Field determination of trace concentrations of hazardous metals in waters by portable EDXRF

A new effective method has been developed for field determination of trace concentrations of cadmium, arsenic, zinc, copper, nickel, chromium, and lead in waters (e.g., surface and wastewater) using an energy dispersive X-ray fluorescence (EDXRF) analyzer. Trace concentrations cannot be determined by EDXRF without preconcentration. Agar was used for the preconcentration of these potentially toxic elements (PTE). Metals are trapped in the three-dimensional network of agar gel. Subsequent swelling of the gel leads to more effective preconcentration. The swollen gels with PTE were analyzed by a portable energy dispersive X-ray fluorescence analyzer Delta Professional X (pXRF). The preconcentration factors for each PTE were determined. With pXRF, the detection limits were 7, 5, 6, 7, 9, 47, and 22 µg/L for Cr, Ni, Cu, Zn, As, Cd, and Pb, respectively. A reference material was used to assess the methodology performance, and it has a very good agreement. The optimized and verified methodology was tested in practice at the special chemical unit of the Fire Rescue Service of the Czech Republic. PTE were determined by pXRF in a mobile chemical laboratory in field analysis. The measured values were compared with those determined via inductively coupled plasma mass spectrometry (ICP-MS) and were in good agreement. Our method was applied to real wastewater samples collected during after a fire of accumulation batteries of domestic photovoltaic power plants, allowing accurate real-time estimation of PTE concentrations. Obtaining reliable data during an ecological accident has a very important role in minimizing the subsequent environmental impact of the accident.