Highly sensitive inhibitory kinetics fluorescence method for determination of arsenic

A new and highly sensitive inhibitory kinetic fluorescence method for the determination of arsenic (III) has been established based on its inhibitory effect on the oxidation reaction of Acridine red (ADR) by KBrO(3) in sulphuric acid medium. The reaction has been followed by measuring the enhancement of fluorescence at 550 nm. It relies on the linear relationship where the change in the fluorescence (Delta F) versus added As(III) amounts in the range of 0-0.450 mu g mL(-1) is plotted, under the optimum conditions. The sensitivity of the proposed method, i.e. the limit of detection, is 2.1 x 10(-2) ng mL(-1). The method is featured with good accuracy and reproducibility for arsenic (III) determination. This method was successfully applied for the quantitative determination of arsenic (III) in food products samples, and the relative standard deviations and the recoveries were in ranges of 2.31-2.83% and 90.0-107.2%, respectively. A review of recently published catalytic or inhibiting kinetic methods for the determination of arsenic (III) has also been presented for comparison. The mechanism of reaction was studied.