What is the best wavelenth to use for a turbidemetric assay?
Particle agglutination assays for quantitative determinations can be very sensitive and specific. In general, sensitized particles are reacted with a sample to undergo a degree of agglutination that is proportional to the concentration of analyte in the sample. Particle agglutination is accompanied by a change in the amount of light scattering. Increased light scatter may be detected in spectrophotometers as in increase in absorbance. The maximum amount of light scattering and therefore the maximum absorbance change is obtained when the scattering particles are about the same size as the wavelength of light being scattered. If the particles are very much larger or smaller than the wavelength of the scattered light the absorbance signal will decrease. In order to take advantage of this relationship it is useful to use a wavelength that is two to three times that of the monodisperse particle diameter. So for particles of 200 to 300 nanometers, wavelengths of 500 to 700 nm should be chose
