Recent Advances in Ion-Selective Membrane Electrodes for In Situ Environmental Water Analysis
On-board, on-site and in situ approaches
tải về 1.01 Mb. Chế độ xem pdf
|
uftai-ve-tai-day27945
|
3. On-board, on-site and in situ approaches. Figure 3 depicts the three most common decentralized path measurements for environmental water research (i.e., on-board , on-site and in situ configurations). The on-board approach implies the portability of the analytical device for shipboard measurements (Figure 3a). The employment of powerful pumps retrieving water at different depths from a ship, which can be fixed at different locations of the studied area, confers to the recorded concentration maps spatial resolution in two dimensions. However, the on-site concept involves measuring from a platform directly placed in the explored area (Figure 3b) and, therefore, the limitations of instrument portability are not as restrictive as in the case of on-board measurements. Although the same type of pumps can be utilized in this 13 context, only profiling at different depths is possible, thereby restricting the spatial resolution of the obtained profiles. The in situ concept involves the development of a submersible probe containing the analytical instrument (Figure 3c), which can be controlled from a ship, hence providing the highest spatial and time resolution of the three approaches. Evidently, not all the analytical techniques are suitable for on-board and on-site water measurements, and, to a lesser extent, for in situ monitoring because of the special requirements. Indeed, ISEs have been implemented into these configurations and various examples of real water monitoring are reported in the literature. In this regard, a novel setup based on a flow cell including eight ISEs of inner-filling solution type together with one commercial reference electrode (RE) coupled in turn to a sampling system has been recently published (Figure 4).[103] For this purpose, the cell is implemented into a flow setup connected to a system for retrieving water from different depths placed on a platform in a lake. This is therefore an on-site approach but it could be also be easily adapted for the tải về 1.01 Mb. Chia sẻ với bạn bè của bạn:
|