Determination of α-Naphthol and β-Naphthol in water samples by capillary electrophoresis coupled with large volume sample stacking

A simple, fast, and efficient on-line pre-concentration based on large volume sample stacking (LVSS-CE) was developed for the determination of α-Naphthol, and β-Naphthol (α-NAP and β-NAP) in complex matrices. Parameters that affect the analytical performance of LVSS were systematically optimised using a Box-Behnken design (injection time, pre-concentration time, and voltage of reverse polarity). Under the optimal conditions of injection time (180 s), pre-concentration time (180 s), and voltage of reverse polarity (−6 kV), the sensitivity was improved 25.9 and 38.8-fold for α-NAP and β-NAP in comparison to CE-UV. The detection limits for α-NAP and β-NAP were 6.56 and 4.63 µg L−1, and the method was successfully applied in drinking and tap water samples with recoveries from 92.98 to 97.46 with RSD less than 10.00% in all cases.