Kit for dispensing fluids

The subject of the present invention is a metering valve which comprehends: a movable insert which is a tube in which at least two separators delimit at least a defined portion of said tube bolus portion, where said bolus portion defines a volume which is the volume to be dispensed, or bolus, characterized by the fact that on the surface lateral of said portion-bolus open two holes, an inlet hole and an outlet hole; a body which includes internally: at least one dispensing channel, where said channel dispenser passes through said body and has an open inlet towards the environment external to said body, suitable for accommodating said insert mobile; at least four channels, two for input and two for output which are in fluid communication with said channel dispenser and with the environment external to said body; where said movable insert is made of a material which has a different stiffness of the material with which it comes into contact when inserted into said channel dispenser. A further object of the present invention is a method for the controlled dispensing of fluids in microfluidic systems.