TECHNOLOGY FOCUS - MECHANICAL ENGINEERING - Preferred Parameters: In the device, the distance between (i) the aqueous flow channel inlet, and (ii) the end of the restricted opening that is furthest away from the inlet, is smaller than the length of an aqueous sample droplet. Preferred Components: The oil removal device comprises one or more pillar elements at the opening of the oil outlet channel. The device is made from a material which is hydrophobic. The oil outlet channel is located in a side wall of the sample delivery channel. The aqueous flow channel inlet is located at the end of the sample delivery channel. Preferred System: In the system, the conduit is of a sufficient length to retain or store all of the oil-separated sample droplets. The device is provided in two separate parts connectable by the conduit. The first and second separation apparatus are each an apparatus for resolving a set of components from a mixture. The first and second separation apparatus each carry out a different separation technique. Preferred Method: In transferring the aqueous analyte solution between the first separation apparatus and the second separation apparatus, the oil in the conduit does not enter the aqueous flow channel, due to surface tension effects at the aqueous flow channel inlet. The conduit is a channel or tubing. The conduit is a length of tubing able to receive all of the oil encapsulated analyte droplets. The oil encapsulated analyte droplets may be stored in the tubing. The oil encapsulated analyte droplets are transferred through the conduit to the second separation apparatus. The oil has a surface tension to the device material that is less than the surface tension between water and the device material. The oil is electrically non-conductive. The pressure is applied to drive the droplets and the oil flow downstream to the aqueous flow channel inlet, and suction means are applied to the oil outlet channel to aspirate oil from the oil outlet. The first and second separating apparatus are different separation techniques. The analyte solution comprises a set of molecules or macromolecules. The analyte solution comprises a set of molecules or macromolecules, selected from any of the following: protein, protein fragment, peptide, nucleic acid, DNA, RNA, amino acid, organic molecules, inorganic molecules and cells. Each separation apparatus is independently selected from: High Pressure Liquid Chromatography, Liquid Chromatography, Isoelectric Focusing, Capillary Electrophoresis, Capillary Gel Electrophoresis, Isotachophoresis, and micellar electrokinetic chromatography. The method further comprises the use of detection means for either one or both of the first and second separation means. The detection means are independently selected from: UV detection, fluorescence, phosphorescence, staining, radioactivity, refractive index detection, and vibrational spectroscopy. Moreover, any one or more of the following agents is added in an aqueous solution via an additive channel connected to the conduit: a fluorescent agent or label, a radioactive label, a dye, a buffer additive and an affinity ligand.