Antiparasitic drugs derived from macrocyclic lactones (MLs) are widely used in livestock activities around the world. An increasing concern for local authorities is the environmental pollution as a consequence of veterinary drugs widely used in rural areas. The purpose of environmental analysis is to monitor low levels of pollutant analytes in a large number of samples. Also, due to the lipophilic characteristic of these lactones, long-chain solvents are usually required for performing sample treatment before and during the analysis. Therefore, sensitive, specific, robust, and environmentally friendly analytical methods are still required. In this paper, a new automatized preconcentrationmethodology followed by microemulsion electrokinetic chromatography analysis was developed for the simultaneous separation and determination of the most used MLs, ivermectin (IVM) and moxidectin (MXD) in environmental water. XAD-4 resin was employed as an adsorbent for the pre-concentration process and ethanol was used as the eluent. In contrast to traditional analysis for IVM and MXD, in this methodology nonpolluting solvents were involved during the whole process and therefore, it could be considered as a contribution to green analytical chemistry. Under optimal experimental conditions, LOD obtained for IVM and MXD were of 3 x 10(-3) and 3.6 x 10(-3) mu g/L, respectively.