The Model 7520 uses a small hole drilled in a flat rotor as an internal sample chamber for precise sample injection. The rotor, which is sandwiched between two stators, is available in 0.2, 0.5, and 1µL volumes; 0.5µL is standard. The 7520 requires the complete-filling method of loading the internal sample chamber. Excess sample is required to completely flush mobile phase from the chamber.

      The schematic diagram shows the rotor in the LOAD position. The sample chamber is loaded by inserting a syringe needle into the built-in needle port. The space between the needle tip and rotor surface contains only 0.3¼L so there is very little sample wastage. Rotating the handle to the INJECT position places the sample chamber into the mobile phase stream.

      The outlet stator passage is 0.13mm (.005 inch) diameter. A column connecting tube of matching I.D. is supplied installed in the outlet port. The 1/16 inch O.D., 5cm long tube makes it easy to connect microbore columns of various designs.