Platinum Labware Use and Maintenance

APPLICATION AND LIMITATIONS

FUSIONS:

The Pure platinum recipients can be used to melt the following;
  1. Sodium or Potassium carbonate.
  2. Sodium carbonate, sodium nitrite or nitrate.
  3. Sodium borate or sodium metaphosphate. (The platinum is slightly attacked at very high temperature or in reducing atmosphere.
  4. Alkaline bifluorides.
  5. Alkaline bisulphate. (The platinum is slightly attacked above 700 degree centigrade; this can be reduced through the addition of ammonium sulphate)
  6. Alkaline or alkaline earth chlorides in natural atmosphere (The platinum is slightly attacked in the presence of air and above 1000 degree centigrade through the release of chlorine. There is no attack in natural atmosphere.
Nevertheless, platinum does have certain application limits.
Thus the following should not be melted in such recipients.
  1. Free metals.
  2. Alkaline Oxides, hydroxides and peroxides.
  3. Salts of heavy metals (Lead, Tin, Bismuth, Antimony) as well as their organic compounds.
  4. Phosphates in the presence of substances which reduce compounds capable of releasing chlorine.
  5. Cyanides or sulphides.

EVAPORATION:

The pure platinum recipients may be used for evaporation with:
  1. Sulphuric acid in the presence or absence of hydrofluoric acid.
  2. Hydrofluoric acid in the absence of chlorides and other halides.
  3. Hydrochloric acid in absence of oxidizing agents.
  4. Hydroxides or alkaline carbonates.
All basic or neutral solutions may be evaporated in platinum recipient, as can acid solutions except for those containing hydrochloric acid in the presence of an oxidizing agent.

MAINTENANCE & CLEANING:

Cleaning & polishing platinum apparatus immediately after use greatly extend their service lives. Immediately after use, the platinum recipients are to be cleaned:
  1. Either by pouring nitric acid solution (diluted with hydrogen peroxide if need be) or a hydrochloric solution in to them.
  2. Or by melting potassium bisulphate, sodium carbonate or borax in them.
Aqua regia or hydrochloric acid in the presence of peroxide are not suited for this owing to the formation of free chlorine which dissolves the platinum.