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I'm trying to design an experiment to detect nM quantities of Copper(I) Oxide in fish blood. Are there any specific tests for Copper(I) Oxide that can be used to detect trace quantities(~nM)? Any non-destructive tests such as using optical methods would be preferable.For purposes of designing the experiment, let's assume the particles are nano-sized and dispersed in blood.

user1155386
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    Add some context to your analytical problem. What is the sample? Cu(I) is not stable in water with respected to oxidation. Cu(I) oxide is a solid which does not dissolve in water as well. Do you have a solid dispersed in water? Are you specifically interested in only one species Cu(I)? – AChem May 05 '19 at 17:22
  • I posted the original question thinking I could simplify the problem by calling it a water dispersion, but I have added what I am trying to do in more detail. – user1155386 May 05 '19 at 17:27
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    Nano-sized is good, because you can first filter out any blood cells, platelets, etc. Greatly simplyfies your problem. Why Cu(I) nanoparticles, specifically? – Karl May 05 '19 at 18:38
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    @Karl Some farmers use co-culture, which means they culture fish in the water clogged in paddy fields. Cuprous oxide is a cheap and effective fungicide they often use with paddy. For my project I am trying to assess how much of this enters the fish's blood stream. I guess it is tiny, but I wanna validate that. – user1155386 May 05 '19 at 19:17

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The main analytical problem in your case of detecting Cu(I) oxide in blood is that you do not know the fate of the particles once they enter blood stream. As I said earlier, Cu(I) is thermodynamically not stable in any aqueous system. It oxidizes to Cu(II), which is water soluble. The non-destructive technique to detect species is X-ray photoelectron spectroscopy, but its detection limit is very poor. It may take a day to collect weak signals from such a low concentration of Cu(I) oxide. The sample has to be bone-dry as well! This is a species specific analysis, i.e. one can distinguish oxidation states of metals by deconvolution.

A practical suggestion is that you do a control test, i.e. measure copper levels before treatment in blood. As a result, all copper originates from your copper (I) oxide dispersion. You would not know the specific species of copper but you will get the total content. For that one can use common techniques such as graphite furnace atomic absorption analysis (only a few microliter of sample is required).

AChem
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  • I am having trouble understanding Cu(I) Oxide's thermodynamically instability in aqueous system: don't tests like Benedict's reaction produce copper(I) oxide that precipitate out unoxidized? – user1155386 May 05 '19 at 18:05
  • Yes, but if you let it sit for sometime, it will be oxidized to Cu(II). – AChem May 05 '19 at 18:31
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    There will be problem with AAS, that supposed cuprous oxide would be far below the physiological copper content. The question "why cuprous oxide ?" remains. – Poutnik May 05 '19 at 18:40
  • @Poutnik, Karl had the same question, so I provided more context to my problem in the comments – user1155386 May 05 '19 at 19:18