Figures (8)  Tables (4)

    • Figure 1. 

      Fluorimetric system adjustable voltage source. (a) Schematic figure created with the Eagle program. (b) Board figure created with Eagle. (c) Photo of the electronic device.

    • Figure 2. 

      Design of the 3D device using the fluorimetric system, elaborated with the aid of the Rhinoceros 5 program.

    • Figure 3. 

      Photograph of the 3D fluorimetric system.

    • Figure 4. 

      Structure of quinine sulfate in diluted H2SO4 solutions.

    • Figure 5. 

      Emission spectra of quinine.

    • Figure 6. 

      Digital images of the blank and analytical standards.

    • Figure 7. 

      Analytical curve for quinine determination, constructed from the blue channel intensity values.

    • Figure 8. 

      Analytical curve for quinine determination, built from the mathematical processing standard vector of RGB intensities values.

    • Quinine/H2SO4 0.05 mol L−1
      (mg L−1)      		 R G B
      0 (Blank) 0 0 0
      0 (Blank) 0 0 0
      0 (Blank) 0 0 0
      2 0.29 0.26 24.25
      2 0.5 0.26 23.6
      2 0.42 0.24 24.31
      4 0.6 2.65 66.73
      4 0.57 2.92 66.87
      4 0.64 3.04 67.99
      6 0.6 10.01 104.05
      6 0.67 9.56 102.35
      6 0.66 9.67 103.41
      8 0.67 20.74 139.35
      8 0.65 20.84 139.99
      8 0.65 20.73 139.73
      10 0.66 34.5 170.52
      10 0.65 34.54 169.93
      10 0.68 34.19 170.65
      R: red; G: green; B: blue.

      Table 1. 

      Mean RGB intensities for blanks and analytical standards in triplicate.

    • Sample Repetitions (mg·L−1) DRP%
      Sample F 4.82 4.73 4.8 4.91 4.86 4.8 4.88 4.87 4.88 1.15
      Sample G 5.49 5.54 5.39 5.54 5.39 5.46 5.5 5.56 5.52 1.13

      Table 2. 

      Accuracy of the method verified in terms of DRP%.

    • Sample Proposed method
      (mg/100 g)      		 Luminescence PerkinElmer
      LS-50B (452 nm) (mg/100 g)
      A 55.0 ± 0.19 55.1 ± 0.01
      B 64.3 ± 0.02 64.2 ± 0.02
      C 47.8 ± 0.22 47.9 ± 0.02

      Table 3. 

      Accuracy of the proposed method.

    • Sample [Quinine] ± SD (mg·L−1)
      A 54.68 ± 0.29
      B 64.82 ± 0.24
      C 66.72 ± 0.23
      D 49.38 ± 0.38
      E 63.66 ± 0.25
      F 48.20 ± 0.40
      G 47.77 ± 0.43

      Table 4. 

      Quinine contents in commercial samples of tonic water, obtained in the application of the proposed method.