Question: What would the "cage-like" arrangement of Formazine molecules look like in a Formazine particle while it is still suspended in water? Would it be totally random, or have some kind of imperfect but recognizable regularity?
Formazine is used as an easily defined and prepared calibration or reference standard for turbidity measurements.
above x2: Formazine from PubChem.
Formazine (formazin) is a heterocyclic polymer produced by reacting hexamethylenetetramine with hydrazine sulfate.
The hexamethylenetetramine tetrahedral cage-like structure, similar to adamantane, serve as molecular building block to form a tridimensional polymeric network.
The readings shown by turbidimeters are not scaled in the measured light intensity, but in concentration of a reference suspension. Because the accuracy of this calibration solution determines the reliability of subsequent turbidity measurements, it is of crucial importance.
The internationally established turbidity standard for calibration is formazine. This standard can be reproduced at any time with the recipe taken from standard ISO 7027 (Water quality - Determination of turbidity).
It is extremely important to observe the prescribed preparation temperature, because it affects the particle size of the formazine particles perceptibly. The following Figure illustrates this. Errors caused by temperature variations are on the order of 1..2% per °C. Consequently, Sigrist keeps the preparation temperature constant to within ± 1°C.
above: "Particle size distributions of formazine at various preparation temperatures" from here.
above: Enlarged from TurbidityStandards.
above: Slide #10 from What is Turbidity? John Daly, ISA NorCal President, South Fork Instruments, Inc. Click for full size.