Microfluidic apparatus for processing and aliquoting a sample liquid , wherein the microfluidic apparatus has the following features: a division chamber for accommodating an input volume of the sample liquid , wherein the division chamber has a plurality of cavities for accommodating partial volumes of the sample liquid that are usable for detection reactions, wherein the plurality of cavities represent an aliquoting structure; a microfluidic network for making the division chamber accessible in fluid-mechanical fashion, wherein the microfluidic network has at least one feed channel , a removal channel which is connected to the division chamber in fluid-mechanical fashion, at least one channel branching point of the feed channel into a discharge channel and a supply channel which is connected to the division chamber in fluid-mechanical fashion, and at least one valve for influencing a fluid flow in the region of the channel branching point , wherein there is a reduction in the spatial dimensions of the liquid-conducting structures at the transition to the division chamber ; and at least one pump device for conveying fluids within the apparatus , wherein the at least one pump device and the microfluidic network are designed to convey the sample liquid as a first phase through the microfluidic network into the division chamber , in order to arrange partial volumes of the sample liquid in the cavities , and to convey a sealing liquid as a second phase through the microfluidic network into the division chamber , in order to seal the partial volumes of the sample liquid in the cavities using the sealing liquid , wherein the apparatus is formed so as to pre-store the sample liquid and the sealing liquid outside of the division chamber , wherein the sample liquid and the sealing liquid already comprise a common boundary interface during the transport to the aliquoting structure and the filling of the cavities with the sample liquid . a division chamber for accommodating an input volume of the sample liquid , wherein the division chamber has a plurality of cavities for accommodating partial volumes of the sample liquid that are usable for detection reactions, wherein the plurality of cavities represent an aliquoting structure; a microfluidic network for making the division chamber accessible in fluid-mechanical fashion, wherein the microfluidic network has at least one feed channel , a removal channel which is connected to the division chamber in fluid-mechanical fashion, at least one channel branching point of the feed channel into a discharge channel and a supply channel which is connected to the division chamber in fluid-mechanical fashion, and at least one valve for influencing a fluid flow in the region of the channel branching point , wherein there is a reduction in the spatial dimensions of the liquid-conducting structures at the transition to the division chamber ; and at least one pump device for conveying fluids within the apparatus , wherein the at least one pump device and the microfluidic network are designed to convey the sample liquid as a first phase through the microfluidic network into the division chamber , in order to arrange partial volumes of the sample liquid in the cavities , and to convey a sealing liquid as a second phase through the microfluidic network into the division chamber , in order to seal the partial volumes of the sample liquid in the cavities using the sealing liquid , wherein the apparatus is formed so as to pre-store the sample liquid and the sealing liquid outside of the division chamber , wherein the sample liquid and the sealing liquid already comprise a common boundary interface during the transport to the aliquoting structure and the filling of the cavities with the sample liquid . <EOS>