Black Gridded, Sterile. Whatman black and green mixed ester membranes are composed of cellulose acetate (-20%) and cellulose nitrate (-80%). These membranes are characterized by a smoother and more uniform surface than pure nitrocellulose filters.
Membrane circles white, 50 mm, mixed esters, 0.45 um, 3.1 mm black grid, sterile. In these products the microorganism counts are very low and are therefore determined quantitatively via enrichment methods.