RAPID ANALYSIS FOR THE ARSENIC LIMIT TEST BY ENERGY-DISPERSIVE X-RAY-FLUORESCENCE ANALYSIS WITH MONOCHROMATIC EXCITATION

Energy-dispersive X-ray fluorescence (EDXRF) measurements using the mo nochromatic excitation of a Mo-K-alpha X-ray tube (17.44 keV) have bee n established for the direct determination of trace arsenic. A detecti on limit of 0.08 mu g g(-1) in light-element matrices was obtained, an d the relative standard deviation for ten determinations of 2 mu g g(- 1) arsenic is 1.2%. The application of the proposed method to the arse nic limit test (Japanese Pharmacopoeia, Japanese Standards of Cosmetic Ingredients) was investigated. The recoveries of arsenic in various s amples were satisfactory. Compared with the conventional arsenic limit test, the proposed method is much easier to operate because sample pr eparation is unnecessary; furthermore, the detection limit, reproducib ility and recovery are higher. The EDXRF method is useful as a rapid s ubstitute method (30 min) of the arsenic limit test.