I'm doing an elemental analysis of soils using an XRF Analyzer, the results obtained are in ppm. My question is, can I directly convert values from ppm to mg/Kg of soil?
Yes, it does. Just be aware of the basis on which results are expressed, e.g. "dry basis" or "as received basis" and/or "material passing the 2mm sieve" etc. , especially when it comes to interpretation of results and when comparing with regulatory limits.