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 BORON CARBIDE: METHOD 7506, Issue 2, dated 15 August 1994 - Page 6 of 7 APPENDIX: INTERFERENCES When using copper K α X-radiation, titanium dioxide (anatase) and the primary peak of silver interfere with the primary boron carbide peak; therefore, no measurements can be done with either the primary boron carbide or the silver peak. The secondary boron carbide peak is chosen as the analytical peak if no other interferences are present. The secondary titanium diboride peak interferes to a small extent with the secondary boron carbide peak. The primary titanium diboride peak interferes with the secondary silver peak. Niobium oxide interferes with the tertiary boron carbide peak. Silver chloride, found as an impurity in the silver filter, may interfere with some low-intensity boron carbide peaks. When peak overlaps are not severe, a smaller receiving slit or chromium X-radiation may be used; however, a new calibration graph will be necessary. The presence of some elements in the sample (iron, in particular) can result in appreciable X-ray fluorescence, leading to high background intensity. This can be minimized by a diffracted beam monochromator. The interfering effects of X-ray absorption by the sample result in attenuation of the diffracted beam and correction must be made (step 12 and Table 1).

NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94