Chlorinated humic acid, determination

Becker et al. [2] have discussed the application of size exclusion chromatography to the determination of chlorinated humic acids in potable waters. 

Gas chromatography has also been applied to the determination of the following types of organic compounds in potable waters (see Table 15.11) aliphatic hydrocarbons, phenols, nitrophenols, chlorinated dioxins, anticholisterinase insecticides, chlorinated humic acid and chlorolignosulphonic acids. 

The type of activated carbon used for the treatment of groundwater depends upon the other organic compounds present. For example, humic acids will often compete with other contaminants for adsorption sites. Hence, for each situation, isotherms should be determined, and the efficiency of contaminant removal should be evaluated on a TOC basis (total organic carbon). As noted, the compounds most prevalent in groundwaters are chlorinated organics. Their removal by adsorption on GAC is the most effective treatment in liquid or gas phase processes [66]. 

Selective extraction was used to operationally determine the quantitative and qualitative distributions of PCB 8 and saturated hydrocarbons among free lipid (FL), humic acid (HA), and humin (HU) fractions of four contaminated estuarine sediments. In all samples, over 90% of the total sedimentary PCB s and hydrocarbons were extracted with FL fractions. Bound (HA and HD) and free assemblages of these compounds may have derived from different sources. Two polar, chlorinated pollutants also detected In this study, hexachlorophene (HCP) and pentachlorophenol (PCP), were proportionately more concentrated In bound fractions than the non-polar compounds HCP was detected only In HA fractions and was probably chemically hound to refractory organic matter. Selective extraction Is a promising technique for Investigating strongly bound polar pollutants, such as HCP, which apparently are not recovered by conventional solvent extraction. 

Japenga et al. [56] determined polychlorinated biphenyls and chlorinated insecticides in River Elbe estuary sediments by a procedure in which the sediments were pretreated with acetic acid, mixed with silica and Soxhlet-extracted with benzene/hexane. Humic material and elemental sulphur were removed by passing the extract through a chromatographic column containing basic alumina, on which sodium sulphite and sodium hydroxide were adsorbed. Silica fractionation was followed by gas chromatography to analyse chlorinated pesticides, polychlorinated biphenyls and polyaromatic hydrocarbons. Recovery experiments with standard solutions gave recoveries of 90-102%. 

The American Water Work Association (AWWA) and US ERA developed a number of methods for phenol determination . ERA Method 528 is dedicated to the determination of phenols in drinking water by solid-phase extraction and GC/MS analysis and is developed for 12 phenols, mainly chlorophenols, nitro- and methyl-substituted phenols . Unfortunately, users have to take into account that the recommended internal standard tetrachlorophenol can also be found in water samples and has to be used with precaution or, better, substituted with another compound. The same problem applies in the case of the recommended surrogate 2,4,6-tribromophenol, which cannot be used in the analysis of water in areas with high bromine ion content. (Some examples of tribromophenol formation by humic or fulvic acid chlorination was mentioned by Richardson °°.)... 

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