Although portable X-Ray Fluorescence (XRF) technology has gained widespread acceptance in the environmental community as a viable analytical approach for field screening test, it needs to be evaluated with sufficient data and meet its performance characteristics to be employable for decision making purposes. Usually, for an XRF sample, the most interesting query is “How accurate is XRF for different targeted metals?” This paper presents pairwise comparisons between XRF and Inductively Coupled Plasma Atomic Emission Spectrometer (ICP-AES) results for individual elements of Ni, Cu, Zn, Pb, Cd, Cr, Hg, and As. The portable XRF analyzer was used to estimate the concentration levels of eight heavy metal elements and then pairwise comparisons were made between XRF and ICP-AES results. Results presented in this paper suggest that XRF testing can be used as a screening technique with high confidence on samples where the first group of metal element (Pb, Zn, Ni, and Cu) concentrations is well in excess of the threshold limits. The order of reliability of the XRF measurements is Pb > Zn > Ni > Cu and their relative proximity ranges from 85%~35%. On the other hand, another group of metal elements which includes Hg, Cd, Cr, and As showed poor correlation. Their relative proximity ranges from 25%~2.3%.