Diphenylamine In Solution Research Articles

Simultaneous determination of diphenylamine and nitrosodiphenylamine by photochemically induced fluorescence and synchronous fluorimetry using double scans method

A new synchronous fluorimetry in the combination with the photochemically induced fluorescence (PIF) method for simultaneous determination of nitrosodiphenylamine (NDPhA) and diphenylamine (DPhA) in aqueous and methanolic solution has been proposed. DPhA has a variety of applications and NDPhA is carcinogenic product of its. The method is based on the use of UV irradiation to produce fluorescent derivatives from NDPhA as a non-fluorescent molecule. The PIF properties of these amines in three media (water, methanol and acetonitrile) are reported. Because of their similar features, the fluorescence emission spectra of NDPhA photoproducts and DPhA were found to severely overlap in the whole wavelength region. Overlapping of conventional fluorescence spectra of these molecules is resolved by synchronous fluorometry using double scans method (SF-DS), thus making the use of separation techniques unnecessary for simultaneous determination of NDPhA and DPhA. The synchronous fluorescence intensity of NDPhA was measured at Δλ of 127 nm and at Δλ=75 nm for DPhA in solution, which are independent of each other. The best sensitivity can be achieved in water. The linear ranges for determination of NDPhA and DPhA were 1 × 10(-8) to 6 × 10(-6)molL(-1) and 4 × 10(-8) to 9 × 10(-6)molL(-1), and the limits of detection (LOD) were 8×10(-9) and 1 × 10(-8)molL(-1), respectively. The relative standard deviations (R.S.D.) of method is<3% (n=5). The proposed method was successfully applied for the determination of the two compounds in synthetic solutions, well water samples and also in gunpowder samples. The results obtained were favorably compared to those obtained with HPLC analysis.

A resonance Raman spectroscopic study of the protonation of 4-(phenylazo)-diphenylamine and 4-(4′-nitrophenylazo)-diphenylamine in solution and adsorbed on oxide surfaces

The adsorption of 4-(phenylazo)-diphenylamine (PADA) and 4-(4′-nitrophenylazo)-diphenylamine (Disperse Orange 1, DO1) on oxide surfaces has been studied by resonance Raman (RR) spectroscopy. The neutral and protonated forms of these molecules were modelled by ab initio calculations at the B3-LYP/DZ level, enabling calculation of the vibrational spectra of these species, together with vibrational assignments. Adsorption of PADA on silica-alumina and both PADA and DO1 on H-mordenite results in protonation, indicating the presence of Bronsted acidic sites on these oxide surfaces with pKa values ≤1.5. RR studies of the adsorption of PADA and DO1 can provide useful information regarding the nature of surface acidity on oxides which is complementary to that obtained from other probe molecules.

698. Molecular polarisation and molecular interaction. Part IV. The molecular polarisation of diphenylamine in solution in benzene, dioxan, and mixtures of benzene with nitrobenzene, triethylamine, and pyridine

698. Molecular polarisation and molecular interaction. Part IV. The molecular polarisation of diphenylamine in solution in benzene, dioxan, and mixtures of benzene with nitrobenzene, triethylamine, and pyridine