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Use a clean cuvet that is free of chips and cracks (though a cuvet with a chip near the top of the cuvet could be used).
Rinse the cuvet several times with a small amount of sample. Fill the cuvet at least half full. Wipe the outside of the cuvet with a laboratory tissue to remove fingerprints or small amounts of the liquid.
Why is important to to wipe the outside of the cuvet?
Answer
If not removed, fingerprints and small amounts of liquid may cause inaccurate and inconsistent readings of a sample. Additionally, small amounts of liquid would be transferred to the spectrometer potentially damaging the spectrometer. Check your sample for air bubbles. If there are air bubbles in the sample, gently tap the cuvet to displace the bubbles. If the bubbles remain, thoroughly clean the cuvet, rinse it with sample solution, and refill it. Don't forget to re-wipe the outside of the cuvet with a laboratory tissue.
Insert the cuvet into the sample compartment. Align an index mark near the top of the cuvet with a mark on the sample compartment. Align the cuvet the same way for each reading. Close the sample compartment lid.
Why should you fill the cuvet half full and check for air bubbles?
Answer
If air bubbles are present in the cuvet, the light beam will pass through air instead of your sample solution thus the absorbance will be incorrect. |
