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I am a 3rd timer postdoctoral fellow with some experience in molecular biology and biochemistry, but major skills in Zoology and Natural History. I am studying some natural extracts, and isolating compounds.

Some biological samples come in limited amounts (e.g. invertebrate haemolymph), hampering analytical methods that rely on larger amounts. For instance, establishing UV-Vis spectra of extracts is a usual non-destructive method for approaching unknown samples and estimating general parameters, done with a spectrophotometer.

The microvolume-scaled spectrophotometer system popularly known as 'Nanodrop' has been around labs since almost two decades now. Its use has been usually limited to fast purity & concentration estimations for DNA & RNA in molecular biology labs.

I am considering using the nanodrop to estimate parameter of other biological and chemical samples. The manual says most commonly used solvents are compatible with the system. I have however yet found no-one else who has tried using Nanodrop for different applications.

Please, anyone here who has experimented using a Nanodrop system with other biological samples and extracts could comment on the experience?

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The Nanodrop is a generic UV-visible spectrophotometer. According to the manufacturer, the latest model can measure absorbance from 190 to 850 nm. Its dynamic range is also very good: from about 0.1 to about 60 in absorbance. Therefore, as long as you don't use an incompatible solvent, you can measure anything that absorbs in this wavelength range. I use it very often for purified proteins. It also works well for turbid suspensions (like bacterial cultures; reading optical density at 600 nm gives an idea of turbidity).

It is easy to use, and of course the low volume requirement is a big advantage. One drawback is that it won't let you fine tune certain parameters like a "real" spectrophotometer would allow (bandwidth, gain, etc.). But you can definitely get decent spectra for characterization of mixtures and concentration estimation of pure samples.

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  • $\begingroup$ 'you can measure anything that absorbs in this wavelength range' -- Yes, I have been trying out for the first time recently. But have you officially done it? My peers seemed revolted as they state a nanodrop should be used only for DNA/ RNA/ protein standards. They sounded so dogmatic. $\endgroup$ – Scientist Feb 11 '18 at 7:05
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    $\begingroup$ Yes, I have measured absorption of fluorescent dyes that is nowhere near absorption wavelength of proteins or nucleic acids. Using a Nanodrop only for proteins and nucleic acids seems like a lab policy (in my opinion, too strict and not justified), but it is definitely not a technical limitation of the instrument. $\endgroup$ – Guillaume Feb 12 '18 at 15:51
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I used the Nanodrop for the measurement of the absorbance at 600 nm of bacterial cultures, as well as nucleic acid preparations. However, I switched to using another spectrophotometer (Spetrophotometer, Ultrospec 2100 pro, UV/Visible Spectrophotometer, Amersham Biosciences) for my bacterial cultures because I trust it more due to using a cuvette containing 1 ml of bacteria instead of just 1 microlitre of culture.

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  • $\begingroup$ In fact some nanodrop models do have a special pedestal for measuring OD600 of microbial growth. I ought to have mentioned that in my brief intro for the question. My main issue is, as soon as I mentioned to peers I'd be using nanodrop with other biological samples they got revolted, stating 'a nanodrop should be used only for DNA/ RNA/ protein standards'. I was wondering why they sounded so dogmatic about it, and how readers would receive if I employed it otherwise. $\endgroup$ – Scientist Feb 11 '18 at 7:09
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    $\begingroup$ Maybe some people measure their sample and retrieve afterwards and you are contaminating the system. They might be concerned that their sample gets contaminated? $\endgroup$ – charlesdarwin Feb 11 '18 at 13:07
  • $\begingroup$ Perhaps. Nanodrop is naturally unstable, and people may blame anything for a weird result. But if samples are soluble in compatible solvents, I see no logical point, and they really declared they believe it is designed solely for nucleotide analysis (which is not what it says in the manual). $\endgroup$ – Scientist Feb 11 '18 at 14:36

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