Using the Spectrovis Sensor with a Labquest Interface

Using the SpectroVis sensor with a LabQuest interface

Making Connections: Plug in the LabQuest AC Adapter to the nearest outlet. Connect its powercord to the LabQuest jack on the left side of the unit labeled Turn on the LabQuest by pressing firmly and holding the power button at the upper left of the screen. Wait for the unit to power up. Connect the USB cable between the SpectroVis (right end) and the LabQuest (USB port at top under the power-on button). When the LabQuest is ready for use, it should show USB: Abs and Mode: Full Spectrum

Calibration: Use the stylus to tap Sensors  Calibrate  USB: Spectrometer Wait for the lamp warmup time.

Insert your blank (2.75 mL dH2O) cuvette (clear sides facing right left, ridged sides facing frontback). This is important, so check it (clear sides facing white ▷ and, ridged sides facing green and purple) Tap Finish Calibration Tap OK

Selecting a Wavelength: Insert a cuvette with a trial reaction sample that has been running for some time. Tap green ▶ (lower left corner of screen) After the full spectrum appears, tap red  After the spectrum is auto-scaled, observe it. Tap a part of the curve where you want to measure absorbance (it will be a place with a peak or a shoulder, not a sloping area). Since the tannins are reddish, the wavelength at Amax will likely be in the blue part of the spectrum (400-450 nm).

Changing to Timed Data Collection: Tap on the meter icon (upper left corner of screen) Tap Mode: In the dialog box, tap Mode: dropdown  and tap to select Time Based Tap in the Length: text area. A keyboard should popup. Tap  to backspace the 200 and enter 90 instead. Tap OK Tap Discard for the spectrum data Continue (over) Observing an Enzyme-Catalyzed Reaction: Pipette a fresh reaction mixture into a cuvette except for the potato homogenate. The potato homogenate is added LAST, and only when you are ready to start the reaction. When the homogenate is added, one lab partner should tap the green ▶ to start the timing, while the other partner immediately caps the cuvette, shakes the completed mixture thoroughly, and inserts the cuvette quickly and correctly into the SpectroVis (clear sides left right). Data will be collected and appear on the graph. When the 90 seconds expire, or you hit red , the Abs vs Time graph is auto-scaled.

Analyzing the Results: Tap Analyze then Tap Tangent (at checkbox) Tap a place on the curve where you believe the slope should be measured (not in the lag or plateau ranges, but in the initial linear portion of the curve). You can tap elsewhere until you find that “right place” where the tangent line drawn by the LabQuest gives a good estimate of the overall slope. Tap Slope: to observe an unrounded value for A/sec reported for that tangent line! Record the Slope: Must have 3 non-zero digits (0.00…xyz)

Later, when prompted, Tap Discard the data from this reaction to go on to the next one.

Preparing for the Next Reaction: One partner should decant the old reaction mixture to the waste receptacle. Then use a thorough distilled water rinse from a wash bottle to clean out the cuvette. After shaking out the distilled water, the cuvette can be used again. Be sure to handle the cuvette by the ridged sides only. Rinse thoroughly and dry the cap too. The other partners can be setting up the next reaction mixture. Go back to the top of this page! Again, you can tap Discard for the old data when prompted in starting the new reaction’s data collection.

Finishing Up For The Day: Power Down the LabQuest by pressing firmly and holding down the power button at the upper-left (has a blue halo around it) for a second or two. When the screen is dark, remove the AC adapter cord, and unplug it by pulling on the plug body. Do not pull on the wire itself! Disconnect the USB cable from the LabQuest and the SpectroVis. Place the Power Adapter under the cardboard insert in the SpectroVis carton. Place the Spectrovis in the niche above the cardboard insert. Close the carton. Remove any cuvette and place the SpectroVis and its USB cable in the SpectroVis carton. Decant all waste reaction mixtures to the designated container. Rinse and shake dry all cuvettes and caps and place in the designated area. Discard all pipettes to the designated area. Discard all KimWipes to the Trash. Cap all stock solutions and return them to the designated area (the lab cart?)