Selection of probes

Table 4.1. Conceptional criteria for the selection of probe molecule to characterize solid acids (from ref. [31])...

Successful flow cytometric analysis depends on adequate sample preparation (see Chapters 30-31), appropriate selection of probes or markers (see Subheading 2.), instrumentation, and data display and analysis. Each of these areas is interrelated and requires adequate attention to avoid the introduction of artifacts and misinterpretation of results. Flow cytometers tend to be excessively complicated and require a skilled operator for alignment and calibration, though manufacturers are introducing more compact, user-friendly data acquisition and image processing systems. 

Criteria for recording thresholds and selection of probes angle with MDU system. 

In some process examples, the reaction environment are relatively mild. The majority of process environments, however, are more challenging with both elevated temperatures and pressures. When faced with a new on-line trial, one of the first questions that needs to be addressed is how to interface to the process of interest. In this subsection, examples will be provided in order to facilitate an appropriate selection of probe to sample interfaces. 

A ratiometric sensor 4 for Cd " and Zn " based on calix[4]arene bearing 1,2,3-triazole-linked pyrene units has been reported (Fig. 28.2) [30]. Probe 4 showed strong excimer and weak monomer emissions, due to face-to-face jt-interactions. Addition of Cd " or Zn produced a ratiometric fluorescence change, with a decrease in excimer emission and an increase in monomer enussion. This ratiometric behavior is due to the complexation of Cd " and Zn " by the triazole nitrogen atoms, which causes a change in the conformation of the pyrene arms. No other metal ions produced such ratiometric response, confirming the high selectivity of probe 4. 

Electrochemical probes are available that measure the concentration of dissolved oxygen in both conducting and non-conducting media. Care has to be taken in the selection of probe type, as with some the elements are easily poisoned by certain species within the process fluid. 

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