Toxic similarity matrices

Steps 4 and 5 are not straightforward activities, especially when it comes to long-term effects, i.e. the development of occupational diseases. For accidental exposures to acute toxic/corrosive chemicals, the risk-estimation matrix of Table 22.5 can be used. A similar matrix for use with other chemical exposure assessments is shown in Table 23.2. The application of it involves a number of crucial decisions concerning ... 

Identification and quantification is obtained by combined high-resolution gas chromatography/mass spectrometry (GC/MS) methods after special cleanup procedures of the matrix, as shown later for sediments (see Figure 8.2). The cleanup methods for other matrices are similar. Quantification is obtained by addition of 13-C labeled standards before the cleanup procedure. In general, only the toxic isomers are identified and quantified. 

Plasma is the main biological sample used in clinical and toxicological analysis, as concentrations found in this matrix are correlated to the pharmacological effect, as well as to the side and toxic effects. However, oral fluid has also been employed in some specific applications because of the advantages associated to this alternative specimen easy, painless, and noninvasive collection, which does not require qualified personnel, it represents the free analyte fraction, and it has a window of detection similar to that in plasma. Within the possible applications of oral fluid analysis, two are of special relevance ... 

Typical questions related to the compound are whether the toxicity data that are available match with the situation that is being investigated, both regarding the test matrix and the assessed matrix (physicochemical processes determining availability), and regarding the species that were tested and the typical species for the assessed situation (biotic similarity). 

Peptide antibiotics are composed of the peptide chain of amino acids, d and l, covalently linked to other moieties. Most peptides are toxic and are poorly absorbed from the alimentary tract. Peptide antibiotics are difficult to analyze in biological and food samples, as they are similar to matrix components. They can be separated on silica gel, amino silica gel, and silanized silica gel plates. A variety of mobile phases are applied, from a simple one like chloroform-methanol to a multicomponent one like n-butanol-butyl acetate-... 

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