Filtering method suitable for isolating and/or quantifying, from a sample, at least one substance to be investigated

A filtering method for isolating and/or quantifying, from a sample, a substance to be investigated, the method comprising:

• providing a filter module, including:
• a housing having a first opening forming the sample inlet and a second opening forming a sample outlet;
• and
• a filter covering the second opening, wherein the filter is designed to hold back a first portion of the sample and to allow a second portion of the sample to pass through;
• introducing via the sample inlet a first quantity of the sample into the filter module;
• conducting the sample from the sample inlet through the filter and the sample outlet by applying a pressure difference between a side of the filter facing the sample inlet and a side of the filter facing away from the sample inlet, wherein the second portion of the sample leaves the filter module through the sample outlet as a filtrate;
• detecting while the sample is being conducted from the sample inlet through the filter to the sample outlet a series of temporally sequentially recorded measurement values of a measurement variable which represents the pressure difference and/or a volumetric flow through the filter;
• comparing the measurement values to a predefined reference value of the measurement variable;
• and
• ending the filtering method when successively detected measurement values of the measurement variable, over a predefined timespan, are equal to the reference value and/or lie within a predefined range of values around the reference value.

A device for filtering a sample for isolating and/or quantifying a substance to be investigated, the device comprising:

• a filter module, including:
• a housing having a first opening forming a sample inlet;
• a filter;
• and
• a second opening that is covered by the filter and forms a sample outlet,
• wherein the filter is designed to hold back a first portion of the sample and to allow a second portion of the sample to pass through;
• and
• a control apparatus, including:
• a pressure control device,
• wherein the pressure control device is configured to generate a pressure difference between a side of the filter facing the sample inlet and a side of the filter facing away from the sample inlet,
• wherein the control apparatus is configured to detect measurement values of a measurement variable which represents the pressure difference and/or a volumetric flow through the filter, and
• wherein the control apparatus is further configured to compare a series of temporally sequentially detected measurement values of the measurement variable with a predefined reference value and to determine if successively detected measurement values of the measurement variable, over a predefined timespan, are equal to the reference value and/or lie within a predefined range of values around the reference value.