中性子放射化分析用試料の粉砕に際して混入する元素とその量について

Maximum contamination levels for INAA (instrumental neutron activation analysis) elements during crushing samples were evaluated. Four clear quartz crystals were crushed using variable combinations of steel, agate and tungsten carbide equipments, which are hand-operated barrels, a moter-driven mill and a centrifugal ball mill.
From the steel barrel, Fe and Co were introduced. From the agate mill, no INAA elements was detected to have contaminated. From the tungsten carbide mills, W, Ta, Co and Sc were introduced, and minor afnount of Cr was also detected to have introduced from the ball mill.
Supposing from the ratios among each of contaminants from tungsten carbide mills, and the usual contamination levels of W in natural igneous rocks, usage of tungsten carbide mills should be restricted only to crush the samples which originally contain sufficient amounts of such element that are possibly introduced, to an coarse grain size (Max. 1 mm) by rapping chips by hand.