Phosphotungstic Acid Negative Stain Solution (2%)

Negative staining, discovered by Hall, is a technique that contrasts with conventional positive staining. The principle involves using heavy metal salts to encase the sample, which has low electron density. This enhances the electron density of the surrounding medium, creating 'mass-thickness' differences between fine structures and increasing scattering/absorbing contrast. Consequently, the sample appears as a bright structure against a dark background. Common negative stains include Phosphotungstic Acid (PTA), Ammonium Molybdate, and India Ink. The most widely used one is 1-3% Phosphotungstic Acid.

Specifically, 2% Phosphotungstic Acid Negative Stain Solution is suitable for visualizing macromolecules, bacteria, viruses, protozoa, bacteriophages, organelles, nucleic acids, protein crystals, and other biological specimens. Following staining, the specimen exhibits a clear, bright appearance, while the background remains black.