The Use of 7,7', 8,8'-Tetracyanoquinodimethane for the Spectrophotometric Determination of Some Primary Amines Application to Real Water Samples

摘要

A sensitive, simple, and accurate spectrophotometric method was developed for the quantitative determination of some primary aliphatic and aromatic amines, that is, ethylamine, 1,2-diaminopropane, aniline, p-aminophenol, and benzidine. The method is based on the interaction of these amines in aqueous medium with 7,7', 8,8'-tetracyanoquinodimethane (TCNQ) reagent in the presence of a buffer solution and surfactant (in the case of aromatic amines) to form charge-transfer complexes measurable at maximumwavelengths ranging between 323 and 511 nm. Beer's law is obeyed over the concentration ranges of 0.025 and 3.0 μg/mL and the molar absorptivity is ranged between 8.977 × 10~3 and 5.8034 × 10~4 L?mol~(?1)?cm~(?1) for these amines.Themethod was applied for the determination of benzidine in the river, sea, and tap waters.The TCNQ complexes with the previously mentioned amines were formed in the ratio of 1: 1 amine: TCNQ, and their stability constants ranged between 8.78 × 10~4 and 1.844 × 10~5 L?mol~(?1).