Single monitoring wells

A single monitoring well can be designed to accommodate all of these uses and wells are usually designed to collect only those data required by the groundwater monitoring plan. 

T cell activation results in the proliferation of primary T cells in culture, which can be measured directly by monitoring the rate of DNA synthesis. Metabolic incorporation of tritiated thymidine ( H-TdR) into cellular DNA is the most commonly used method, because it is highly sensitive and allows detection of poorly proliferating cells such as primary T cells. In addition, the H-TdR incorporation assay is time and cost effective and offers the possibility to screen the effects of several inhibitors, culture conditions, stimulations, etc. in a single 96-well plate. 

Treatment with rifampicin 600 mg daily for 14 days markedly affected the pharmacokinetics of a single 150-mg dose of pirmenol in 12 healthy subjects. The apparent plasma clearance increased sevenfold and the AUC decreased by 83%. The probable reason is that rifampicin increases the hepatic metabolism of pirmenol. Monitor well and anticipate the need to increase the dosage of pirmenol if rifampicin is used concurrently. 

A second use of arrays arises in the detection of trace components of material introduced into a mass spectrometer. For such very small quantities, it may well be that, by the time a scan has been carried out by a mass spectrometer with a point ion collector, the tiny amount of substance may have disappeared before the scan has been completed. An array collector overcomes this problem. Often, the problem of detecting trace amounts of a substance using a point ion collector is overcome by measuring not the whole mass spectrum but only one characteristic m/z value (single ion monitoring or single ion detection). However, unlike array detection, this single-ion detection method does not provide the whole spectrum, and an identification based on only one m/z value may well be open to misinterpretation and error. 

How then are these ions/decompositions chosen Before considering this we must define, very carefully, the requirements of the analysis to be carried out. Is a single compound to be determined or are a number of compounds of interest If a single compound is involved, its mass spectrum and MS-MS spectra can be obtained and scrutinized for any appropriate ions or decompositions. If the requirement is to determine a number of analytes, their chromatographic properties need to be considered. If they are well separated, different ions/decompositions can be monitored for discrete time-periods as each compound elutes, thus obtaining the maximum sensitivity for each analyte. If the analytes are not well separated, this approach may not be possible and it may then be necessary to monitor a number of ions/decompositions for the complete duration of the analysis. If this is the case, the analyst should attempt to find the smallest number of ions/decompositions that give adequate performance for all of the analytes (remember the more ions/decompositions monitored, then the lower the overall sensitivity will be). 

In a different context, a micropipette has been applied to monitor the current through a single-ion channel in a biological membrane. The patch-clamp technique invented by Sackmann and Neher [119] led to their Nobel Prize in medicine. The variations in channel current with voltage, concentration, type of ions, and type of channels have been explored. While the functions of specific channels, in particular their ionic selectivity, have been well known, only a handful of channels have the internal geometry and charge distribution determined. The development of a theory to interpret the mass of channel data and to predict channel action is still lacking. 

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