Electrophoresis is the movement of particles by electric force. In electrophoresis, charged particles are subjected to an electric field, causing them to migrate towards the electrode of opposite charge. This technique is commonly used for separating and analyzing molecules based on their size and charge.

Capillary electrophoresis (CE) is a specific type of electrophoresis that utilizes a narrow-bore capillary as a separation column. CE offers several advantages, including high separation efficiency, short analysis time, simple method development, and low sample and solvent consumption. However, one of the major drawbacks of CE is its poor detection sensitivity due to the small dimensions of the capillary. To overcome this limitation, proper sample cleanup and efficient sample preconcentration techniques can be employed before, during, or after sample loading into the capillary. Liquid phase microextraction techniques, coupled with CE, can enhance the sensitivity of detection without requiring significant modifications to existing CE instruments.

Photophoresis, on the other hand, refers to the movement of particles by optical force. In this phenomenon, particles experience a force when exposed to a gradient in light intensity or other optical properties. This force can cause the particles to move in a direction determined by the properties of the particles and the light field. In photophoresis of molecules, external fields are used to manipulate matter waves of molecules. By focusing a nonresonant IR laser pulse onto a molecular beam, a molecule-optical index of refraction can be obtained. This index can be used to separate a multi-component molecular beam into different components using a molecule prism composed of the laser field. The resolution achieved in the mentioned experiment was 0.62 for the spatial separation of a mixture beam of benzene and nitric oxide.