Inductively Coupled Plasma - Mass Spectrometry

Louvain-La-Neuve

The Mass Spectrometry is a technique of separation, identification and quantification of elements according to their mass. It is based on the coupling of a plasma torch generating ions and a quadrupole mass spectrometer which separates these ions in mass.

Part of the ions generated by the plasma is sampled by a first cone (sampler) then by a second (skimmer). A differential vacuum system accelerates the ions to a set of electrostatic lenses which extracts the positive ions and transports them to the quadrupole mass filter.

A gas (helium) is introduced into the cell (added to the ion optics) which will react or collide with isobaric or poly-atomic interference and thereby destroy them while letting the targeted ions pass through enough for the mass spectrometer. The four cylindrical bars that compose it are separated into two opposite pairs and subjected to direct and alternating current.

Depending on the applied voltages, only the ions with the desired m/z (mass/charge) ratio will be transmitted to the detector (composed of an electron multiplier with dynodes subjected to a negative voltage).

The signal occurs in numbers of pulses.

For a given isotope, the number of ions measured makes it possible to directly calculate the concentration of the element analyzed using software allowing the quantitative and qualitative processing of the recording.

 

Applications of this technique:

Mineral matrices:

  • Chemical analysis of Soils and Waters: major elements (Ca, K, Na, Mg, P, Al, Fe, Mn, S) and ETM - metallic elements in trace form (B, Cd, Cu, Pb, Zn)
  • Determination of S in thermal waters
  • Catalyst tracking

Biological matrices:

  • Detection of heavy metals (As, Cd, Hg) in plants,
  • Zn, Cu and Se content in bull semen
  • Al dosage - Eel toxicity study
  • Determination of Cd in cocoa beans