Relative evaluation of neutron activation, X-ray fluorescence and spark source mass spectrometry for multielement analysis of geothermal waters

Abstract

To sulfide geothermal waters from the French Pyrenees region and bicarbonate and chloride waters from the French Vosges area, all of the following analysis techniques were applied in order to compose a broad inventory of trace elements: (1) for the dissolved material: neutron activation analysis after a freeze-drying step using a very short cycle (I), short cycle (II) or long cycle (III), neutron activation after co-crystallization on 1-(2-pyridylazo)-2-naphthol (PAN) using a short cycle (IV) or long cycle (V), X-ray fluorescence after co-crystallization on PAN (VI) and spark source mass spectrometry after evaporation on graphite (VII) or preconcentration on PAN, and, (2) for the filtered or suspended material: neutron activation using a very short (VIII), short (IX) or long cycle (X) and X-ray fluorescence (XI). Altogether, on the average some 30 elements could be determined above the detection limit in solution and 15 in suspension. It appeared, however, that for procedures (I), (II), (IV), (VI), (VIII) and (XI) the investment of time and cost had not been efficient enough. Invoking only procedures (III), (V), (IX), (X) and for low salinity geothermal waters only: (VII), the number of elements detected was almost as large.