Since HAuCl4.3H2O (gold precusor) is very expensive, it is best to utilized it as much as possible. I have a glass vial that contains such gold precursor. Some of it are spread onto the inner surface of the glass vial due to moisture absorption when I'm trying to weight some of the crystal for chemical preparation. Is it possible to add deionized water to the glass vial after all of the crystal are taken out to dissolve them and use UV-Vis spectrometer to determine the concentration of the dissolved precursor?
Or can I use micropipette to measure the weight of 10 mL DI water on one analytical balance, drawn another 10 mL and place into the vial, gently shake it, take out 5 mL and measure the weight of the solution to determine the gold precursor concentration?
Soo Yew Hang You have found one of the major issues with chloroauric acid. It is highly hygroscopic. I always thought it was the tetrahydate (HAuCl4.4H2O) but always formulated it as HAuCl4.xH2O.
Obviously you can work quickly but it is better to make up your solutions and then determine the Au content by AAS or ICP (or as you suggest with UV-VIS). I made supported Au catalysts via reduction of absorbed chloroauric acid in the 1970's that had an objective of 5 wt% metal on the (inert?) support. In practice the catalysts tended to have a content of ~ 4.5%. Some was lost on washing. Some got absorbed somewhere else. There may have been slightly more water from the hygroscopic take up of the salt on weighing but this couldn't account for 0.5% loss.
Key question to ask you - what are you doing with the Au precursor? What's the application?
BTW, there are more expensive (PG) metals than gold. Try Ir, Os, Rh or Re next time...
Alan F Rawle Thanks for the suggestion. I have ICP here as well, might try that one later. I am doing Au doped TiO2 nanotube for visible light photocatalysis.
But now I'm switching to silver nitrate as it is way cheaper and easier to handle. Once i mastered silver deposition then I might switch back to the Au given that it is so little inside the container.
Soo Yew Hang I also made supported Ag-SiO2 catalysts as well as Pd-Au and Pd-Ag. In air or in the presence of oxygen (from water or from the support) you'll find that your silver materials are not actually silver on the surface (from XPS) - it will be in the +1 oxidation state (i.e. Ag2O) which reduced easily to silver metal. It's Ag+ that's the bactericide. This webinar may be helpful:
September 2nd, 2015 Silver colloids and invisible ink
https://www.brainshark.com/malvern/vu?pi=560497681&b=1&tx=120486&c1=22
- Badges
- Science topic
- Similar topics
- Physical Sciences
- Materials Science
- Materials
- Inorganic Materials
- Ceramics
- Glass