Stability of a HAuCl4 solution

[LionHeart]

Does anyone know about the stability of a HAuCl4 solution. Just received some crystals, and it would be more practical for me to just make one solution, although I'm not gonna need it all for colloidal gold production right away. Is it possible to store a HAuCl4 solution for months for later colloidal gold productions?

[kephra]

It keeps indefinitely if the bottle is kept sealed.

[LionHeart]

Thanks Kephra. Should be stored in the refrigerator or room temperature?

[kephra]

Just room temp.
If you got powder, was the formula weight listed on it?
You need to know that to figure out the dilution ratio.

[LionHeart]

Ok

No weight, but it is tetrahydrate. I've made a 250ml 0,0466M solution. Now I just have to figure out how much herb I should use to reduce it.

I want to make 1L 100ppm colloidal gold. How much of the solution should I add? and how much herb do you recommend I use? 

[kephra]

Do you have HAuCl4 or AuCL3 tetrahydrate?

[LionHeart]

I have HAuCl4 tetrahydrate

[LionHeart]

it has a molar weight = 411,85g/mol

[kephra]

it has a molar weight = 411,85g/mol

So, gold with an atomic weight of 197 is about 48% of the weight of the gold chloride.
Then you need 209 milligrams of your gold chloride in 1 liter to make 100 ppm
You need 10 times the amount of additives as with the formulas for 250ml of 40 ppm colloidal gold listed on the forum.

[LionHeart]

Ok

I've calculated that I need to at 11ml of my 0,0466M solution to get 1 L of 100 ppm.
When you write additives are you referring to the reducing agent?

[kephra]

I'm referring to anything other than the gold chloride according to the posted formulas.  IE: sodium carbonate, or maltodextrin, etc.

[LionHeart]

Not sure I follow. It's pure HAuCl4, and I intend to add a herbal reducing/capping agent, and nothing else. I just have to figure out how much to use. Do you recommend I add 10 times the amount of a herbal extract.

[kephra]

Well, if its not something I have tried already, I really can't say.
I make mine with sodium carbonate and maltodextrin, which is totally reliable.
If you are going to use something else, I would suggest just making a 50ml batch to test out your herbal extract.  That way, you wont waste as much gold. 

[RickinWI]

Not sure I follow. It's pure HAuCl4, and I intend to add a herbal reducing/capping agent, and nothing else. I just have to figure out how much to use. Do you recommend I add 10 times the amount of a herbal extract.

Since there are 2 other components to the formula in addition to the gold chloride, I think it would be reasonable to assume that they are both there for a reason and that they each perform a specific function.

The maltodextrin (or Karo, if one so chooses) is the reducer/stabilizer.  I think the sodium carbonate is there to raise the pH up into the range where the maltodextrin can be effective.

It would be quite a stroke of luck to stumble across the right herb or herb extract that has the ability to perform both of these functions.

Remember gold chloride itself is toxic so it's important to make sure that you fully reduce it to colloidal gold.

[LionHeart]

Many different herbs have been used to make colloidal gold, because they are all loaded with reducing agents, aka antioxidants, so I wouldn't call it a stroke of luck to find a herb that can reduce gold chloride, on the contrary I would be very surprised if you can find a herb not able to reduce.

I'm more concerned with the proper doses of the herb. What is the effect of using excessive amounts of reducing agent? Does it have any influence on particle size or stability?

The reason why I want to use herb solely and not maltodextrin or citrate, is because I want to make sure that it is polyphenols from the herbs, and not maltodextrin or citrate, that are attached to the gold particles, so that the may be transported into tissues by the gold carrier. The use of nanoparticle carrier systems are being researched extensively in the field of medical nanotechnology, but as we discussed in another thread, there might be some issues with overcoming digestion when taken orally. However I'm willing to try it out.