Total Reflection X-ray Fluorescence Spectrometric Analysis of Ten Lanthanides at the Ultratrace Level Having a High Degree of Overlap in the Emission Lines.

ABSTRACT

The extensive use of lanthanide elements in the medical, electrical, agricultural, and nuclear fields has increased their contamination in the environment. The detrimental effect of lanthanides on human health can be reduced or eliminated by their fast determination in the concerned specimen. For this purpose, an offline conjugation of the cloud point extraction (CPE) process with total reflection X-ray fluorescence (TXRF) spectrometry was done. This process was found to provide simple, quick, and precise simultaneous determination of ten lanthanides whose emission lines have a high degree of overlap at the ultratrace level. N,N,N',N'-tetra-octyl-diglycolamide in triton X-114 micelles was found to offer a selective CPE of all of the lanthanides in the presence of higher concentrations of naturally abundant cations and anions. A multivariative partial least-squares regression (PLSR) calibration approach was preferred due to the complex overlapped spectra of L lines of the lanthanides. Ten lanthanides, viz., La, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Tm, and Lu, were simultaneously determined by this method, having concentrations in the range from 10 to 5 × 103 µg L-1. The proposed method was validated by analyzing three certified reference materials (CRMs), viz., NASS-7 seawater, SRLS-6 river water, and NIST 1640a natural water, via standard addition with the relative standard deviations of ≤10%.