A method of liquid chromatography includes providing an injection valve, drawing a sample and a diluent while mixing, pushing the mixed sample and diluent onto a sample loop of the injection valve, and injecting the mixed sample and diluent. An analytical apparatus includes a proportioning unit, an injection valve having a sample loop, and a sample pump. The injection valve has a draw state and a load state, and has a port in fluidic communication with an outlet port of the proportioning unit. The sample pump is in fluidic communication with the outlet port of the proportioning unit, if the injection valve is in the draw state, to draw both a sample and a diluent through the proportioning unit and the injection valve, and in fluidic communication with the sample loop, if the injection valve is in the load state, to push the drawn sample and diluent onto the sample loop.