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

Table 1

Effect of buffer solutions on the absorbance of aromatic amine-TCNQ complexes.

Type of buffer solution	Absorbance of TCNQ complex with
	p-Aminophenol*; (5 μg/mL)	Benzidine; (1.5 μg/mL)	Aniline; (2.5 μg/mL)
Without	0.366	0.254	0.155
Na2CO3 + NaHCO3	0.590	0.368	—
H3BO3 + NaOH	0.612	0.363	—
Na2B4O7 + NaOH	0.713	0.328	—
KH2PO4 + KOH	0.696 (0.716**)	0.388	0.220
NH4Cl + NH4OH	0.695	—	—
Citric acid + sodium citrate	—	—	0.185
Na2B4O7 + HCl	—	—	0.200
NaCl + Na2B4O7 + H3BO3	—	—	0.216

∗Absorbance at 460 nm.
∗∗Absorbance at 475 nm.