Procedure
Assemble the instrument. The pieces consist of a Vernier LabQuest 2 data collector/analyzer and a Vernier “SpectraVis Plus” spectrophotometer, or a Vernier colorimeter (gen. 2 or 3). Turn the LabQuest 2 on and wait for the home screen (blue) to appear. Plug the “SpectraVis Plus” into the USB port or the colorimeter into the “Ch. 1” of the LabQuest 2. The home screen should now display a red box, indicating it is ready to use. Verify collection units: if “Abs” is not displayed, tap in the red box, select “change units”, choose “Abs”, and press OK.

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WORKING WITH THE SPECTRA VIS PLUS
Calibrate once before beginning scanning samples, and repeat the following procedure for each sample. Note that when beginning a new scan, the instrument may ask if you wish to save the data from the last scan. Tap “no”.

Calibration: Tap in the red box on LabQuest 2, tap ‘calibrate’ and wait for the lamp to warm up. LabQuest 2 will show ‘ready’ when warm-up completes. Prepare a calibration blank: fill a clean cuvette ¾ full with deionized (DI) water, cap it, and clean it, using a Kimwipe to remove any fingerprints and oil. Insert the cuvette in the sample slot, aligning its smooth sides with the arrow and light symbols. On the LabQuest 2, tap “finish calibration”, then tap “OK” when complete and remove the blank. The instrument is ready to analyze samples.

Sample absorbance: repeat these steps for each sample. Insert a sample cuvette into the instrument after cleaning thoroughly with a Kimwipe, inserting the cuvette in the sample slot by aligning its smooth sides with the arrow and light symbols, then tap the green “start” button at the bottom left of the screen. When the scan is completed, tap “stop”. The screen should contain a spectrum of “Abs vs. wavelength in nm”.
Tap anywhere on the spectrum near the wavelength of interest and use the arrows at the bottom of the screen to hone in on it. The wavelength value and absorbance will both display on the right side of the screen – record them. Do this for each wavelength interest.

WORKING WITH THE COLORIMETER
Calibrate the instrument at each wavelength before analyzing samples from most dilute to most concentrated or lightest to darkest (both models). Available wavelengths are preselected on this instrument and selectable by pressing the left or right arrows on the colorimeter.

Calibration: Calibrate at each wavelength before analyzing samples from most dilute to most concentrated or lightest to darkest (both models). Prepare a calibration blank by filling a clean cuvette ¾ full with de-ionized (DI) water, cap it, and clean it, using a Kimwipe to remove any fingerprints and oil. Insert the cuvette in the sample slot, aligning its smooth sides with the arrow on the colorimeter (gen. 2: up-down; gen. 3: left-right). Tap ‘calibrate’ on the top of the unit. Calibration completes when the flashing red light becomes a steady green and the LabQuest 2 displays 0.000 abs. The instrument is ready to analyze samples.

Sample absorbance: analyze from the most dilute to most concentrated or the lightest-colored to the darkest colored. Arrange the samples from lightest (1) to darkest (n), or from most dilute (1) to most concentrated (n). Analyze in that order. Clean the sample cuvette thoroughly with a Kimwipe to remove fingerprints and oils. Insert it into the instrument, aligning its smooth sides with the arrow on the colorimeter (gen. 2: up-down; gen. 3: left-right). The LabQuest 2 will immediately begin reading the sample absorbance. Record the value when it becomes steady. Repeat for each sample in order of increasing concentration. When all samples have been analyzed, select the next wavelength and repeat the procedure beginning with the calibration.