Microfluidic flow filtration system for increasing the concentration of components contained in a fluid sample having a recirculation loop fluid circuitry , the fluid circuitry comprising the following elements: - a tangential flow filtration element having a feed inlet , a retentate outlet , a permeate outlet and a membrane capable for separating the fluid sample into a retentate stream and a permeate stream upon passage of the fluid sample into the tangential flow filtration element through the feed inlet , - an element for pumping for creating and driving a fluid flow of the fluid sample through the fluid circuitry and the tangential flow filtration element , - at least two elements for obtaining information about the properties of the fluid sample within the fluid circuitry ; and - a plurality of conduits connecting the elements to the fluid circuitry through which a fluid stream of the fluid sample is conducted; wherein the minimal working volume of the fluid circuitry being defined by the minimal fluid volume retained in the elements and the conduits , such that the fluid can be recirculated in the fluid circuitry without pumping air through the fluid circuitry , is at most 5 ml, - the functionality of at least two elements of the group of elements of the circuitry is integrated in one integrated microfluidic element , - the one integrated microfluidic element defines a volume element having a volume which is at most one fourth of the minimal working volume of the fluid circuitry , - the integrated microfluidic element integrates the functionality of at least two elements for obtaining information about the properties of the fluid sample, and - one element for obtaining information about the properties is an optical measuring element for determining the concentration of the components contained in the fluid sample and - one element for obtaining information about the properties is a measuring element for determining the viscosity of the fluid sample. - a tangential flow filtration element having a feed inlet , a retentate outlet , a permeate outlet and a membrane capable for separating the fluid sample into a retentate stream and a permeate stream upon passage of the fluid sample into the tangential flow filtration element through the feed inlet , - an element for pumping for creating and driving a fluid flow of the fluid sample through the fluid circuitry and the tangential flow filtration element , - at least two elements for obtaining information about the properties of the fluid sample within the fluid circuitry ; and - a plurality of conduits connecting the elements to the fluid circuitry through which a fluid stream of the fluid sample is conducted; - the functionality of at least two elements of the group of elements of the circuitry is integrated in one integrated microfluidic element , - the one integrated microfluidic element defines a volume element having a volume which is at most one fourth of the minimal working volume of the fluid circuitry , - the integrated microfluidic element integrates the functionality of at least two elements for obtaining information about the properties of the fluid sample, - one element for obtaining information about the properties is an optical measuring element for determining the concentration of the components contained in the fluid sample and - one element for obtaining information about the properties is a measuring element for determining the viscosity of the fluid sample. <EOS>