Induced current method absorption

Contrary to potentiometric methods that operate under null current conditions, other electrochemical methods impose an external energy source on the sample to induce chemical reactions that would not otherwise spontaneously occur. It is thus possible to measure all sorts of ions and organic compounds that can either be reduced or oxidised electrochemically. Polarography, the best known of voltammetric methods, is still a competitive technique for certain determinations, even though it is outclassed in its present form. It is sometimes an alternative to atomic absorption methods. A second group of methods, such as coulometry, is based on constant current. Electrochemical sensors and their use as chromatographic detectors open new areas of application for this arsenal of techniques. 

The direct accurate measurement of local OH concentrations has been one of the major technical challenges in atmospheric chemistry since the early 1980s. This goal was first achieved in the stratosphere (e.g., Stimpfle and Anderson, 1988), but the troposphere proved more difficult (Crosley, 1995). Nevertheless, early long-baseline absorption methods for OH were adequate to test some basic theory (e.g., Poppe et al., 1994). Current successful direct methods include differential optical absorption near-UV spectroscopy with long baselines (e.g., Mount, 1992 Dorn et al, 1995 Brandenburger et al., 1998), laser-induced fluorescence after expansion of air samples (e.g., Hard et al., 1984, >1995 Holland et al., 1995), and a variety of chemical conversion techniques (Felton et al, 1990 Chen and Mopper, 2000 Tanner et al., 1997). 

Currently, ultraviolet (UV) irradiation is the most widely used physical inactivation method." UV light induces damage at the genomic level of cells, mainly due to the fact that absorption is much stronger in DNA compared to proteins and other biological molecules." ... 

The most common analytical methods that can sensitively measure manganese include neutron activation analysis, X-ray fluorescence, proton-induced X-ray emission, inductively coupled plasma emission, EPR, and flameless atomic absorption spectrophotometry (AAS). Currently, the most common method employed is flameless AAS. All of these methods, with the exception of EPR, measure the total concentration of manganese in the samples. EPR allows selective measurement of bound versus free manganese. 

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