ELEMENTAL ANALYSIS OF LIQUIDS BY EXTERNAL BEAM PIXE DOWN TO PPB LEVEL

A method is reported for the direct elemental analysis of solutions and liquids by PIXE, utilizing the external proton beam facility at the Van de Graaff accelerator of the Atomic Energy Centre, Dacca. The samples were irradiated in liquid form through a thin Mylar window holding the liquid in a small polyethylene cup. The proton beam was allowed to pass from the vacuum into the air through a 7 μm Be window, then through an air path of 23 mm and the Mylar window of the sample cup, into the solution. Mylar windows up to 1 mg/cm2 in thickness were used. The X-rays were detected at 90° relative to the beam with a Si(Li) detector. Minimum detection limits and efficiency curves are reported, and the behaviour of some ions during irradiation is discussed. It is shown that under favourable conditions the sensitivity of the method can reach the ppb level. © 1979.