Can turbidity be measured in coloured samples?
Turbidity can be measured in coloured samples provided the correct type of instrument is used. There are 2 different light sources that are used in nephelometers –infra-red (IR) light at 860nm or broad-spectrum ultraviolet-visible light (UV-Vis). IR light (generally produced by diodes) has the advantage of being outside the visible range, and any sample coloration cannot have any interference effect. UV-Vis light (from tungsten lamps) irradiates the complete spectrum thus sample colour will affect any measurement in the range in which the coloration absorbs. If turbidity measurements are required in a coloured sample then a nephelometers with an IR light source should be used.
