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Chemistry LibreTexts

3. Installing a New Capillary

The content of this section is specific to the UV-vis absorbance detector and optical flow cell used with Homebuilt CE system. Please refer to “Section 5: Integrating the Detector” and the parts list provided with the standard operating procedure for Fabricating a Homebuilt CE system for additional information. If using a different detector or flow cell, please consult the respective user’s manuals prior to installing the capillary. The detector should not be on at any time during the installation process.

  1. Remove the flow cell cover from the detector. Next remove the flow cell. Place the flow cell on a clean surface with the optical lens facing up. Be careful to avoid damaging the lens.
  2. Hold the capillary vertically such that the shorter length of polyimide coating is pointing down. Thread the capillary through the first vespel ferrule. The conical end of the ferrule should point towards the detection window.
  3. Slide the capillary into the port located on the top side of the optical flow cell for the UV-visible absorbance detector. The capillary should be seen passing through the central channel of the flow cell.
  4. Thread the screw into the flow cell on the same side as the vespel ferrule. As the screw is finger tightened, adjust the capillary so that the detection window is aligned with the optical lens of the flow cell.
  5. Thread a second ferrule and a second screw onto the opposite end of the capillary. The ferrule should rest inside the port of the flow cell, with its conical end facing the detection window. Finger tighten the second screw.

    Flow Cell (Close-Up)

  6. If the detection window is not in line with the lens of the optical flow cell, it can be adjusted by loosening each screw a half of turn and adjusting the capillary. Once properly adjusted, each screw should be finger tightened such that the capillary does not move under gentle tugging.
  7. Replace the flow cell cover. Ensure that the screws holding the cover to the flow cell are fully tightened. If this cover is not in place or not completely secure, it will interfere with the UV-visible absorbance readings, and could damage the photomultiplier tube.