The current work of the European X-ray Spectrometry Association’s X-Ray Fundamental Parameters Initiative focuses mainly on the accuracy of XRF, with considerable attention to mass attenuation coefficients (MACs). The issue of the accuracy achievable by PIXE also needs attention to detectors, database and methodology if use of our method is to grow. This needs specific carefully designed experiments, not endless repeats of what was already done. For example, recent experiments at Guelph led us to change the GUPIX MAC database from XCOM to FAST for low energy K X-rays in low-Z absorbers. This step eliminated systematic errors for Na – Si in silicate rock analysis. Together with correcting for non-linearity it enabled agreement on average better than 1% for elements Na – Fe in silicate rocks and glasses. This accuracy level is necessary if potential PIXE users are to have confidence in our outcomes.