Spectrophotometric assay of hexamethylenetetramine

Abstract

The intense charge-transfer band in the ultraviolet spectra of the molecular complex of hexamethylenetetramine with iodine has been utilised in the sensitive spectrophotometric assay of this compound. From the various polar and halogenated solvents that were investigated, 1,2-dichloroethane and chloroform were selected. The hexamethylenetetramine-iodine complex has two peaks. Maximum intensity was attained at the shorter wavelength band, 273 nm, ε= 2.0 × 10⁴ l mol^–1 cm^–1 in 1,2-dichloroethane and 270 nm, ε= 1.6 × 10³ l mol^–1 cm^–1 in chloroform. The effect of time on the stability of the complex was investigated. A Job's plot of absorbance versus the molar ratio of hexamethylenetetramine to iodine indicated a 1 : 1 hexamethylenetetramine to iodine ratio. Accurate analysis of hexamethylenetetramine, free and in tablet form, in conjunction with cholic acid or potassium hydrogen phosphate, was possible by this method in the concentration range 1–12 µg ml^–1 of hexamethylenetetramine with a relative standard deviation of 0.005.