The EM ColorpHast pH Indicators offer a convenient method for accurate colorimetric pH indication. They feature covalently bound indicator dyes so they will not bleed even in strong alkaline solutions. The strips can be immersed in samples for extended periods, so even weakly buffered solutions can be accurately tested without contaminating the sample.
The universal strip tests the full 0-14 pH range with a sensitivity of 1 pH unit. The intermediate range indicators provide a sensitivity of 0.3-0.5 pH units and narrow range stips provide a sensitivity of 0.2-0.3 pH units.