Enhanced Indirect fluorescence detection of p-nitrophenol, 2,4-dinitrophenol and Trinitrophenol by micellar electrokinetic capillary chromatography with in-column optical-fiber LED-induced fluorescence detection

Enhanced indirect fluorescence detection with in-column optical-fiber LED-induced fluorescence (LED-IF) detection has been developed for the simultaneous separation and determination of p-nitrophenol, 2,4-dinitrophenol and trinitrophenol. The instrumental set-up is simple, cost-effective and the detection method is stable. Different experimental parameters have been studied. The optimum conditions were determined as: running buffer (pH 9.1) composed of 10 mM borate, 80 mM sodium dodecylsulfate and 0.18 μM fluorescein (as a background reagent); applied voltage of 15 kV; working temperature of 25.0°C. The limits of detection (S/N = 3) were 11, 18 and 16 μM for p-nitrophenol, 2,4-dinitrophenol and trinitrophenol, respectively. The nitrophenols were completely separated in 13 min and the number of theoretical plates for p-nitrophenol, 2,4-dinitrophenol and trinitrophenol were 8.1 × 10 ⁶ , 6.5 × 10 ⁶ and 8.4 × 10 ⁶ , respectively. The RSDs (n = 6) for the migration time and the peak area were better than 0.85 and 0.91%, respectively. Our proposed method possesses the advantages of rapidness and good separation efficiency.