Sensor for use in highly sensitive analytical devices for qualitative and quantitative analysis of natural waters and technology-related solutions, containing low concentrations of components determined. Design of a sensor provides for simplification and costs reduction of its manufacture, widening range of solutions analyzed, improvement of their kinetic characteristics and increase in analysis sensitivity. Sensor has multichannel structure in a form of a piece 1 of a polycapillary tube with through capillaries forming microchannels filled up with two layers of immiscible substances. One layer (4) is formed of water or aqueous solution, and another layer (3) is formed of organic substance. The first of the layers in microchannels contains sorbent microgranules 5.