DETERMINATION OF SODIUM GLUTAMATE BY THIN LAYER CHROMATOGRAPHY METHOD WITH FLUORESCENT DETECTION

Abstract

The spectral and luminescent properties of Tb(III) complex with ciprofloxacin and monosodium glutamate (MSG) were studied. The stoichiometric composition of complex (Tb(III) : ciprofloxacin : MSG = 1:2:1) was determined by the Bent-French method. Its spectral and luminescent characteristics in the phase of sorbent (the maximum wavelength of the luminescence and luminescence excitation, the lifetime of luminescence) were defined. It was established that effective energy transfer takes place from the ligand excited state to lanthanide ion in Tb(III) – ciprofloxacin – MSG complex resulting in intensive sensitized luminescence. The optimal conditions of chromatographic separation of monosodium glutamate (stationary and mobile phase, the sample volume applied to the plate, the optimal concentration of a luminescent detection reagent (Tb(III), ciprofloxacin, MSG) were selected. The maximal luminescence intensity was occurred at 1·10–3 mol/L Tb (III) in neutral solutions at pН 6,5 – 7,5. The maximal luminescence intensity of Tb(III) – ciprofloxacin – MSG complex was observed at 2.10-3 mol/L ciprofloxacin and at 1·10–3 mol/L MSG. A thin layer chromatography method for determining of monosodium glutamate in dried squids with using Tb (III) – ciprofloxacin as a fluorescent detection reagent has been proposed. Sodium glutamate was found in all commercial samples of dried squid. This means that some manufacturers do not indicate the presence of this food additive on the label of the products in the ingredient list in any packaged food in contrast of food labeling law.