Improvement of a TXRF setup to obtain detection limit in the low ppb range

Abstract

To achieve the low ppb detection level a major experimental effort and optimization of the TXRF setup are required. The new solution described in this paper leads to enhancement of the TXRF intensity and to improved signal/noise ratio. The adjusted quartz reflector allows control of a reflection angle of a photon beam with respect to the crystal surface with high precision up to 0.006°. The installed adjusted diaphragm (followed by the quartz reflector) substantially reduces the level of registered background in the studied range of x-ray energy. The dependence of the x-ray spectra shape, x-ray intensity and detection limit on the diaphragm width and its position on the photon beam as well as on the value of the glancing angle of x-rays from the sample carrier have been studied. The new optimal parameters found result in essential improvement in detection limit equal to ∼1.0 ppb for elements detected in a liquid sample without any special pre-concentration preparation. Also a very good repeatability of measurements has been reached. Copyright © 2006 John Wiley & Sons, Ltd.