Acidification monitoring

An automated standard addition technique is part of the analytical protocol. An aliquot of a "Tc standard solution is added to a duplicate of the sample during acidification. The "Tc standard is in a nitric acid solution of the same concentration used for sample acidification. To perform the standard addition measurement, the sample acidification monitor instrument automatically substitutes a given volume of the "Tc standard solution for an equal volume of the nitric acid. The volume of the standard solution is selected by the software to yield an estimated threefold higher signal relative to the analysis of an unspiked sample. 

Daleke DL, Hong K, Papahadjopoulos D. Endocytosis of liposomes by macrophages binding, acidification and leakage of liposomes monitored by a new fluorescence assay. Biochim Biophys Acta 1990 1024(2) 352-366. 

Similar results were reported in the literature for most European (Scandinavia, UK, Germany, Poland and Czech Republic) and North American (Ontario, Vermont, Quebec, Adirondack Mountains, Appalachian Mountains, Blue Ridge Mountains) freshwater sites, where monitoring of the effects of long-range transboundary air pollution on acidification occurs [23]. 

Cytosensor Microphysiometer technology has been used to detect perturbation in mammalian cells (Hafner, 2000). The system measures small changes in extracellular acidification using a light addressable potentiometric sensor. If the metabolism is interfered with, acid excretion will be affected which could be sensitively measured by LAPS. In principle, this system should be suitable for monitoring pathogen interaction with mammalian cells. 

During mineralization acidification occurs [19,20]. Since Ti02 is a photocatalyst of the process and is also able to behave as pH sensor, it is in a position to activate a process and to monitor its proceeding. The time needed in order to record a pH shift can be assumed as a delay time proportional to the recalcitrancy of a compound. 

The pH of the colon varies depending on the type of food ingested. In general, a drop in pH to 5.5 6.5 is monitored when a radiotelemetric capsule enters the colon [85,86]. This pH drop is caused by acidification of the colonic contents by bacterial fermentation (Table 1.1). 

Common adverse psychologic consequences of hallucinogenic drugs include panic reactions ("bad trips") and acute psychotic reactions with PCP. Treatment includes benzodiazepines for sedation and constant monitoring by a nondrugged companion for several hours. Acidification of the urine (see Chapter 59 Management of the Poisoned Patient) may hasten PCP excretion. 

The present route to conjugated diynes is the method of choice if the corresponding skipped diyne or allene is available.2-6 With naturally occurring polyynes this is often the case. Depending on the 1,4-diyne, the base-catalyzed isomerization may be successfully stopped (by acidification) to yield the intermediate allenylacetylene. Since the isolation of the allene may or may not be desired, it seems prudent to monitor the progress of isomerization of new 1,4-diynes, e.g., by n.m.r., and establish the approximate lifetimes of transient species. In this way some allenes as well as conjugated diynes may be obtained.6... 

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