Sercon Ltd. - 20-20 Continuous flow isotope ratio mass spectrometer

The 20-20 is the dedicated continuous flow isotope ratio mass spectrometer for hyphenated stable isotope analyses.

An extensive range of automated sample preparation units gives the researcher the flexibility to measure ¹⁵N, ¹³C, ¹⁸O and ³⁴S in a host of applications. It is the only analyser that has been purposely designed to measure ²H by continuous flow methodology.

The novel 120° ion optics came out of a design study to find the best geometry for both dual-inlet and continuous flow use and to improve sensitivity for new applications. True stigmatic focusing results in high sensitivity. Novel ion optical design results in an instrument having high dispersion with a short ion path length. This gives exceptionally high stability and has the distinct advantage of low abundance sensitivity when being used for continuous-flow. The high dispersion hydrogen spur gives complete separation of HD from He without the need for shields or voltage driven retardation grids.

Key Features Include:

• 120° extended geometry with an 11 cm radius magnetic sector giving an effective 21 cm radius dispersion and double direction focusing. Additional high dispersion long spur with 98.8° sector which creates a distance of 24 cm between the focal points for m/z 2 and 3. This leads to an abundance sensitivity at m/z 3 of <1 ppm which eliminates helium ‘tailing’ in to the D/H collector.
  
  
• Truly universal Faraday triple collectors for simultaneous collection of adjacent masses in the range 28,29,30 - 64,65,66 with no adjustment of collectors or amplifiers. Additional single Faraday collector and high gain amplifier for m/z 3 on the hydrogen spur. The desired combination of the 4 collectors is selected through the software.
  
  
• Asymmetric extended geometry to give true stigmatic focusing with twice the dispersion of normal geometry with the same radius sector.
  
  
• Shorter path length than traditional extended geometry to decrease ion/molecule interactions and so ensure 100% transmission through the analyser and a sensitivity which is higher than any other commercial IRMS (<1000 molecules/ion for CO₂).
  
  
• Small analyser footprint and wide flat peak shape reduce the effect of temperature drift therefore removing the need for peak centering during analysis.
  
  
• Design allows greater tolerance of the known variables of ion optics making the manufacture of the analyser more reproducible and less sensitive to magnet positioning.
  
  
• True differential pumping by turbo-molecular pumps with a high compression ratio for both He and H2, to remove the detrimental effect of abundance sensitivity during continuous flow applications and eliminate memory.
  
  
• Suitable for the analysis of light stable isotopes in all the commonly measured gases; H₂, N₂, NO, N₂O, O₂, CO, CO₂, SO and SO₂.
  
  
• Option to use one or more patented reference gas injection modules at operator defined times controlled through our proprietry IRMS software. This set-up was developed in technical collaboration with Dr Wolfram Meier-Augenstein at Queens University Belfast.
  
  
• Data acquisition system uses state of the art highly stable and linear high frequency converters which produce integral slices with zero dead time and quantisation below the beam statistical noise floor at all signal levels.