Example methods and apparatus for obtaining suspended particle information are disclosed. A disclosed example method includes emitting light from a light source, dividing the light source into a first path and a second path, and directing the first path to a first container comprising a plurality of particles in a suspension material. The example method also includes directing the second path to a second container containing a suspension material devoid of particles, retrieving a first transmission value of the first path through the first container, and retrieving a second transmission value of the second path through the second container. The example method further includes directing the first and second paths to the second and first containers, respectively, retrieving a third transmission value of the first path a through the second container, retrieving a fourth transmission value of the second path through the first container, and calculating a ratio of the first and second transmission values to the third and fourth transmission values to determine an indication of transmissivity for a given wavelength.