Spectrophotometric study of the charge transfer complexes of some pharmaceutical butyrophenones.
The molecular interactions between haloperidol and droperidol as electron donors and each of iodine; 7,7,8,8-tetracyanoquinodimethane (TCNQ); 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ); tetracyanoethylene (TCNE); 2,4,7-trinitro-9-fluorenon (TNF); and 2-3-5-6-tetrabromo-1,4-benzoquinone (Bromanil) as acceptors have been investigated spectrophotometrically. Different variables affecting the reaction were studies and optimized. Beer's law was obeyed in a concentration limit of 2.5-2500 mug ml(-1) for the studied drugs with various acceptors used. Electron affinities (E(A)) of the acceptors were found to correlate with both the time required for maximum colour formation and the molar absorptivities of haloperidol and droperidol. A Job's plot of the absorbance versus the molar ratio of the drugs to iodine indicated 1:1 ratio. The proposed methods were found to be rapid and sensitive and may be applied for estimation of named drugs in pharmaceutical dosage forms without interferences from the common additives encountered. Percentage recoveries ranged from 99.1-102.2%.
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Pharmaceutical Analytical Chemistry Department, Faculty of Pharmacy, Assiut University, 71 526-Assiut, Egypt.