Agilent 7500a ICP-MS 

(Inductively Coupled Plasma - Mass Spectrometer)

 

Our ICP-MS is located in a class 100 clean room for trace element analysis of water, soil, sediment, rocks/minerals, tissues, etc.

Typical detection limits are in the ppt range for most metals and low ppb range for non-metals such as P and S.

Theory:

Liquid samples (typically aquous samples stabilized in nitric acid) are taken up automatically from pre programmed autosampler positions.  A nebulizer is used to aspirate samples into a fine mist, and a peltier chilled double pass spray chamber is used to remove large drops and reduce the water vapor content of the aerosol. The aerosol is then injected into the argon plasma at ~8000K (14,000 ºF) where it is decomposed and ionized.  Positively charged ions are then injected in the mass spectrometer, focused, and sorted by their mass to charge ratio (m/z) before being counted by an electron multiplier (pulse counting detector).

  1. Nebulizer and spray chamber (generates and conditions the aerosol)
  2. Peristaltic pump (controls liquid flows: sample, internal standard, waste etc)
  3. Working Platform (holds sample accessories)
  4. Torch box (contains Inductively Coupled Plasma)
  5. Interface region (skimmer and sampling cones transition the ions to a high vacuum)
  6. Extraction and ion focusing lenses (Einzel and Omega lens assembly
  7. Quadrupole mass filter selects analyte ion based on mass/charge ratio (m/z)
  8. Other masses are ejected
  9. Pulse counting detector (analyte ions are counted - data is for each mass is generated in units of counts per second, cps)
  10. A combination of mechanical (rotary vane) and turbomolecular pumps establish the high vacuum within the mass spectrometer)

 

1, 2, 4. Nebulizer, Spray Chamber, Peristaltic Pump, and Torch Box

4, 5. Torch Box and Interface (Sampler Cone)

4, 5. Torch Box and Interface (Skimmer Cone)

Inductively Coupled Plasma - ICP (Temp ~8000K)

6-9.  Lenses, quadrupole assembly, and detector (L-R) within the vacuum chamber

6. Close up of Einzel and Omega lense assembly. The quadrupole is as the bottom of this image, and the interface region is at the very top.