Secondary count gain

We should not forget that an appropriate detector, a Faraday cup or a secondary electron multiplier equipped with a conversion dynode, is needed for ion detection. Most commercial instruments are equipped with a secondary electron multiplier, which can be operated in a low amplification mode, the analogue mode, and with a high gain, the counting mode, where each ion is counted. With this dual mode, a linear dynamic range of up to nine orders of magnitude can be achieved, so that major and minor components of the sample can be measured in one run. 

Interleukin-11 is the first growth factor to gain FDA approval for treatment of thrombocytopenia. It is approved for the secondary prevention of thrombocytopenia in patients receiving cytotoxic chemotherapy for treatment of nonmyeloid cancers. Clinical trials show that it reduces the number of platelet transfusions required by patients who experienced severe thrombocytopenia after a previous cycle of chemotherapy. Although IL-11 has broad stimulatory effects on hematopoietic cell lineages in vitro, it does not appear to have significant effects on the leukopenia or neutropenia caused by myelosuppressive chemotherapy. Interleukin-11 is given by subcutaneous injection at a dose of 50 g/kg/d. It is started 6-24 hours after completion of chemotherapy and continued for 14-21 days or until the platelet count passes the nadir and rises to > 50,000 cells/ L. 

The basic principles of discrete-dynode electron multiplier operation are shown schematically in Figure 3.1. When an ion strikes the first dynode of a discrete-dynode electron multiplier (or conversion dynode) it liberates secondary electrons. The electron-optics of the dynodes then accelerates these electrons to the next dynode in the multiplier, which in turn produces a greater number of secondary electrons. This process is repeated at each subsequent dynode, generating a cascade of millions of electrons, which are finally captured (as an output pulse , hence the term pulse counting) at the multiplier output electrode. The gain of an electron multiplier can be defined as the average number of electrons collected at the multiplier s output electrode for each input ion that initiates an electron cascade. Similarly, it can be described as the current measured from the output divided by the input ion current. It should be noted that this second definition includes the ion detection efficiency of the multiplier. 

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