▎ 摘　　要

Oxygenated graphene quantum dots (GQDs) were prepared and used as a new colorimetric reagent for analysis of pharmaceutical amines. Citric acid was thermalized to prepare GQDs with functional groups along their edges. The prepared GQDs were used as a coupling reagent in an azo dye formation for dapsone (DAP) and metoclopramide (MET) determination. The characterization was done by scanning electron microscopy, transmission electron microscopy, atomic force microscopy, X-ray diffraction spectroscopy, Energy dispersive X-ray spectroscopy, EDX-mapping, dynamic light scattering, photoluminescence spectroscopy, Raman and FT-IR spectroscopy. DAP and MET were diazotized by nitrite to their related diazonium cations in acidic condition through a flow injection manifold. Then they were coupled to GQDs to produce the yellow colored products. Detection of the products was performed by spectrophotometry at 423 nm. Various chemical and instrumental parameters were optimized by a univariate procedure and a central composite design (CCD) chemometrics approach. The analytical method showed the linear calibrations for DAP and MET in the ranges of 0.03-20 and 0.1-40 mu g mL(-1), respectively. The limit of detection for both DAP and MET was of 0.01 mu g mL(-1), respectively. The inter-day experiments showed a satisfactory robustness of the method for determination of DAP and MET. The sample throughput found in this method was about 60 h(-1). Lake, river and well water samples as well as soil samples along with some pharmaceutical formulations were analyzed. (C) 2018 Elsevier Ltd. All rights reserved.