Determination of Ampicillin Based on Enhancement of Fluorescence Intensity of Amino-Functional Carbon Quantum Dots

Carbon quantum dots were prepared by hydrothermal method and amination on the surface by reaction with aqueous ammonia. After interaction with ampicillin, the fluorescence intensity of amino-functional carbon quantum dots (N-CQDs) was enhanced significantly. Base on this fact, a method for determination of ampicillin by fluorophotometry was established. In a colorimetric test tube, 1.00 mL of 0.016 mol·L^-1 N-CQDs solution, 0.45 mL of sample solution, 1 mL of Britton Robinson buffer solution (pH 7.0) were added successively, and the solution was diluted up to 5 mL. After reaction for 30 min at room temperature, the relative fluorescence intensity (F/F₀) was measured at excitation wavelength of 340 nm and emission wavelength of 433 nm. F, F₀ were the fluorescence intensity of the solution with and without the addition of N-CODs. Linear relationship was found between relative fluorescence intensity and concentration of ampicillin in the range of 2.0×10^-6-9.0×10^-5 mol·L^-1, with detection limit (3S/N) of 1.2×10^-6 mol·L^-1. Values of recovery obtained by standard addition method in the range of 99.0%-109% and RSDs (n=5) were less than 2.0%.