Summary. A method was developed for the determination of
insecticidal ‘inert dusts’, particularly the diatomaceous earth
product Dryacide, on grain. The method was also evaluated for another physical
insecticide, magnesite, and 2 standard clays, bentonite and kaolin. The method
consists of isolation of dusts (both inert dust and grain dust) from grain,
followed by density centrifugation and ashing of the bottom pellet. The ash
content of the bottom pellet is linearly related to the percentage inorganic
dust in grain dust (w/w). The method can serve 2 functions. First, it can
quantify total inorganic ash. Second, it can quantify the total amount of a
specific inorganic additive, for example, Dryacide, thus enabling studies on
the fate of inorganic additives during grain processing.