X-Ray Fluorescence Analysis Applied to Small Samples

Abstract

We describe an adaptation of photon excited x-ray fluorescence analysis which is optimized for the analysis of small samples. A fine focus x-ray tube is used in conjunction with small diameter detector collimators in order to focus on a small sample volume with as high sensitivity as possible. Sample areas of less than 1 mm diameter can be analyzed with ppm detectability. In applications involving the analysis of human hair samples, a minimum detectable limit of 10 ppm Hg can be realized in a 1 mm long segment of a single hair in a counting time of 200 seconds. Simultaneous measurements of the sample mass can be obtained from the intensity of the incoherent scattering. An automated x-ray fluorescence analysis system using the technique for the scanning of elemental profiles in such hair samples will be described.

The transistor and energy‐dispersive x‐ray spectrometry: roots and milestones in x‐ray analysis

“…The first exploitation of this technique in EDXRF was made by Jaklevic in 1977, when he used a beam with fwhm of 1.25 mm to analyze human hair. 40 Small apertures defined the beams. The total mass of the specimen was determined by incoherent scatter while simultaneously measuring trace elements.…”

Nondestructive x-ray fluorescence spectrometry for determination of trace elements along a single strand of hair

“…In 1977 a prototype X-ray fluorescence instrument was built to do longitudinal analyses on a single strand of human hair (4). The goal in the present research was to develop a computer-automated analytical instrument with associated computer software and operating techniques such that elemental 0003-2700/82/0354-1844$01.25/0 concentrations could be easily and routinely scanned along a single strand.…”

X-ray spectrometry

“…Using a texture goniometer to allow an X-ray line focus to be moved systematically in steps across the sample and then applying mathematical deconvolution to the measured intensities, it is claimed that a resolution of 100 µ can be achieved. A somewhat simpler method for analysis of small samples with a resolution of approximately 1 mm2 is that of Jaklevic and French (60). They use a small 100-watt X-ray tube to irradiate the sample which in turn is close to a 1-mm diameter aperture in front of a Si(Li) detector.…”