Analysis of Nanograms of Cadmium Using a Portable Total Reflection X-Ray Fluorescence Spectrometer

Nanograms of Cd are measured with a portable total reflection X-ray fluorescence spectrometer. A relationship between a detection limit for Cd and counting time is investigated. A Cd detection limit is improved with the increase in counting time, and a detection limit of 1 ng is achieved when a measurement is performed for 1800s. Cadmium quantitative performance is shown. Yttrium is used as an internal standard element, and the Cd K alpha/Y K alpha intensity ratio is linear with mass of Cd in the range from 10 to 1010 ng. Detection limits for Cd obtained with or without a 30 mu m thick Mo absorber are compared. The spectral background is reduced using the Mo absorber, leading to an increase in the signal to background ratio of the Cd K alpha line. However, the use of the Mo absorber results in a decrease in the net intensity of the Cd K alpha line. Therefore, a detection limit obtained with the Mo absorber is as low as that obtained without an absorber.