Capillary electrophoresis CE is a powerful analytical technique used to separate and analyze complex mixtures of ions and molecules based on their size, charge, and shape. It is particularly useful for the analysis of small ions, biomolecules, and pharmaceuticals. The technique involves the application of an electric field across a narrow capillary filled with a running buffer, which causes the ions and molecules in the sample to migrate through the capillary at different rates depending on their electrophoretic mobility.To determine the composition of a sample containing multiple ions and molecules using capillary electrophoresis, the following steps can be taken:1. Sample preparation: The sample should be prepared in a suitable solvent and concentration to ensure that the ions and molecules are in a suitable form for analysis.2. Selection of running buffer: The running buffer plays a crucial role in the separation process. Factors to consider while selecting the running buffer include pH, ionic strength, and the presence of additives such as surfactants or chelating agents. The pH should be chosen based on the pKa values of the analytes to ensure that they are in the desired charged state. The ionic strength should be optimized to provide adequate buffering capacity and to minimize Joule heating. Additives can be used to improve the separation of analytes with similar electrophoretic mobilities.3. Capillary selection: The choice of capillary dimensions, material, and coating can significantly affect the separation efficiency and resolution. Fused silica capillaries are commonly used due to their low cost, high transparency, and chemical inertness. The inner diameter and length of the capillary can be optimized based on the desired separation efficiency and analysis time.4. Optimization of separation parameters: The applied voltage, temperature, and injection time can be optimized to achieve the best separation and resolution of the analytes. Higher voltages can lead to faster separations but may also cause increased Joule heating and band broadening. Temperature control is essential to minimize the effects of Joule heating and to maintain consistent separation conditions.5. Choice of detector: The choice of detector depends on the analytes' properties and the desired sensitivity and selectivity. Common detectors used in capillary electrophoresis include UV-Vis absorbance, fluorescence, and mass spectrometry. The choice of detector can significantly affect the accuracy and sensitivity of the analysis. For example, fluorescence detection can provide high sensitivity and selectivity for analytes that are naturally fluorescent or can be derivatized with a fluorescent tag. Mass spectrometry can provide high sensitivity and structural information for the identification and quantification of analytes.6. Data analysis: The obtained electropherogram can be used to identify and quantify the various species present in the sample based on their migration times and peak areas. The migration times can be compared to those of known standards to identify the analytes, while the peak areas can be used to determine their concentrations using calibration curves or internal standards.In summary, capillary electrophoresis can be used to determine the composition of a sample containing multiple ions and molecules by optimizing the running buffer, capillary, separation parameters, and detector. The obtained information can be used to identify and quantify the various species present in the sample, providing valuable insights into the sample's composition and properties.