How to Zero a UV/Vis Spectrometer
Having a proper zero on an ultraviolet-visible (UV-Vis) spectrometer is vital to making accurate measurements. The process is normally very straightforward and uncomplicated if you have past experience with a UV-Vis. "Zeroing" a UV-Vis provides the baseline for the measurements you will take. This is essential with any spectrometer work. In some models of spectrometers, there is dual-beam capability, which allows the spectrometer to zero itself at every point while simultaneously collecting data.
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Things You'll Need
- Two cuvettes of the proper size for your machine (normally standard is 1cm)
- Sample inside the cuvette
- Background sample inside the other cuvette
Instructions
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Press the zero button on the spectrometer or in the software. This is ensure that you machine records zero when no changes are being made inside. This function is similar to "tare" on a balance and serves to negate any light that may be getting to the detector.
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Place your background sample into the sample holder inside the UV-Vis spectrometer. The proper background should include anything in your actual sample that you do not wish to have measured. Performing the background will help to eliminate the extra interference due to the matrix of the sample.
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Scan the background sample in the same manner you plan to scan the actual sample. The spectrometer will be able to record the results from the background and subtract the background's signal from the actual sample signal.
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Save the background scan. Normally the spectrometer will save this for you and auto-subtract. However, some models will require you to load these results into a special place for backgrounds. Consult the spectrometer's manual to be sure.
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Remove the background sample from the UV-Vis sample holder. You are now ready to perform a scan of your actual sample. For best results, it is ideal to use the same cuvette that your background sample was in. This is not a necessity, and if your background sample is complex you may wish to use different cuvettes. Just make sure they are the same size!
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Tips & Warnings
Check to see if your spectrometer has a tutorial video or a sample walk-through in the instruction manual. This will often be the best place for specific instructions about your spectrometer.
