Operating Instructions for the Bausch & Lomb Spectronic 20D+
(Revised 02/09/1999)

1. Sample compartment 5. Decrease 9. Transmittance/Absorbance control
2. Digital readout 6. Increase 10. Power switch/Zero control
3. Mode indicators 7. Print 11. Filter level
4. Mode selection 8. Wavelength control

Operating Instructions

  1. Turn on the instrument by turning the Power Switch (10) clockwise. Allow 15 minutes for the instrument to warm up.
  2. Set the desired wavelength with the Wavelength control knob (8).
  3. Set the filter lever to the appropriate position for the selected wavelength.
  4. Adjust the display to 0% Transmittance with the Zero control (10). Make sure the sample compartment is empty and the cover is closed. This is zeroing the meter.
  5. Set the display mode to TRANSMITTANCE or ABSORBANCE by pressing the MODE control key (4) until the appropriate LED is lit.
  6. Fill a clean cuvette with the appropriate blank solution and wipe the tube with lens paper to remove liquid droplets, fingerprints and dust.
  7. Place the cuvette in the sample compartment and align the guide mark on the cuvette with the guide mark at the front of the sample compartment. Press the tube firmly into the sample compartment and close the cover.
  8. Adjust the display to 100% Transmittance or 0.0 Absorbance with the Transmittance/Absorbance control (9).
  9. Remove the blank cuvette from the sample compartment.
  10. Wipe the cuvettes containing the test solutions and place them in the sample compartment.
  11. Read the appropriate value (% Transmittance or Absorbance) from the display.
  1. Steps 2-9 must be repeated whenever the wavelength is changed.
  2. Check often to be certain that the meter needle reads 0 on the % Transmittance scale with the sample compartment is empty and the lid is closed.
  3. Check often to be certain that the meter needle reads 100% Transmittance when the blank cuvette is in the sample compartment with the lid closed.
  4. Use a matched set of cuvettes. Do not mix cuvettes of different sizes or designs.