Sub Micro Cell, low head space. The cell and liquid-tight stopper are specially designed so the volume of air above the sample is reduced by >95% compared with normal sub-micro cells. This reduces evaporation loss of samples such as DANN to a minimum. Round internal solid black top closed by a specially profiled PTFE stopper. To avoid possible meniscus errors, it may be necessary to increase the nominal sample fill volume by at least 20%. Filling and emptying with a pipette is recommended.