SPEC-20 VISIBLE SPECTROPHOTOMETERS

Prepare the Instrument 1. Turn on the instrument using the zero control on the front of the meter. Allow the instrument to warm up for at least one-half hour.   2. Use the wavelength control on top of the meter to set the instrument to the desired wavelength. Calibrate the Instrument 1. With nothing in the closed sample compartment, use the zero control to obtain a 0 %T reading. Position your eye so that the meter needle is directly above its reflec-tion in the mirror scale. 2. Rinse a small test tube (cuvette) with a blank solution or deionized water. Fill the cuvette about one-half full with the blank solution, eliminate any air bubbles, and gently dry the outside with a tissue. 3. Place the cuvette into the sample compartment, rotating the cuvette so that the alignment mark on the sample compartment lines up with the line on the cuvette. Verify that the cuvette is inserted to its maximum depth. 4. Close the sample compartment, and use the full-scale control on the front of the meter to obtain a I 00 %T reading. 5. Remove the cuvette and repeat step 3 to re-zero the instrument. Then repeat steps 4 and 5 to reset the full-scale adjustment. Remove the cuvette. Use the Instrument 1. Rinse and half fill the cuvette with the solution to be measured. 2. Insert the cuvette as before, close the sample compartment, and quickly obtain the %T reading. Remove the cuvette 3. Repeat the steps as before for your remaining solutions to be measured. Remove the cuvette when finished. 4. If the instrument will not be used within one to two hours, turn if off. Otherwise, turn the zero set control fully counterclockwise without turning off the instrument. 5. Wash and rinse all the cuvette. Dry them in an inverted position.

Spectronic-21 SPECTROPHOTOMETERS The Spectronic 21 differs from the Spectronic 20 in that it utilizes solid-state electronics and uses smaller cuvette. Further, it lacks a zero control because it zeroes automatically. It may also have a digital display instead of an analog display. The Spectronic-21 provides improved performance over a wider wavelength range.
Prepare the Instrument 1. Turn on the instrument with the power switch on the right-hand side of the lower front panel. Allow the instrument to warm up for 15 - 30 minutes. 2. Select the wavelength with the wavelength selector on top of the meter. Calibrate the Instrument 1. Rinse a cuvette with a small amount of blank solution or deionized water. Fill the cuvette to its fill-level mark, or at least to a 4 cm height. Gently wipe the outside of the cuvette with a tissue. 2. Open the sample compartment and insert the cuvette containing the blank. Rotate the cuvette until the alignment mark on the sample compartment aligns with the mark on the cuvette. 3. Close the sample compartment. Adjust the full-scale control on the left of the lower front panel to obtain a 100 %T reading. Remove the cuvette. Use the Instrument 1. Rinse and fill the cuvette with the solution to be measured. Place it in the sample compartment as before. 2. Close the sample compartment and obtain the %T reading. 3. Turn off the power switch if the instrument will not be used again within one hour. 4. Wash and rinse all cuvette and dry in an inverted position.

Pictorial Tutorial

 

YouTube Video

1. University of Toronto Tutorial: https://www.youtube.com/watch?v=Fqw1ULEOkwg
2. Professor Liu: How to use the Spectrophotometer: https://www.youtube.com/watch?v=EvDwmgSbnnk
3. Journal of Chemical Education Instrument Page: https://www.chemedx.org/JCESoft/jcesoftSubscriber/ChemPagesLab/modules/spec20/spec20desc.htm
4. SSpectrometer Breakdown: https://www.youtube.com/watch?v=xuwHsSJ5RZ0

 

 

Back to Top

Back to Course Information

Back to FOG Home page