Collision/reaction interface

ICP Mass Spectrometers with Collision or Dynamic Reaction Cell or Collision Reaction Interface... 

Collision/reaction cell Agilent ceVcs2 octopole cell (ORS) Elan DRC II quadrupole dynamic reaction cell XSeries11 hexapole cell ( XS-Minus modus) Varian-820-MS using collision reaction interface... 

The cold/cool plasma approach, which uses a lower temperature to reduce the formation of the argon-based interferences, has been a very effective way to get around some of these problems. However, this approach can sometimes be difficult to optimize, is only suitable for a few of the interferences, is susceptible to more severe matrix effects, and it can be time consuming to change back and forth between normal and cool plasma conditions. These limitations and the desire to improve performance have led to the commercialization of collision/reaction cells (CRC) and collision/reaction interfaces (CRl). Designs for CRC and CRl were based on the early work of Rowan and Houk, who used Xe and CH4 in the late 1980s to reduce the formation of ArO+ and Ar2 species in the determination of Fe and Se with a modified tandem mass spectrometer. This research was investigated further by... 

The collision/reaction interface, which will be discussed later in this chapter, uses a slightly different principle to remove the interfering ions. It does not use a pressurized cell before the mass analyzer, but instead, injects a reaction/collision gas directly into the interface between the sampler and skimmer cones. The injection of the collision/reaction into this region of the ion beam produces collisions between the argon gas and the injected gas molecules, and as a result, argon-based polyatomic interferences are destroyed or removed before they are extracted into the ion optics. 

Let us now go on to discuss the newest approach to reduce interferences using collision/reaction chemistry—the collision/reaction interface. 

FIGURE 10.8 Principles of the collision/reaction interface (CRI) (courtesy of Varian Instruments Inc.). 

Typical Detection Limits in Parts per Trillion (ppt) of a Dynamic Reaction Cell (DRC), an Octapole-Based Collision/Reaction Cell (CRC), and a Collision/Reaction Interface System (CRI)... 

X. D. Wang and I. Kalinitchenko, Principles and Performance of the Collision Reaction Interface of the Varian 820-MS, Varian Instruments ICP-MS Advantage Note, 1, October 2005 http //www.varianinc.com/image/vimage/docs/applications/apps/icpms anl.pdf. 

When assessing the capabilities of collision and reaction cells, it is important to understand the level of interference rejection that is achievable, which will be reflected in the instrument s DL and BEC values for the particular analytes being determined. This has been described in greater detail in Chapter 10, but depending on the nature of interference being reduced, there will be differences between the collision/reaction cell methods as well as with the collision/reaction interface approach. It is therefore critical to evaluate the capabilities of commercial instrumentation on the basis of your sample matrices and particular analytes of interest. 

However, it should be emphasized that when you are comparing systems, it should be done with your particular analytical problem in mind. In other words, evaluate the interference suppression capabilities of the different collision and reaction cell interface approaches by measuring BEC and DL performance for the suite of elements and sample matrices you are interested in. In other words, make sure it works for your application problem. This is even more important with the collision/ reaction interface because it works on a slightly different principle, and as it does not use a traditional cell, it is unclear how it discriminates between all the generated by-product interfering ions from the analyte ions. 

The collision/reaction interface looks to be a very interesting concept, which appears to offer a relatively straightforward, noncell-based solution to minimizing plasma- and matrix-based spectral interferences in ICP-MS. Each year more and more challenging applications appear in the public domain showing the capabilities of collision/reaction interface systems. If there is an interest in this approach, it is worth checking out the vendor application notes, which show the capabilities of the collision/reaction interface in many different, real-world matrices. ... 

---