[valatmck]

I am working on my senior thesis, trying to determine the cyanide content in different malt beverage (ie:  beer), and am having a very difficult time located any resources on this topic, and was wondering if you might be able to provide some assistance with finding resources, or suggesting a method of analysis.

[hmx9123]

You could try some analytical chem books, quantitative analysis books, or spot tests in inorganic chemistry.  However, I think that copper can be used as an analyte.  You will have problems with all the other junk in beer getting in the way of the reagent--there's a very complex mix of material there.

[Garneck]

Well, I believe cyanide would be on some really small level in that beer. You could use a potentiometric method with a Ag/AgCl electrode, but I guess you would have some problems with Cl-.

Let me think. Kso for AgCN = 2,0*10^-16 and Kso for AgCl = 1,1*10^-10, so that would be a selective method if the ratio Cl-/CN- is lower than 10⁵/1. I think that would work.

Correct me if I'm wrong.

[keefhalek]

I've done cyanide determination myself and there is a company that sells very simple kits.  They are called Chemetrics (www.chemetrics.com). :1eye:

[Dedalus]

You picked a tough problem!

Cyanide analysis generally requires a preliminary distillation, in which sulfuric acid, magnesium chloride, and sulfamic acid are added, and air pulled through the sample, which is then brought to a boil. The water vapor is recondensed, and the air is directed through a sparging stone immersed in a sodium hydroxide solution. After a hour of boiling, the original sample  is discarded, and the sodium hydroxide solution analyzed for cyanide. This method will go down to 5 ppb, easily.

The problem arises because of interferences. Aldehydes and sugars,  which are abundant in beer, react with the cyanide during the distillation to form cyanohydrins, which are not recovered. There is another procedure, weak and dissociable cyanide, where an acetic acid buffer is used instead, but this does not recover all of the cyanide.

You might have luck with an ISE based technique as Garneck suggested, using the method of standard additions.

Good luck!

[kevins]

I've done cyanide determination myself and there is a company that sells very simple kits.  They are called Chemetrics (www.chemetrics.com). :1eye:

Chemetrics is good in trace analysis for clean water sample. For the color sample such as beer, I think distillation is required to remove the intereference and color.
Please try.

[Garneck]

Or anion exchange chromatography..