3.3. Method validation
Investigation of NaDC concentration has shown that the opti-mal concentration could be 80 mM, which provides about 1.5- to 2-fold better result in comparison with that of 120 mM. However, when it was applied to the real sample, a baseline separation between the tested compounds and unknown substances wasn't achieved for the lower separation efficiency. As a compromise for selectivity and sensitivity, 120 mM was chosen for real sample