Generation of Reagents in Statu Nascendi

The applicability of unstable reagents might not be restricted to reducing and oxidizing agents, but may well provide similar advantages for other types of reactions and in solvents other than water. 

As rightly pointed out recently by Luque de Castro and Valcarcel [1044], the term simultaneous is not cearly defined in FIA because it has been indiscrimanately used to describe different alternatives. Hence, in their paper, they attempted to establish the difference between multidetection and multidetermination, and the sequential and simultaneous variants of each of these, arriving at the following definitions  

Multidetermination. Determination of two or more analytes on a sample. It can be (a) sequential, determining n analytes from n injections of the same sample or (b) simultaneous, determining several analytes from a single sample injection. 

Turning initially to multidetection, and here first to simultaneous usage, an obvious application is to combine the gradient FIA techniques with the use of detectors that provide several signals at several values of the instrumental variables, which indeed gives FIA a doubly dynamic character. In these techniques, which have already been mentioned in Section 2.4, advantage can be taken by multidetectors, such as the fast-scan vol-tammetric detectors [288] or by inductively coupled plasma atomic emission spectroscopy [808] or by diode array detectors [1017, 1075, 1382]. Combined with the advantages offered by chemometrics, these multidetection procedures may in fact be extended to multideterminations. 

An example of simultaneous multidetermination executed via a single injection and employing several detectors has in fact already been mentioned in Section 4.1, where the simultaneous determination of pH and pCa [21] was presented (Fig. 4.4). Another similar application is the scheme presented by Virtanen [250] for the determination of Na, K , Ca , and Cl in serum by the use of ion-selective electrodes in which system the flow impinged laterally on both the sensors and the reference electrode, which was located behind them and in the same position, an 

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