Hitachi U-2000 Spectrophotometer:

The U-2000 (picture) is a programmable spectrophotometer with the "sipper" option attached. It is currently programmed for lignin, phosphatase, oxidase and dextrose. Because it is jointly owned by both the Vitousek and Mooney labs, you should check both labs to make sure it is available when you need it. Note that Vitousek lab keys do not give access to the Mooney lab, therefore you will need to make special arrangements for any after hours use.

Things to bring with you;

• samples and blank solution
• a waste container
• the quartz reference cell
• a means to record the data

Start-up;

Remove the dust cover.
Place the waste line into your waste container.
Turn the power on; the switch is located on the front lower left side. The instrument will go through several self checks and make a few clunking noises. When finished, a menu will be displayed with a cursor flashing at "SELECT OPTION". For a programmed analysis press 6 and then enter. This will bring up the test menu. Press 1 and enter to load a test. It then prompts you to enter a value from 1-20. If doing lignin, for example, press 1 and enter. The instrument will then load the proper program and adjust to the needed wavelength. It's a good idea to let it warm-up for 15-20 minutes. During this time, fill the reference cell about 2/3 full with your "blank" solution and insert it with cap into the cell chamber within the sipper.

Running your samples;

• Release the clamp on the waste line.
• Pull back the pump tube tensioning plate until you hear a click and the release button pops up.
• Slide the sipper door closed.
• Insert the sipper tube into some blank solution and run 3 or 4 sample cycles by pressing the large stainless steel actuator.
• Press AUTO ZERO on the keypad. Resample and zero until you are satisfied with a baseline value.
• Insert the sipper tube into your first sample and press the actuator tab. Always consider the first sip to be an adjustment and don't use the reading. Also, between sips, insure that the sipper tube remains within your sample so as not to introduce an air bubble.
• Sip once more and note the reading.
• Sip again and note the reading. If it is unchanged, record it and move on to the next sample. If the reading has changed, sip until it stabilizes. Normally three sips is enough, but if a previous sample was very different, additional sips may be required.
• When all samples have been run, or intermittently for a large batch, run a blank again to check drift.

Shutting down;

• Place the sipper tube into a container of DIH2O and WASH at least 100ml through the system.
• Replace the clamp on the waste line leaving water in the system.
• Release the tension on the pump tube by pulling back the tension plate and pressing the release button.
• Remove the reference cell.
• Close the sipper door.
• Turn off power.
• Replace the dust cover.
• Remove your waste container.

If you are completely done with your samples and nobody else is in line to use the spectrophotometer, an additional washing step is required. After rinsing with water, insert the sipper tube into the bottle of cleaning solution (kept just to the left of the instrument) and run three sample cycles. Clamp the waste line and allow the solution to soak the sample cell overnight. The following day, rinse the system out with water.