Phenol capillary absorption

Osmotic balance across the plasma membrane is regulated by the concentration of proteins (albumin more than globulins). Relative dehydration would increase plasma oncotic pressure and capillary absorption of water and water-soluble molecules. Phenol is soluble in water, and its absorption rate could be accelerated by the slightest dehydration. 

Kahn, H. L., Peterson, G. E., and Sohallis, J. E., Atomic absorption microsampling with the sampling boat technique. At. Absorption Newslett. 7, 35-39 (1968). Karoum, F., and Sandler, M., High resolution gas chromatographic anal3rsis of phenolic acids and alcohols using capillary columns. Clin. Chim. Acta 32, 391-397 (1971). 

Figure 33-1 5 Typical separation by MECC. (a) Some test compounds 1 = methanol, 2 = resorcinol, 3 = phenol, 4 = p-nitroaniline, 5 = nitrobenzene, 6 = toluene, 7 = 2-naphthol, 8 = Sudan III capillary, 50-p.m inside diameter, 500 mm to the detector applied voltage, ca. 15 kV detection UV absorption at 210 nm. (b) Analysis of a cold medicine 1 = acetaminophen, 2 = caffeine, 3 = sulpyrine, 4 = naproxen, 5 = guaiphenesin, 10 = noscapine, 11 = chloropheniramine and tipepidine applied voltage, 20 kV capillary, as in (a) detection UV absorption at 220 nm. (From S. Terabe, Trends Anal. Client., 1989,8, 129.)...

Many metabolites both ionizable and nonionizable can be measured by different forms of CE such as CZE, MEKC, and chirality. Metabolites with strong UV absorption such as nucleotides, phenolic amino acids, and their metabolites are easy to measure by CE. However, some of these require concentration and clean up before the CE step [5]. This can be achieved by traditional concentrating methods, such as solid phase and solvent extraction or by concentration on the capillary (stacking). Examples of small molecules that have been analyzed by CE are nucleotides [79,80], amino acids, catecholamines [81-83], and sugars [84,85]. Below is a more detailed discussion of some of these compounds. 

For more complex samples with a number of electroactive species to be determined, separation by HPLC, or other methods such as ion chromatography or capillary electrophoresis, followed by coulometric detection is better suited. Its applications in HPLC are usually to oxidizable organic species that cannot be determined by ultraviolet absorption, the standard detection technique in HPLC. Examples for such species include amines and phenols, catecholamines (such as the neurotransmitters adrenaline and... 

Capillary electrophoresis (CE) is a good alternative to GC and LC techniques for profile determination of OL derivatives. CE requires minimal sample preparatiOTi and represents a good compromise between analysis time and satisfactory characterization. The most efficient operative mode to separate phenolic compounds is the borate-based CE, which makes use of a borate run buffer at alkaline pH [52], To date, the most widely used detector in CE is based on UV absorption [53, 54], although the coupling to MS analyzers such as QqQ, IT, TOF has revalorized the potential of this technique [55]. 

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