Trapping organic materials

In this method volatile organic matter in seawater is concentrated on a Tenax GC solid adsorbent trap and dry-ice trap in series. The trapped organic material is then desorbed and oxidised to carbon dioxide, which is measured with a non-dispersive infrared analyser. A dynamic headspace method was used for the extraction with the assistance of nitrogen purging. Dynamic headspace analysis [184] is an efficient extraction procedure. The efficiency of extraction... 

Fig. 4.19 is a cross-section the actual micelle structure is three-dimensional. The assembled structure is completely nonregular rapid exchange between micelle molecules and monomeric soluble molecules occurs. Therefore, a micelle can be regarded as a disordered dynamic supramolecular assembly. In a micellar structure, the hydrophilic part of the component molecule is located on the outer surface of the micelle, in contact with the aqueous phase, which minimizes the unfavorable contact of the hydrophobic part with water. Micelles can trap organic materials hke oils in the inner hydrophobic core, so micelle formation is used in many cleaning agents. 

Seven coals were used in this study (Table I). To remove trapped organic materials (21, 29), all coal samples were extracted with benzene-methanol (3 1 refluxing for 48 hr) and 2.5% aqueous NaOH (20°-35°C for 16 hr) before oxidation. 

All samples were pretreated to remove solvent-extractable trapped organic materials and were dried at 110°-120°C for 16-18 hr under vacuum before oxidation. 

Adjusting the Analyte s Concentration Analytes present at concentrations too small to give an adequate signal need to be concentrated before analyzing. A side benefit of many of the extraction methods outlined earlier is that they often concentrate the analytes. Volatile organic materials isolated from aqueous samples by a purge and trap, for example, can be concentrated by as much as 1000-fold. 

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