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

Energy-dispersive X-ray fluorescence (EDXRF) measurements using three monochromatic excitations (W-L(beta):9.7 keV, Mo-K-alpha:17.4 keV and W-continuum:40 keV) have been established for the direct determination of trace heavy metals in light-element matrices. The detection limits are 0.08 similar to 0.64 mu g(-1) (Pb; 0.25 mu g g(-1), mean value; 0 .35 mu g g(-1)), ascertained for the 26 elements examined (V similar t o Pb and Bi). The precisions were found to be within 1% R.S.D. at 20 m u g g(-1) for all of the elements. The application of this method to t he heavy metals limit test (Japanese Pharmacopoeia, Japanese Standards of Cosmetic Ingredients) was investigated. The recoveries of Pb and h eavy metals in various standard samples were satisfactory. Compared wi th the conventional heavy metals limit test, the proposed method is mu ch easier to operate without sample preparation; furthermore, the dete ction limit, reproducibility and recovery are higher. The present EDXR F is useful as a rapid and simple substitute method (30 similar to 60 min) of the heavy metals limit test.