Development of new calibration procedures in Micro X-Ray Fluorescence (MXRF) using Thermal Inkjet Picofluidic System (TIPS) delivering droplets of picoliter volume, and their application for the characterization of aerosol particulate matter

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Total Reflection X-Ray Fluorescence (TXRF) is a powerful method for determination of traces and ultra traces of elements where sample material is limited. One major drawback of the method is that the analysis is especially sensitive for the sample morphology. This hampers the direct analysis of samples with a complex matrix (e.g. urine, blood). Commonly microliter volumes are used to deposit liquid sample material. As the control on the drying process is limited these specimens often suffer from inhomogeneous distribution of standard and analyte and easily exceed the critical thickness required for a precise analysis with TXRF (ca. 4 μm).Therefore in this study we evaluate specimen preparation of samples having a complex matrix (e.g. As in urine in a cooperation with the National Institute of Standards and Technology Gaithersburg, MD) using a prototype Thermal Inkjet Picofluidic System (TIPS) delivering picoliter volumes (1-200 pL) for direct TXRF analysis. The TIPS is exclusively available at the Los Alamos National Laboratory and has been introduced for the preparation of references in Micro X-Ray Fluorescence (MXRF) in the first part of this research stay.Essential parameters like sample morphology and chemical homogeneity, will be studied using Atomic Force Microscopy (AFM) and MXRF (focal spot 10 μm). Since the new sample preparation procedure proved its value, the TIPS will be integrated into a prototype grazing-incidence monochromatic micro XRF (GI-MMXRF) instrument. This prototype will then be evaluated for rapid and reliable analysis of various samples.