New Sapphire Discs S2 PICOFOX Sapphire Sample Carriers Sensitive Detection of Silicon The most common sample carriers for Total Reflection X-ray Fluorescence (TXRF) analysis are quartz discs (order no. B-A20V09). However, due to the silicon (Si) peak caused by this carrier material the detection of Si is almost impossible. On the other hand, Si-free disc materials like polyacrylics show a significant scattering background which leads to unsatisfactory detection limits for certain applications. LLD and background counts for Si using different carrier materials Now, sample carriers made of sapphire are available at Bruker Nano (order no. B-A20V21). In combination with TXRF these sample discs enable a fast, straightforward method for sub-ppm detection of Si. In the following, different carrier materials are compared and the application of the highly polished sapphire discs for water and pharmaceutical samples is briefly described. Fig. 1: Comparison of LLD (dark blue) and background counts (light blue) for Si measurements using different types of sample discs for TXRF. Comparison of different sample carrier materials for TXRF TXRF spectra of a Si washout solution An aqueous solution containing an internal standard of 1 mg/L gallium (Ga) was spiked with 100 mg/L Si. 10 µl of this solution was prepared on four different types of carriers: quartz glass, acrylic glass, sapphire and glassy carbon. In each case the sample was measured with the TXRF spectrometer S2 PICOFOX for 1000 s at 50 kV, 600 µA. Figure 1 shows the background intensities and the lower limit of detection (LLD) for each carrier type. It clearly demonstrates the strong correlation between background and LLD, whereas the sapphire disc provides with about 102 µg/L the best LLD for Si. It is about four times lower compared to an acrylic glass disc. Detection of Si washout during pharmaceutical production Peristaltic pumps with Si tubes are commonly used in pharmaceutical production processes, whereby the washout of Si is a critical parameter to be controlled regularly. In an experiment the internal standard scandium (Sc, 10 mg/L) was added to a typical washout solution and was measured with the S2 PICOFOX at 50 kV, 600 µA. Figure 2 shows the spectrum of the washout solution with a clearly visible Si peak. The Si concentration was calculated to be 670 µg/L and the LLD to be 120 µg/L. Fig. 2: Spectra of a Si tube washout measurement after preparation on a sapphire sample disc. Sapphire sample carriers, polished discs Dimensions Diameter: 30 mm, height: 3 mm Order no. B-A20V21 Scope of delivery Set of 25 pieces Cleaning RBS 50 / 10 % HNO3 (same cleaning as for quartz discs) Lifetime No limitation Note Due to small impurities in naturally grown sapphire, these discs are not suitable for detecting specific elements at low µg/kg levels More information required ? Please contact us or find your local partner at www.bruker.com Bruker Nano GmbH Bruker AXS GmbH Bruker AXS Inc. Berlin · Germany Phone +49 (30) 670990-0 Fax +49 (30) 670990-30 [email protected] Karlsruhe · Germany Phone +49 (7 21) 50997-0 Fax +49 (7 21) 50997-5654 [email protected] Madison, WI · USA Phone +1 (608) 276-3000 Fax +1 (608) 276-3006 [email protected] www.bruker.com © 2013 Bruker Nano GmbH. Printed in Germany. Description All configurations and specifications are subject to change without notice. Order No. DOC-S81-EXS003. Technical Specifications