Tissues, analytical method development

Early analytical methods developed to assay heroin and its metabolites in biological fluids and tissues utilized indicator-dye, paper chromatography (PC), and TLC techniques. Indicator-dye techniques, based upon the reaction of organic bases with colored organic acids such as methyl orange to form complexes soluble in organic solvents, were used to quantify heroin and metabolites. The colored complexes were subsequently measured by spectrophotometry. 

Extremely sensitive analytical methods have been developed for the detection of heptachlor and heptachlor epoxide in various environmental and biological samples (detection limits as low as 10 ng/L). Although most methods were developed for detecting heptachlor and heptachlor epoxide in environmental media, the technology is readily adaptable to biological materials including breast milk, adipose tissue, and serum. These methods can be used to determine whether exposure has occurred. The presence of heptachlor may reflect an exposure to heptachlor or chlordane because it is a metabolite of chlordane. The presence of heptachlor epoxide may reflect an exposure to heptachlor or to chlordane since it is a metabolite of both these pesticides. However, in the absence of stable chlordane residues (e.g., nonachlor and oxychlordane), the heptachlor epoxide would most likely have been derived from heptachlor. 

Methods for Determining Biomarkers of Exposure and Effect. Exposure to 1,4-dichloro-benzene may be evaluated by measuring the levels of this compound in blood, breath, milk, and adipose tissue, and by measuring the level of 2,5-dichlorophenol, a metabolite of 1,4-dichlorobenzene, in urine (Bristol et al. 1982 Erickson et al. 1980 Jan 1983 Langhorst and Nestrick 1979 Pellizzari et al. 1985). Sensitive analytical methods are available for measurements in blood. Development of methods with improved specificity and sensitivity for other tissues and breath would be valuable in identifying individuals with low-level exposure. Development of standardized procedures would permit comparison of data and facilitate the study of correlations between exposure and measured levels biological samples. Interlaboratory studies are also needed to provide better performance data for methods currently in use. 

The compounds analyzed by GC/MS comprise e.g. amino acids [34, 39, 64 - 69], organic acids [33,63,65,66,69], sugars [39,70,71 ], lipids and fatty acids [72, 73]. Moreover, mass distributions of polymers and their building blocks, obtained via hydrolysis of the polymer, were assessed. Examples are glycogen [39, 70], cell protein [8,10,17], or DNA [74]. Most of the analytical methods have been developed for tissue samples. Since most of the compounds studied are polar or even charged molecules, derivatization is necessary in most of the cases of GC/MS analysis. The derivatization method of choice clearly depends... 

Methods for the detemination of organobromine compounds such as PBBs and PBDEs generally consist of the following steps extraction of the analyte from the sample matrix clean-up to remove interfering compounds and analysis (separation and quantitation). The primary method of analysis is GC coupled with ECD or MS. Analytical methods have been developed for the determination of PBBs and PBDEs in blood or serum, urine, feces, adipose tissue, liver, and breast milk. The methods for determining PBB and PBDE residues in biological samples are given in Tables 7-1 and 7-2, respectively. 

Generation of potential human metabolites for structural identification prior to administration of the drug candidate to humans can be performed with either cDNA-expressed enzymes or tissue fractions. This allows identification of potential human metabolites and development of appropriate analytical methods prior to clinical trials. Generation and identification of pharmacologically active human metabolites early in the development process can be beneficial for obtaining appropriate patent protection. 

As rocks are transformed to soil so a proportion of each element is usually converted to a form which plant roots can absorb. Consequently, most of the elements in the Periodic Table would probably be detected in any plant sample if sufficiently sensitive analytical methods were used. Uptake of an element is no evidence that it plays any role in the development of the plant since a root has no power to reject any soluble element entirely. One must therefore differentiate between those elements which are needed, the essential nutrients, and the rest. The conventional criteria by which the presence of an element is regarded as essential rather than adventitious are these the plant cannot complete its life cycle in the absence of the element the action of the element must be specific in that no other element can wholly substitute for it nor is the element simply involved in beneficially altering the plants root environment the element must be shown to be a constituent of an essential metabolite, or required for the proper functioning of an essential enzyme system or be uniquely involved in maintaining the overall ionic composition of tissue. Table 1-2 lists the elements which are generally accepted as being essential for plants. Major or macronutrients are separated from micronutrients, the latter being present in tissue concentration < 0.1 %. 

No analytical methods specifically used for the determination of tetryl in biological fluids and tissues were located. One attempt to develop a method for detecting tetryl in animal tissues using high-performance liquid chromatography (HPLC) with ultraviolet (UV) detection was unsuccessful because of suspected metabolism and binding of the parent compound and/or metabolites to macromolecules (Army 1981a). However, methods were located for the detection of the tetryl metabolites, picric acid and picramic acid, in urine and for the analysis of tetryl in hand swabs. Table 6-1 is a summary of methods used to determine tetryl metabolites in urine and tetryl in hand swabs. 

Analytical methods have been developed to measure benzene levels in exhaled breath, blood, and various body tissues. The primary method of analyzing for benzene in exhaled breath, body fluids and tissues is gas chromatography (GC) coupled with either flame ionization detection (FID), photoionization detection (PID), or mass spectrometry (MS). Rigorous sample collection and preparation methods must be followed when analyzing for benzene to prevent contamination of the sample. A summary of commonly used methods of measuring benzene in biological samples is presented in Table 6-1. 

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