Optimization of geometry for x‐ray analysis of rare earth materials

Abstract

A method of sample excitation is proposed for obtaining good sensitivity and detection limits for rare earth elements (57 ≤ Z ≤ 69) by energy‐dispersive X‐ray fluorescence analysis using a 241Am radioisotope source. Detection limits of about 100—300 ng for most of the elements using a thin multi‐element sample on a Mylar backing are obtained for a counting time of 1 h with a 100 mCi source. The configuration employed is a close‐coupled collimated side source geometry in which the sample is mounted at 45° to the plane of the detector. This geometry was found to be superior to the commonly used wide annular geometry in terms of the detection limits obtained for the analysis of rare earth elements. A comparative study of the performance of different source geometries using both Mylar‐ and cellulose‐based samples is described.

High-performance liquid chromatographic determination of the magnetic resonance imaging contrast agent Gadocoletate ion in human plasma, urine and faeces

“…Code B22956/1) is a derivative of gadopentetate bearing on the methylene group of the centrally located acetate group in S-configuration, a propionic acid linker to the amino group of the 3␤-amino-analogue of deoxycholic acid [1]. Its chemical name according to radiotracer techniques [3] or by spectrometric techniques such as atomic absorption spectrometry [4], inductively coupled plasma atomic emission spectrometry [5] and X-ray fluorescence [6]. However, these techniques are unable to distinguish the contrast agent and the various chemical species of gadolinium potentially present in the sample (parent compounds and metabolites).…”

Speciation of gadolinium based MRI contrast agents in environmental water samples using hydrophilic interaction chromatography hyphenated with inductively coupled plasma mass spectrometry

“…Concentrations of gadolinium can be determined by using spectrometric techniques such as atomic absorption spectrometry, 23 inductively coupled plasma atomic emission spectrometry, 24 inductively coupled plasma mass spectrometry 25 and X-ray fluorescence. 26 However, these techniques are unable to distinguish the contrast agent and the various chemical species of gadolinium potentially present in the sample. To gather more detailed information about the Gd species, chromatographic techniques are required to separate the particular gadolinium compounds and to detect them individually.…”