The MULTIVAP blowdown evaporator is ideal for concentrating large batches of samples, and can be used in numerous sample preparation methodologies. These instruments contain a rectangular gas distribution system mounted on a frame and dual post assembly. The manifold delivers nitrogen gas to the needles or glass pipettes, which direct the gas onto the sample's surface. This method results in rapid solvent evaporation and sample concentration. In order to conserve nitrogen gas, the manifold has toggle switches which allow gas flow to individual rows to be shut off when evaporating batches at less than full capacity.