A sensitive method for determination of trace amounts of chromate (III) with terbium (III) sodium hexametaphosphate chelate as fluorescent probe.

Based on the fluorescence quenching of Terbium (III)-sodium hexametaphosphate (Tb/SHMP) chelates in the presence chromate (III), a sensitive fluorimetric method was developed for the determination of trace amounts of chromium (III) in aqueous solutions. Under the optimum conditions, the linear calibration graph was obtained (R = 0.996). The linear range and detection limit of Cr (III) were 7.69 × 10(-7) to 1.15 × 10(-4) mol L(-1) and 4.50 × 10(-7) mol L(-1), respectively. The proposed method had a wider linear range and was proved to be very sensitive, rapid and simple. The method was applied successfully to the determination of chromium (III) in the synthetic samples and real water samples. Moreover, the reaction mechanism was discussed through the fluorescence lifetime and proved to be dynamic quenching behavior.