SPECTROPHOTOMETRIC DETERMINATION OF THIOCYANATE WITH RHENIUM

Numerous spectrophotometric procedures are available for the determination of the thiocyanate ion but each method suffers from serious interferences or some other undesirable feature. A few selected examples of the more widely applied existing systems and their undesirable aspects include: (a) the iron(III)-thiocyanate complex systems (1-3) is limited by color instability problems and a variety of interferences (b) the copper-pyridine (4-6) and the methylene blue (7) systems require an extraction step and are susceptible to many interferences (c) the benzidine-pyridine systems (8, 9) exhibit color instability and a very serious objection to all methods using benzidine has arisen because benzidine has been shown to be carcenogenic (3). No previous use of the rhenium-thiocyanate interaction to determine thiocyanate was found. This paper reports the results of a study carried out with the objective of developing a simple, sensitive, spectrophotometric method for determining thiocyanate that would circumvent many of the problems associated with existing methods. © 1969, American Chemical Society. All rights reserved.