Can XRF be useful when utilizing plastic bags? Field Portable X-Ray Fluorescence (FPXRF) instruments are used extensively in various stages of mining activity from grass roots exploration to exploitation, ore grade control, and even environmental investigations. FPXRF is a surface analysis technique that is capable of analyzing more than 30 elements in handheld XRF and 42 elements in a portable field x-ray lab in seconds in any type of sample, from soil to rock chips and drill cores. In some cases, depending on the sample type and required accuracy, clients may want to prepare their samples by grinding and pulverizing them, and then assaying them in a plastic bag. Depending on the thickness of bag and its composition, the number of x-rays reaching the detector will be lower than with direct assay. However, there are good correlations between lab assay data and portable XRF results. In such cases, calibration of the instrument using “cal-factors” is necessary. If an application does not need very low levels of detection, the analyzer can be calibrated to the sample through various media. A case study shows that for many applications, portable XRF analysis of samples through a plastic bag yields valuable and reliable data that can be used to make timely decisions in the field. The table above shows the recommended bag type based on concentration and composition of samples used in this study. The concentration column shows the maximum concentration in the samples used in this study. Limits of Detection (LOD) are shown for each bag type using Mining Mode. See the Effects of Paper and Plastic Bags on the Performance of Portable XRF Analyzers Application Note for more details, including methods, results, and spectra.