Mobile phase microbial contamination

When contamination collects on a column, poor peak shapes (usually tailing) and extraneous peaks will appear with an increase in backpressure. Therefore, samples should always be filtered before injection. Mobile phases should be filtered a few days after preparation to remove any particles and prevent microbial... 

Some mobile phases are prone to microbial contamination. Acetate buffers are particularly susceptible. This may not be a significant problem if the mobile phase is stored at a low temperature and then heated in a column heater however, if the buffer is stored for a few hours at 25°C or above, it may be altered as a result of microbial growth. 

The distribution between the aqueous (mobile) phase and the various sediment or soil (stationary) phases is one of the key parameters determining both transport and transformation of contaminants in subsurface systems. While the impact of adsorp-tion/desorption processes on subsurface transport is obvious and has been the subject of numerous investigations, their effects on transformation reactions of organic contaminants has been widely ignored in the past. It is important to realize that both the extent and the type of distribution of a contaminant between aqueous and solid phase(s) may determine its availability as well as its reactivity towards abiotic and microbial transformation reactions. For instance, it has been shown for a series of / ar -substituted n-alkyl-nitrobenzenes that the abiotic reduction of these compounds in natural sediments is strongly affected by the... 

Electric fields use in soil restoration has been focused on contaminant extraction by their transport under electroosmosis and ionic migration. Contaminant extraction by electric fields is a successful technique for removal of ionic or mobile contaminants in the subsurface. However, this technique might not be effective in treatment of soils contaminated with immobile and/or trapped organics, such as dense non aqueous phase liquids (DNAPLs). For such organics, it is possible to use electric fields to stimulate in situ biodegradation under either aerobic or anaerobic conditions. It is necessary to evaluate the impact of dc electric fields on the biogeochemical interactions prior to application of the technique. It is not clear yet how dc electric fields will impact microbial adhesion and transport in the subsurface. Further, the effect of dc fields on the activity of microorganisms in a soil matrix is not yet well understood. 

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