looking for oil-soluble fluorescence dye for silicon oil in microfluidic research

[Yi-Kuen Lee]

Dear Chemistry Experts,

I have a little question about the oil-soluable fluorescence dye for
silicone oil used in one of microfluidics reseach. Before I also worked on
water based solution, I used Rhodamine B dye or FITC. But these two don't
work. I have searched some websites as follows:
http://www.taoka-chem.co.jp/dyes/e_dyes.html
http://www.riskreactor.com/UV_Products/Fluorescent_Order_List.htm
http://www.riskreactor.com/Data_Sheets/IFKYR_13_Green_Yellow_Fluorescent_Vis
ible_Oil_Tracer_Petroleum.htm
http://www.ndt-ed.org/EducationResources/CommunityCollege/PenetrantTest/PTMa
terials/ptmaterials.htm

I am not good at chemistry at all. Any suggestion will be greatly
appreciated!

Regards

YK

[Mark Thorson]

Yi-Kuen Lee wrote:

> I have a little question about the oil-soluable fluorescence dye for
> silicone oil used in one of microfluidics reseach. Before I also worked on
> water based solution, I used Rhodamine B dye or FITC. But these two don't
> work. I have searched some websites as follows:

But why didn't they work??? What was the problem?
Was the problem measuring rhodamine against background
fluorescence? If so, you could try rhodamine-123, which
has two absorption bands and two (corresponding) emission
bands. That should allow you to reject any noise from
other fluorophores.

[Yi-Kuen Lee]

"Mark Thorson" <nos...@sonic.net> wrote in message
news:408B39AC...@sonic.net...

The dye molecules I used can't uniformly distribute in the silicone oil.
They will form some cluster.

[Mark Thorson]

Yi-Kuen Lee wrote:

> The dye molecules I used can't uniformly distribute in the silicone oil.
> They will form some cluster.

Rhodamine B has a carboxylic acid group, and
silicone oil is intensely hydrophobic. A molecule
that lacks an acid group is probably a better choice.
Tetramethylrosamine might be a suitable fluorescent
dye, without straying too far from a rhodamine-like
core structure.

[Eric Stein]

Sources vary on whether Rhodamine B has a true carboxylic acid group. My
CRC handbook (2003-2004 edition) shows the carboxylic acid group's hydrogen
as having been removed and the oxygen bonded back into the molecule. Most
sources on the internet (search google for "rhodamine b") agree with you
though. I wonder why my CRC handbook has a different structure.
~Eric

"Yi-Kuen Lee" <mey...@ust.hk> wrote in message news:<c6flgo$aht$1...@news.ust.hk>...

[Mark Thorson]

Eric Stein wrote:

> Sources vary on whether Rhodamine B has a true carboxylic acid group. My
> CRC handbook (2003-2004 edition) shows the carboxylic acid group's hydrogen
> as having been removed and the oxygen bonded back into the molecule. Most
> sources on the internet (search google for "rhodamine b") agree with you
> though. I wonder why my CRC handbook has a different structure.

I'm not sure what you mean by "bonded back into
the molecule", but that sounds like an attempt to
depict a zwitterion, which rhodamine B will become
in solution. That's just trying to convey a little more
information, which the other drawings didn't bother
with. Unlike IUPAC naming, I don't think there is
a formal standard for drawing molecules. I know
it always looks upside-down to me when people
put the anthracene-derived moiety of the rhodamines
on the bottom instead of the top. And if there's
a side-group on the bottom ring (like the carboxylate
group in rhodamine B), I want that to be on the right,
not the left.

[Art Ickles]

> > Sources vary on whether Rhodamine B has a true carboxylic
> > acid group. My CRC handbook (2003-2004 edition) shows the
> > carboxylic acid group's hydrogen as having been removed and
> > the oxygen bonded back into the molecule.

-- snip -- snip -- snip --

> I'm not sure what you mean by "bonded back into
> the molecule", but that sounds like an attempt to
> depict a zwitterion, which rhodamine B will become
> in solution.

When the carboxylate spiro-lactonizes onto the middle ring,
it breaks up the chromophore and cancels the charge on the
diethyliminum group. In this state, there is almost zero
fluorescence. Use monospaced font for ASCII art:

CO2(-)
|
Et2N(+)=Ar-Ar-Ar-NEt2 <=====>
(The Et2N(+)=Ar is not actually an aromatic Ar in this form)

--CO
\ O
\/
Et2N-Ar-Ar-Ar-NEt2

I'd suggest picking a neutral, greasy flurophore OR to attach
a big greasy (silicone) tail to a Rhodamine-CNO or Rhodamine-CNS
to make it more soluble. You still might get micelles, so I'd
look for a small neutral, first.

One of the best sources of fluorophore info AND supplies is
Molecular Probes, www.probes.com . They are mostly bio oriented
but their on-line handbook is excellent. Maybe there's an
equally good company for non-bio fluorophores.

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[Eric Stein]

I'm not sure what's up with it either. I scanned it just now and uploaded it to
here: http://www.parabolagames.com/chem/images/data/rhodamine_b.gif (for
those who don't know, this is from the CRC handbook 2003-2004 edition).
Check it out and tell me what you think.
~Eric

Mark Thorson <nos...@sonic.net> wrote in message news:<408BF9DB...@sonic.net>...

[Larry Smith]

We looked at one called, I believe, Brilliant Yellow at one time for
use
as an oil soluble tracer.
Might be worth a glance.

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[Larry Smith]

[seli...@gmail.com]

Hi
Fluorescein dissolves in oil. I also work on microfluidics and try to avoid dyes that dissolve in oil and fluorescein does not work for me :)
Selis Onel