Unlike the standard cuvette of MILICHROM chromatographs, the fastening and sealing system of feeding capillaries has been modified. The infeed made acc. to the international standard, eliminates the appearance of air bubbles in the cuvette due to weak clamps and poor capillaries expansion, as well as allows using the detector together with imported analytical columns and fittings. Due to the reduction of extra-column erosion, efficiency of components separation by the device increases by approximately 1000 theoretical plates.