Biomaterial Database

Kinetic spectrophotometric method for trace determination of thiocyanate based on its inhibitory effect. 2010

Radhey M Naik, and Basant Kumar, and Abhas Asthana

Department of Chemistry, University of Lucknow, Lucknow, India. naik_rm@rediffmail.com

A kinetic spectrophotometric method for the determination of thiocyanate, based on its inhibitory effect on silver(I) catalyzed substitution of cyanide ion, by phenylhydrazine in hexacyanoferrate(II) is described. Thiocyanate ions form strong complexes with silver(I) catalyst which is used as the basis for its determination at trace level. The progress of reaction was monitored, spectrophotometrically, at 488 nm (lambda(max) of [Fe(CN)(5)PhNHNH(2)](3-), complex) under the optimum reaction conditions at: 2.5x10(-3)M [Fe(CN)(6)](4-), 1.0x10(-3)M [PhNHNH(2)], 8.0x10(-7)M [Ag(+)], pH 2.8+/-0.02, ionic strength (mu) 0.02 M (KNO(3)) and temperature 30+/-0.1 degrees C. A linear relationship obtained between absorbance (measured at 488 nm at different times) and inhibitor concentration, under specified conditions, has been used for the determination of [thiocyanate] in the range of 0.8-8.0x10(-8)M with a detection limit of 2x10(-9)M. The standard deviation and percentage error have been calculated and reported with each datum. A most plausible mechanistic scheme has been proposed for the reaction. The values of equilibrium constants for complex formation between catalyst-inhibitor (K(CI)), catalyst-substrate (K(s)) and Michaelis-Menten constant (K(m)) have been computed from the kinetic data. The influence of possible interference by major cations and anions on the determination of thiocyanate and their limits has been investigated.

UI	MeSH Term	Description	Entries
D009994	Osmolar Concentration	The concentration of osmotically active particles in solution expressed in terms of osmoles of solute per liter of solution. Osmolality is expressed in terms of osmoles of solute per kilogram of solvent.	Ionic Strength,Osmolality,Osmolarity,Concentration, Osmolar,Concentrations, Osmolar,Ionic Strengths,Osmolalities,Osmolar Concentrations,Osmolarities,Strength, Ionic,Strengths, Ionic
D010659	Phenylhydrazines	Diazo derivatives of aniline, used as a reagent for sugars, ketones, and aldehydes. (Dorland, 28th ed)
D002384	Catalysis	The facilitation of a chemical reaction by material (catalyst) that is not consumed by the reaction.	Catalyses
D003486	Cyanides	Inorganic salts of HYDROGEN CYANIDE containing the -CN radical. The concept also includes isocyanides. It is distinguished from NITRILES, which denotes organic compounds containing the -CN radical.	Cyanide,Isocyanide,Isocyanides
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D006863	Hydrogen-Ion Concentration	The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH	pH,Concentration, Hydrogen-Ion,Concentrations, Hydrogen-Ion,Hydrogen Ion Concentration,Hydrogen-Ion Concentrations
D012463	Saliva	The clear, viscous fluid secreted by the SALIVARY GLANDS and mucous glands of the mouth. It contains MUCINS, water, organic salts, and ptylin.	Salivas
D013053	Spectrophotometry	The art or process of comparing photometrically the relative intensities of the light in different parts of the spectrum.
D013696	Temperature	The property of objects that determines the direction of heat flow when they are placed in direct thermal contact. The temperature is the energy of microscopic motions (vibrational and translational) of the particles of atoms.	Temperatures
D013861	Thiocyanates	Organic derivatives of thiocyanic acid which contain the general formula R-SCN.	Rhodanate,Rhodanates