Question 1

In the Varioskan LUX Multimode Microplate Reader, how is running a TRF spectrum by setting excitation at 335 nm and using emission range different from running a filter-based TRF assay? Why does SkanIT Software have the TRF spectrum option?

Accepted Answer

The TRF spectrum option is useful for spectral analysis, assay and label development, and optimization purpose. For example, when a new TRF chelate label is developed, TRF spectrum measurement can be used to analyze the spectra when a lot of label is loaded in the well.

When the TRF spectrum option is used, the sensitivity is not sufficient for actual TRF assays as the instrument sensitivity decreases by about 200-fold. Hence, the TRF spectrum option should not be used for normal TRF assay applications. For optimal results, the TRF spectrum option should be used for TRF spectral scanning but not for running actual TRF assays. Actual TRF assays must be performed using filter-based TRF optics in the LAT module.

If the Varioskan unit does not have TRF optics in the LAT module, TRF spectral scanning cannot be performed. In this case, TRF spectral scanning can only be performed using TRF-based filters.

Find additional tips, troubleshooting help, and resources within our Cell Analysis Support Center.

Question 2

How to remove a stuck microplate from the Varioskan LUX Multimode Microplate Reader?

Accepted Answer

Power off the Varioskan LUX instrument, open the sliding door, and then press both springs outward (1) to unlock the bottom of the front panel. Tilt the bottom of the panel outwards slightly and lift up to remove.

Look inside the instrument to locate the tray (3). Gently slide the tray to the left and then towards you to access the plate. Check for jams and make sure that the correct holder is installed. When finished, push the tray back into the instrument (exact position doesn’t matter as long as it is completely inside) and reinstall the front panel.

Note: Remove the bottom front cover on the instrument, in order to access the plate carrier, and manually pull out the plate. Do not attempt to grab the plate back through the plate door, otherwise it can cause alignment issues that will require a repair.

Find additional tips, troubleshooting help, and resources within our Cell Analysis Support Center.

Question 3

Can relative fluorescence units (RFUs) be compared between two different plate readers?

Accepted Answer

Relative fluorescence units (RFUs) cannot be compared between two different microplate readers. RFU values are arbitrary and dimensionless, meaning that the actual numbers don't have a specific physical meaning, but the relative values are used for comparison. The critical measurement is the ratio of signal to background.

Whether the signal is low or high is 100% dependent on the baseline, i.e., if the sample signal is 2 and the baseline is 1, then it is a low signal but if the sample signal is 2 and the baseline is 0.01, then it is a very high signal. Instruments that typically give sample signals in the tens of thousands RFUs also typically have baseline RFUs somewhere in the tens or hundreds. For example, the Varioskan Microplate Reader is designed such that the baseline is kept below 0.1 RFU.

Question 4

How can I move the Varioskan LUX Multimode Microplate Reader from one place to another?

Accepted Answer

We recommend transporting the Varioskan LUX Multimode Microplate Reader in the original packaging it was delivered in, with proper padding in the box, and after securing the tray holder transport lock on the instrument. See page 84 of the user manual for instructions to refit the transport lock of the tray holder.

Note: We also offer a service to move the instrument. Please reach out to serviceproducts@thermofisher.com.

Find additional tips, troubleshooting help, and resources within our Cell Analysis Support Center.

Question 5

Which is the best DNA or RNA quantification instrument?

Accepted Answer

All of the DNA instruments offered by Thermo Fisher Scientific are of excellent quality. To find the right instrument to quantify DNA or RNA in your lab, explore the detailed comparison of UV-Vis spectrophotometers and fluorometers. Things like sensitivity, throughput and budget may be initial considerations when selecting a DNA quantification instrument. You may also consider whether you need target specificity, sample purity information, RNA quality information, or broad dynamic range.

Find additional tips, troubleshooting help, and resources within our Nucleic Acid Quantification Support Center.

Question 6

What is the difference between UV and fluorescence DNA quantification? Which DNA quantification technology should I choose?

Accepted Answer

UV and fluorescence technologies work differently to quantify DNA. UV quantification relies on the intrinsic absorptivity of DNA and RNA molecules, while fluorescence quantification uses dyes that specifically bind to your molecule of choice. With UV technology, quantification isn't as sensitive, but it has a broader dynamic range and also gives data about sample purity‒plus it is faster because there is no reagent prep. With fluorescence technology you get higher sensitivity and molecule-specific data, but it has lower dynamic range and reagent prep is required. The technology you need will depend on what features are important for your lab and experimentation.

Find additional tips, troubleshooting help, and resources within our Nucleic Acid Quantification Support Center.

Varioskan™ LUX Multimode Microplate Reader, luminescence, time-resolved fluorescence, AlphaScreen, top and bottom, no dispenser - FAQs