Development of Micellar HPLC-UV Method for Determination of Pharmaceuticals in Water Samples

Figure 3

Effect of the pH gradient on the analyte separation. Gradients: (a) 7.0 min, (b) 5.0 min, (c) 2.0 min, and (d) isocratic until 2.0 min. Data were obtained for standard solution of amoxicillin (1), caffeine (2), tetracycline (3), diclofenac (4), ibuprofen (5), 17α-ethynylestradiol (6), levonorgestrel (7), nimesulide (8), ciprofloxacin (9), and norfloxacin (10) in the concentration of 20.0 mg·L⁻¹, with an injected volume of 20 μL, at a flow rate of 1.0 mL·min⁻¹, at 25°C, and detection at 220 nm. Mobile phase contains 15.0% (v/v/) ethanol, 3.0% (m/v) SDS, and 20.0 mmol·L⁻¹ of phosphate at pH 7.0 (phase A) and pH 8.0 (phase B). A in the y-axis is the absorbance.