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The multi-dynode approach of all ETP electron multipliers results in longer lifetimes—and better sensitivity—compared with channel electron multipliers (CEM) or continuous-dynode multipliers.
The electron multipliers manufactured by ETP use a proprietary dynode material. This material has a number of properties that make it very suitable for use in an electron multiplier. It has very high secondary electron emission, which allows exceptional gain to be achieved from each dynode. This material is also very stable in air. In fact, an ETP multiplier can be stored for years before being used. As a direct result of the high stability of the active materials used in ETP multipliers, they come with a two-year shelf life warranty (stored in original, sealed package). Many testing laboratories take advantage of this long shelf life by keeping a replacement ETP multiplier on hand, ready for immediate installation. This keeps instrument downtime to a minimum.
For a typical ETP electron multiplier for GC-MS, the total active dynode surface area is ~1000 mm2. This can be compared to a standard continuous dynode multiplier that has a total channel surface area of only around 160 mm2 (for a channel with 1 mm diameter and 50 mm length). This increased surface area spreads out the workload of the electron multiplication process over a larger area, effectively slowing the aging process and improving operating life and gain stability.