Improvement of total reflection X-ray fluorescence spectrometer sensitivity by flowing nitrogen gas

Abstract

The intensity of Ar Kα line was reduced by a factor of 17 times by flowing more than 400mLmin−1 of N2 gas through gas pipe placed at the gap between the X-ray detector and the sample stage of the total reflection X-ray fluorescence (TXRF) spectrometer. The signal-to-background ratios of characteristic X-rays with energies less than 8keV were improved by flowing N2 gas owing to the reduction of peak pileups related to the Ar Kα peak. The improvement of the signal-to-background ratios became significant as the energies of the characteristic X-rays approached that of the Ar Kα line (2.96keV) for characteristic X-rays with energies less than 5keV. When 1μL of solution containing 10mgL−1 cadmium (10ng) was measured with the TXRF spectrometer by flowing N2 gas, Cd Lα line was clearly observed, although the Cd Lα line overlapped with the Ar K lines without flowing N2 gas. The lower limit of detection of cadmium evaluated from the Cd Lα line was improved from 7.0 to 2.2ng by flowing N2 gas. This N2 gas flowing technique can be applied to trace element analysis of cadmium in solutions which do not contain potassium such as leaching solutions from products containing cadmium in TXRF and conventional XRF measurements.