction coupled with OSC-MWPLS method was presented for the first time. The root mean square error of prediction for uranium and thorium with PLS, OSC-PLS, and OSC-MWPLS were 11.755, 10.335 and 5.301, 5.399 and 0.974, 0.986 ng mL −1 , respectively. The results indicated that practical and environmentally friendly proposed method could be successfully used to the simultaneous determination of uranium and thorium in different environmental water samples.

Sonochemistry of actinides: from ions to nanoparticles and beyond

“…The effect of ultrasound was attributed to the efficient nucleation due to the cavitation microbubbles and intensive acoustic microstreaming as well [103]. Khorshidi et al applied 40 kHz ultrasound during the sample preparation step before spectrophotometric measurements were applied for the simultaneous determination of the concentrations of thorium and uranium in aqueous solutions [104]. The ultrasound-assisted emulsification micro-extraction approach consist in the rapid injection of small amounts of extracting solvents (carbon tetrachloride) in a sonicated aqueous media containing the elements of interest.…”

“…The as-formed cloudy solution is then centrifuged to concentrate the solvent before micrometric volumes are taken with a syringe prior to analyses. The authors reported several advantages including an acceleration of the formation of fine cloudy solutions with a minimum consumption of organic solvent, a reduced extraction time and a better extraction efficiency [104].…”

A novel wavelength selection strategy for chlorophyll prediction by MWPLS and GA

“…Kennard-Stone (KS) was the most commonly employed sample set partitioning method. The Euclidean distance was used in the method as the reference condition for selection, whose calculation formula is as Equation (8). As can be seen, KS selects samples only based on spectral features without considering the influence of property variables [16] .…”

“…MWPLS builds a series of partial least squares (PLS) models in a window that moves over the whole spectral region and then locates useful spectral intervals in terms of the least complexity of PLS models reaching a desired error level. The main advantage of MWPLS is that the model is very stable against the interference from non-composition related factors [8] . However, in the process of such interval selection methods, some noises may be retained while some really useful information may be dropped, since they are always mixed together [9] .…”