Procedure for Measuring the Concentration of Palladium
I would like to use ICP-MS to measure the concentration of palladium. May I know how do I dissolve Pd/SBA-15 and what are the precautions I should taken while I prepare the samples?
SBA-15 is the mixture of poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) [Pluronic 123), (C3H6O.C2H4O)x and tetraethyl orthosilicate (TEOS), C8H20O4Si.
For TEOS, Boiling point 163 - 167 °C, Ignition temperature 230 °C, No melting point is provided.
The catalyst that I make is in powder form. 90% is the SBA-15.
The procedure to use is as follows:
- Weigh the sample into a clean crucible made of quartz (or fused silica or Porcelain).
- Heat the sample on a hot plate to a char. If a large (1+ grams up to 50 grams) amount of sample is required to meet either sensitivity/detection limit requirements or sample homogeneity issues then heat the sample to a liquid that can be ignited. This takes special precautions due to a flame coming off and fire safety issues but this approach allows you to deal with large quantities of sample and achieve rapid preparations or large batches with excellent detection limits. Please note also that the actual sample (below the flame) only get up to the hot plate temperature.
- After the sample has burned down to a char - wet the char with 1-3 drops of sulfuric acid and heat on a hot plate until the SO3 fumes cease.
- Place the charred/fumed sample into a muffle furnace at 450 deg C and ash for 2-3 hours.
- Remove the crucible and allow to cool - dissolve the Pd by carefully adding ~ 1 mL of freshly prepared Aqua Regia (3:1 v/v HCl:HNO3). The Pd should go into solution rapidly. Pd is also quite soluble in concentrated nitric acid with the addition of just a few micro liters of conc. HCl - this may be easier (if Aqua Regia is not preferred - to the char add 1-5 mL of concentrated nitric acid and bring to fumes on a hot plate- add 10 uL of conc. HCl and continue to heat. The Pd, which may be present as the metal (Pd is very easily reduced to the metal when heated in the presence of organics), should dissolve easily.
- Dilute the digestate and make up to 1 to 2 % v/v nitric acid for ICP-MS measurement.
I always recommend that the analyst perform a method validation study with any new or revised procedure. Please let me know if you have any questions.
Serving you in chemistry,
Paul R. Gaines, Ph.D.
CEO of Inorganic Ventures & Fellow Chemist
DISCLAIMER: Advice offered by the chemists at Inorganic Ventures is intended for the individual posing the question. Feel free to contact us to verify whether these suggestions apply to your unique circumstances.