Sciencemadness Discussion Board

Arsenazo III

careysub - 13-2-2015 at 14:47

This is a bit of a long shot - but is anyone interested in getting together for a group buy of arsenazo III?

What, you may ask, is arsenazo III?

It is a spectrophotometric complexing reagent that makes stable intensely colored (visible spectrum) compounds out of actinide ions, such as Th, U, Np and Am, making microgram amounts visible. It costs a few hundred dollars for 5 grams, if you can source it (I think I can), but the amount needed to trace detection of actinides is tiny.

I have in mind doing actinide trace chemistry with it, you can detect very low levels of the ions using it. I have one of these cheap public lab spectrometer kits, and I am interested to see what level of detection is possible using the two things together.

It could also be used to make microgram quantities of americium and neptunium visible for element collections.

neptunium - 13-2-2015 at 18:21

sounds like fun! but why not invest in a gamma and/or alpha spectrometer instead? it could be used for other radio nucleides and can detect ridiculously small quantities of active element?
The visible part for element display is very seductive though....
does this arsenazo lll have different color for various oxidation states AND element? i`d like to see a chart!

careysub - 13-2-2015 at 18:54

Quote: Originally posted by neptunium  
sounds like fun! but why not invest in a gamma and/or alpha spectrometer instead? it could be used for other radio nucleides and can detect ridiculously small quantities of active element?
The visible part for element display is very seductive though....
does this arsenazo lll have different color for various oxidation states AND element? i`d like to see a chart!


Because the investment in the gamma and/or alpha spectrometer is w-a-a-a-y more money! If money were no object I would just pop for the 5 grams myself.

I'll compile a list of what I have about the complex properties and post in a few days.

Even the guys with unlimited bucks for fancy equipment (national labs) use arsenazo III for doing tests and analyses.

BTW Onyxmet.com has arsenazo I for cheap, as well as xylenol orange both of which have some value for this sort of thing, but arsenazo III is the premier agent for making intensely colored actinide complexes.



[Edited on 14-2-2015 by careysub]

j_sum1 - 14-2-2015 at 02:19

Element colectors might be interested in microgram actinide samples that are already made visible with this stuff.
In other words, don't throw away your samples when you are done. Instead throw them in an ampoule and label with the measurement you just made and provise details of the complexing agent. I can think of much worse ways to deal with your waste. I'd buy some and I don't think I am alone here.

Just out of interest, when you say that arsenazo is expensive, how much is 5g worth?

edit
what colours are the various actinides when complexed?

[Edited on 14-2-2015 by j_sum1]

careysub - 14-2-2015 at 06:26

Quote: Originally posted by j_sum1  


Just out of interest, when you say that arsenazo is expensive, how much is 5g worth?

edit
what colours are the various actinides when complexed?


Sigma lists it for $110 for 5 grams, but you can't buy it directly from them of course. ReagentShop lists is for $275.

It is pink in solution, changing to emerald green in sulfuric acid when complexed. It has a molar absorption coefficient of 10^5 or better.

I intend to experiment with thorium and uranium at first to become familiar with it before moving on to americium. You can get 2 micrograms of neptunium by buying an old Pyrotronics smoke detector from the 1970s. And then there is (eventually) the possibility of isolating protactinium from natural uranium ore.

Arsenazo I (aka Neothorin) is, like I said, cheap from Onyx Metals and I will start working with that. It's molar absorption coefficient is 2x10^4. It makes an orange or orange/red color (changing from red-violet). Less information is available about it since everyone working with actinides uses the more sensitive III.

The acid used affects the color and, like I said, it will be a few days to pull together everything I have about this.

I had not planned to throw out any samples of the rarer actinides, for sure.

[Edited on 14-2-2015 by careysub]

careysub - 16-2-2015 at 14:08

Tom Holm can apparently get 1 g of arsenazo III for $80, which looks like the best bet.

In the procedure for doing Np determination in the "Neptunium Radiochemistry" book in the LANL Library hosted by SM they make up 1 g of arsenazo III into 500 mL of stock solution, and use 2.5 mL of that with 25 mL of Np containing solution for running in the spectrophotometer, with a sensitivity down to about 25 nanogram/mL.

The absortion coefficient of the complex is about 40 times higher than that of potassium permanganate, which can be visually detected at a concentration of 50 micrograms per liter (but in a large sample so that you are viewing through several cm of fluid).

So it looks like <1 mg of arsenazo III should be able to visualize 0.2 micrograms of an actinide in 1 mL of solution. That is the amount of americium in one modern ionization smoke detector.

That gram should go a long way.

gdflp - 16-2-2015 at 14:39

I'm probably going to regret saying this, but couldn't arsenazo III be synthesized? It doesn't look like a terribly complex molecule, the only big issue would be handling the arsenic intermediates. From the looks of it, I would assume that it could be synthesized by arsonating(is that even correct nomenclature?) aniline to form o-aminophenylarsonic acid(probably a minor product due to the sterics of the giant arsenic atom) which could then be coupled with 1,2,7,8-tetrahydroxy-3,6-disulfonaphthalene to yield an impure arsenazo III with various by products. Not saying it would be simple, but is this plausible? In the end, it may not be worth it if you can just by a gram for $80.

[Edited on 2-16-2015 by gdflp]

The Volatile Chemist - 16-2-2015 at 15:06

Hah, doesn't look so simple to me... but I have always loved dye chemistry. How would one go about 'arsonating'?

gdflp - 16-2-2015 at 15:17

Wikipedia states that phenylarsonic acid can be formed by treating a diazonium salt with sodium arsenite in the presence of a copper(II) catalyst. In hind sight, the better way to go about this would be to nitrate acetanilide to form a mixture of p-nitroacetanilide(major product) and o-nitroacetanilide(minor product), isolate the ortho product and hydrolyze it to form o-nitroaniline. This can be treated with sodium nitrite to form the diazonium salt. After adding the AsO3H group, the nitro group could be reduced to an amine using a Sn/HCl reduction.

Boffis - 17-7-2015 at 07:28

This dye and a group of related ones are high on my list of "to do" synths. I have acquired all of the materials and curiously it was the chromotropic acid (1,8-dihydroxy-3,6-naphthalene disulphonic acid di Na salt) that proved most difficult to obtain, though I have now obtained an adiquate supply and it crops up on ebay fairly regularly now. I made a small quantity of o-arsanilic acid some years ago using the route from o-nitroaniline via a modified Barts synthesis. The main problem I encountered was the reduction of the 2-nitrophenylarsonic acid to the arsanilic acid with ferrous sulphate. The ferrous sulphate is converted into brown sludge which was more difficult to filter that I had expected and impossible to wash so the yield was rather low compared to procedure I was following. I don't have my lab notes but I think I have the published papers on my computer. On the issue of the ferric oxide sludge I wondered if it might be possible to use a cleaner reducing agent such and sodium borohydride and just a catalytic amount of iron compound; any thoughts from the experts?

I used the acid to make Arsenazo I because this requires only one M Eqv of arsanilic acid per mole of chromotropic acid were as arsenazo III requires two. I also did some experiments with anthranilic acid first to "prove" the technique. There is a Russian paper that describes the preparation of dozens of similar compounds including a one from diazotized picramic acid. I intend to repeat the preparation of o-arsanilic acid sometime and you have certainly proded me into doing this next time I am home. I fI do I'll post some pics:P

On a related issue there is a dye called Sulphanazo III, it is a reagent for certain M2+ ions (eg Ba) and it is prepared by coupling 2 Meqv of diazotized 2-aminobenzene sulphonic acid with 1 Eqv of chromotropic acid. The problem is that the synthesis of the 2-amino sulphonic acid is complex and I wondered if it would be possible to prepare a similar compound, say a 4-nitro or 4-methyl 2-aminobenzene sulphonic acid using the sulphanilic acid synthesis but replacing the aniline with p-toluidine or 4-nitroaniline (the theory being that when the 4-position is blocked the sulphonic acid group will enter the 2 position instead)? Any thoughts on this?

The Volatile Chemist - 21-7-2015 at 13:18

What is the Russian paper you speak of? If it's in Russian, I'll get a friend to translate at least the interesting parts, if you have a copy.

Boffis - 21-7-2015 at 19:11

Hi Volatile Chemist; the paper that describes the preparation of numerous related derivatives is:

V. I. Kuznetsov and S. B. Savvin, Mitteilungsblatt Chem. Gesellschaft in DDR, Anal. Chem. Sond., 1960, p161.

I don't have a copy of this paper in any form and I couldn't find a digital version on line. Although most of S B Savvin's papers where published in Russian its just possible this one is in German because it was published in an east German journal. Could anyone get a copy of this paper? It would be mega useful.

Two other papers of interest are:
S. B. Savvin, Doklady Akad. Nauk. USSR, 1959, v127, p1231.
V. I. Kuznetsov, Zhur. obshchei Khim., 1950, v20, p807, p816.

These two appear to be specifically about arsenazo III

The most useful article in by S B Savvin is in Talanta (1961), v8 i9, p673; this paper not only describes its use but its preparation and purification, I have an electronic copy somewhere if anyone is interested.

There are numerous other papers, mostly in Russian, concerning similar non-arsonic acid bearing dyes based on chromotropic acid, I have quite a list of references but not with me at present most don't seem to be available electronically. These include sulphanazo III (for Ba2+) and chromotrope 2C (for Be2+) and many others.

The Volatile Chemist - 27-7-2015 at 11:29

Any papers you do have in electronic form I'd be interested in.

Boffis - 31-7-2015 at 13:55

@Volatile Chemist, sorry I hadn't notice you had replied to this thread.

Attached is the paper from Talanta referred to above. It has a detailed prep of arsenazo III and well as its application. Could someone get the Kuznetsov & Savvin paper? I would be well pleased.

Attachment: Analytical uses of arsenazo III Talanta S B Savvin 1961 v8 p673.pdf (556kB)
This file has been downloaded 2003 times

The Volatile Chemist - 2-8-2015 at 15:01

Thanks! Good read.
What color would an americium complex of 'ARSENAZO III' be?

[Edited on 8-2-2015 by The Volatile Chemist]

j_sum1 - 2-8-2015 at 15:24

I see where you are going with that VS. Time to buy a new smoke detector for the hallway.

careysub - 2-8-2015 at 17:27

Quote: Originally posted by The Volatile Chemist  
Thanks! Good read.
What color would an americium complex of 'ARSENAZO III' be?

[Edited on 8-2-2015 by The Volatile Chemist]


According to this:
http://www.sciencedirect.com/science/article/pii/S0003267001...
they measured its absorption at 652 nm, presumably at or near its peak, which would make it red.

With the ability to visually assess the complex at 0.5 micrograms/ml that would be about 2 microcuries per ml (two modern smoke detectors worth). Of course you could use a smaller liquid volume than 1 ml. Devising an optimal visual assessment cell would be an interesting exercise, though must be established art here.

This source:
http://link.springer.com/article/10.1007%2FBF02036502#page-1
states that the color is stable for at least 48 hours. I wonder if it can be made permanently stable.

[Edited on 3-8-2015 by careysub]

The Volatile Chemist - 9-8-2015 at 14:06

Shoot, that's too bad about stability... perhaps an oxygen-less environment would help?
Quote: Originally posted by j_sum1  
I see where you are going with that VS. Time to buy a new smoke detector for the hallway.

It's VC or TVC, thank you very much... ;)
No, of course I'd take the basement one. Our house has two, one in the hallway and one in the basement :)
No, I wouldn't do that. Besides, i have no Arsenazo... :)

careysub - 9-8-2015 at 14:59

Quote: Originally posted by The Volatile Chemist  
Shoot, that's too bad about stability... perhaps an oxygen-less environment would help?


I don't know for a fact that the color complex ever decomposes or fades, references only cite that it is stable for at least n hours (in this case n=48).

Remember the application here is analysis - normally analytical procedures are completed in a work day or two, they may not care if it is stable for a week. Also, the standard of stability for analysis is probably pretty strict - they are trying to make quantitative or semi-quantitative determinations so even slight fading is bad.

j_sum1 - 9-8-2015 at 15:21

Quote: Originally posted by The Volatile Chemist  
Shoot, that's too bad about stability... perhaps an oxygen-less environment would help?

Quote: Originally posted by j_sum1  
I see where you are going with that VS. Time to buy a new smoke detector for the hallway.

It's VC or TVC, thank you very much... ;)
No, of course I'd take the basement one. Our house has two, one in the hallway and one in the basement :)
No, I wouldn't do that. Besides, i have no Arsenazo... :)

Ah yes. TVC. One day my brain will operate properly.
On arsenazo III, I am intrigued. It seems to me to be a really interesting way to display Am and possibly some other elements in the element collection. Right now, the button extracted from the smoke alarm is looking a bit lame for display purposes.

The Volatile Chemist - 12-8-2015 at 08:07

Indeed it would be :)
I have no element collection as of yet, but if I start one, it'd be a while before I got around to purchasing a new smoke alarm solely for its alpha particle source.