[xchcui]

Hello.

Is there a simple way or simple test in order to identify if the silver brazing rod contains cadmium or not?
I have few silver brazing rod coated with light blue flux,but without any details on them.

Thanks in advance.

[billnotgatez]

None of the MSDS that I looked at mentioned Cadmium.

[xchcui]

Hi billnotgatez.
The silver brazing rod can be sold with cadmium and without cadmium.How can i confirm with simple test or,maybe, with complicate test at home,that the brazing rod contains cadmium or not?
The msds that you looked,probably,refered to cadmium free silver rod,but searching in msds is not the issue.
How to test it or confirm it at home is my interest.
Thanks.

[billnotgatez]

I did GOOGLE on

how do cadmium test kit work

and got lots of hits
here is one
http://www.home-health-chemistry.com/Cadmium-Detection.html

[billnotgatez]

I might be tempted to do a flame test
It is not definitive but could give you some food for thought.

http://en.wikipedia.org/wiki/Flame_test

I also looked at this page which might help as well

http://en.wikipedia.org/wiki/Qualitative_inorganic_analysis

[xchcui]

The cadmium test kit is good solution but too expensive and i try to find a way to do it with household chemical/detergents.
I did a deep google before posting my question,but it turn out that i needed to use the words"how to TEST..?"as you did.
It gave me alot of good results,indeed.
At one of the sites i found exactly the same question and someone suggested to do a flame test:

Long ago in A-level chemistry learning qualitative analysis the test for cadmium was to look at the colour of a bunsen flame in which one held a little loop of wire with a drop of the salt on it. You could dissolve a bit of an unknown metal in some dilute acid. Bunsen had to be adjusted for a colourless flame first. IIRC cadmium gives a scarlet red flame. Our enlightened teacher encouraged us to set fire to small pieces of the metal on a gauze over a bunsen - lovely colour intense red flame. I don't think many of my chemistry classmates succumbed to anything nasty.
 
Anyway there's your answer. Rub a little acid (vinegar would probably do the trick) on the plating, then use the end of a bit of clean copper wire to pick up a little of the liquid and see if you get a red flame (before the copper gets too hot and gives you a green one).

http://www.model-engineer.co.uk/forums/postings.asp?th=61489&p=2

What are you saying?can that method(as he showed) work with checking the silver brazing rod?

[billnotgatez]

A problem with the flame test is that other elements might mask the color.

The Qualitative_inorganic_analysis link may have a solution as well.

[xchcui]

Most of the silver brazing rod is silver+copper+zinc.
Sometimes it has also low percent of tin or/and silicone.
The silver,zinc and the silicone don't give any color at flame test(as much as understood from my reading).
The copper gives green or blue color and the cadmium red.
Now,if i rub a vinegar(with a cotton rag??i didn't understood,exactly,the rub process) on the silver brazing rod.After that,take some of the liquid of the rubbing liquid(from the wet brazing rod?from the wetted cotton rag?)put on a the tip of clean copper wire and into the flame,i should see only a green color if there is not cadimium in the rod or a mixture of green flame(copper)and red flame(cadimium)if the rod contains cadmium.(though i don't know if the mixture of color will be as the mixture of light colors-yellow).
Is it right?the process and the results that i might get?
The cadmium has lower melting point than the copper but i don't know if it is mean that i will see the red flame first before the green(or the mixture color)when i put the copper wire tip in the flame.
Do you have any idea?

[Corribus]

Most Universities have an ICP-MS somewhere. Maybe you can talk someone into running a sample for you.

[Arkcon]

(though i don't know if the mixture of color will be as the mixture of light colors-yellow).

This is more likely what you will see, if you try to do a flame test.  You also might not even see it.  If you don't have someone who will do an ICP, or a AAS for you, you'd be best to just ask the manufacturer.  Your ability to detect trace levels of metals isn't going to be that great with a vinegar wipe.

[xchcui]

I don't have any access to ICP or a AAS.
All the idea is to test the silver brazing rod by yourself,because it,probably,will not be one time test and not all times i can know where the brazing rod made in?
If i will get a yellow flame(as you confirm that i will more likely to get)that will be created as the result of the cadmium+copper from the brazing rod,it will be good enough for me,since it will show that the brazing rod contains cadmium.I don't need to know,exactly,what other elements(percentage and types)there are in the brazing rod.
So,the ideal solution is the flame test,though i haven't understood entirely the process.
Can you explain how should i rub the vinegar on the brazing rod?should i take cotton rag,dip it in vinegar and rub the object?
And later,what should i put on the copper wire tip?
The liquid from the cotton rag?or directly fromthe wetted brazing rod?

[Arkcon]

Start with this:  http://en.wikipedia.org/wiki/Flame_test  That article also has external links that will provide you with more specific instructions.  You will need all of the instructions, and some practice, to have a chance of success.  Your last two paragraphs of questions lead me to believe that you think you are a few questions away from a prefect solution.  You're not, you're days away from a slapdash procedure that's been lost to the annals of analytical chemistry prehistory.  You're just lucky I'm old enough to have even heard of this sort of thing -- when I did flame AA in college, in the 1990's, the young kids didn't even know certain metals colored some flames.

I would suspect the best way to do it would be to shave a few metal filings, and dissolve the filings in analytical grade nitric acid.  Vinegar is just ridiculous, the metal won't dissolve in such a weak, dilute acid.  Farly inert metals, like silver and copper will shield any cadmium from even strong acids.  No, the sample must go completely into solution, or you're not analyzing anything at all.  The quoted articles tell you a bit about what sort of flame you need.  Read that carefully, and don't trouble us to analyze further shortcuts you devise.

Please realize that sodium ions are ubiquitous and color any flame yellow, and if you only have traces of metals, any yellow color is suspect.

Now if you had a diffraction grating, and could get a spectrum off the flame, and you built standards -- saw the lines of a pure copper flame, and a pure cadmium flame, then you might have a useful diagnostic procedure.  But that seems like a silly amount of work for a one-off test.  You can see what you can get here: http://jersey.uoregon.edu/vlab/elements/Elements.html

Why, exactly, is it impossible to check with the manufacturer?

[xchcui]

As i mentioned before,i don't have any details on the brazing rods and i don't know who made them.If i knew that,why would i need all that flame test headache.
I understand that the vinegar is too weak,but it is not worth to me to buy and deal with nitric acid either.
Maybe the method with the vinegar is just a waste of time(and i more than believe that you are know what you are saying),but it is the only method that i can do and i would like to try it,anyway.(i can't do the other methods).
What is it mean"rub the vinegar on the object"?
and from where and how to pick up a little of the liquid?
My questions refer to that instructions:

Anyway there's your answer. Rub a little acid (vinegar would probably do the trick) on the plating, then use the end of a bit of clean copper wire to pick up a little of the liquid and see if you get a red flame (before the copper gets too hot and gives you a green one)

Again,i understand that it,maybe won't work,but it is my only possibility.

[xchcui]

If you want to answer my question(the same question about the procedure with the vinegar that i asked three times and never got an answer)i will very appreciate that.
If not,so,thanks for your responses.
Bye