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 (130, 131, 132) 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 (121, 122, 123) for conveying fluids (10, 20, 30) within the apparatus, wherein the at least one pump device (121, 122, 123) 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 (130, 131, 132) 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 (121, 122, 123) for conveying fluids (10, 20, 30) within the apparatus, wherein the at least one pump device (121, 122, 123) 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.