The invention relates to the field of microfluidic detection and analyses. Described herein are methods and devices for the separation, detection and measurement of molecules in liquid samples. Certain aspects of the invention concerns the separation of analyfe(s) of interest based on the combined use of: (i) membrane separation, (ii) an electric field and/or a magnetic field; and (iii) capillary action and/or gravity. Envisioned applications include separation, detection and/or measurement of analytes in blood samples, food samples and environmental samples. One particular example is a portable biosensor for the detection and measurement of histamine and diamine oxidase (DOA) in a drop of blood.
