Figure 2: Application of the developed CZE-ID method to spiked and nonspiked extracts from a) beetroot b) spinach. Peak identification; 1. proline 2. betaine. Experimental conditions as reported in Figure 2. Concentration of proline in spiked (51mg/L) and non-spiked (0.9 mg/L) and betaine in spiked (150 mg/L) and non-spiked (104 mg/mL) spinach extract. Concentration of proline in spiked (50 mg/L) and non-spiked (not detected) and betaine in spiked (191 mg/L) and nonspiked (145 mg/mL) beetroot extract. Reprinted from Ref. [7], with permission.