Spectrophotometric and fluorimetric determination of hexamine in pure form and its pharmaceutical formulation

Ethyl acetoacetate and methyl acetoacetate have been tested for the determination of hiprex (methenamine hippurate). Both the esters react with hexamine and hiprex forming fluorescent yellow Hantzsch esters. The products show absorption maximum at 370 nm and a fluorescence emission maximum at 465 nm in aqueous n-propanol. Important parameters such as pH, temperature, mole ratio and time of reaction have been optimized. The co-efficient of variation for inter and intra-day precisions were less than 1%. The chromogens show linearity in the concentration ranges of 2.0-35.0 microg x ml(-1) and 0.6-40.0 micro-1) for the spectrometric and fluorimetric determinations of hiprex, respectively.