An alternative methodology for simultaneous analysis of aspartame (ASP), cyclamate (CYC), saccharin (SAC) and acesulfame-K (ACE) by capillary zone electrophoresis was developed and validated. Optimum separation conditions were achieved by evaluation of the effective mobility curve followed by background electrolyte (BGE) optimization through a full 32 factorial design. The optimized electrolyte composed of 20.0 mmol L−1 sodium tetraborate, 15.0 mmol L−1 Tris and 7.5 mmol L−1 benzoic acid (pH 9.15) was suitable for simultaneous direct (ASP, ACE and SAC) and indirect (CYC) UV detection at 215 nm. Method performance was evaluated for linearity (r > 0.992), precision (RSD%: <4.0%, ASP; <3.0%, CYC; <4.5%, SAC and <4.5%, ACE), accuracy (mean recovery range: 101.2%, ASP; 102.2%, CYC; 91.9%, SAC and 94.4%, ACE), detection limit (expressed in mg L−1: 6.80, ASP; 12.0, CYC; 0.50, SAC and 3.30, ACE) and quantification limit (expressed in mg L−1: 22.0, ASP; 40.0, CYC; 1.60, SAC and 10.0, ACE). Method applicability was demonstrated by analysis of lemon tea sachet samples containing ASP, CYC, SAC and ACE.