: mtb s t : -myp R e ! i
v\t s re : : : o : : -
: moo r T - ■ o
mt)o v r : : : o : : . wes r p :MO|ß|ßSlg;i^p_r|fmyp_s_r J|M.:.:. hqq-kf 9. .T... p
. ¡mmfltfi r t ° : oo~ ■ i ■ 1
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(denoted by an R_T), and raw and treated soil, and vegetation-derived organic matter (denoted by an S_R, S_T and V_R, V_T, respectively) tend to score higher than all the alum flocculated material and raw reservoir-derived organic matter. Differences in the relative ratios of nondiagnostic pyrolysis products (such as alkylbenzene and alkylphenol derivatives) account for the bulk of the variance described by this method. Most of the samples scored about 0.1 for principal component two. Soil-derived organic matter samples and most alum-flocculated materials score highly in components one and two because of the relatively high proportion of aromatic material, much of which is probably derived from secondary pyrolysis reactions.
The described Py-GC/MS analysis techniques have some limitations for the analysis of whole samples. The main limitation is the formation of isobaric and isomeric ions with a given integer mass to charge (m/z) ratio, which presents the assignment of an ion structure to a particular m/z ratio in a complex mass spectrum. The observation of apeak in a spectrum is thus not conclusive evidence for the presence of a particular pyrolysis product. For this reason it is important to utilize standard materials. Pattern recognition and multivariate analysis procedures have been also developed to specifically deal with this problem. These methods involve computer programs for "cluster analysis" which identifies groups of ions of common origin. Observation of these groups of ions then allows identification of a compound or type of compound with a greater degree of confidence.
The range of organic matter which can be analyzed by Py-GC/MS is extensive and due to the small samples required and minimal preparation, analytical pyrolysis is specially well suited to analyze environmental samples (Table 8.2).
Examples of analytical pyrolysis of organic matter from water, soils, air, and waste are further discussed below.
The cost associated with the removal of organic matter is one of the major cost elements associated with treating water for drinking purposes. The flocculation and filtration processes easily remove
Applications of Py-GC/MS Used to Study Organic Matter from Environmental Samples
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