Biological matrices characteristics

Recognising that aU analytical results represent estimates of the concentration of an analyte within a food/biological matrix, the most important characteristic of any result is a statement of its uncertainty interval. Typically, the repeatability of an analysis performed on a particular... 

Method precision (random error, variation) and accuracy (systematic error, mean bias) for LBAs should be evaluated by analyzing validation samples (QC samples) that are prepared in a biological matrix that is judged scientifically to be representative of the anticipated study samples [18]. This topic has been reviewed in other publications [3 6,9,10,20]. These performance characteristics should be evaluated during the method development phase, taking into consideration the factors known to vary in the method (e.g., analysts, instruments, reagents, different days, etc.). Several concentrations are required during the method development phase and are assayed in replicates. Factors known to vary between runs (e.g., analyst, instrument, and day)... 

Molecular fossils have been successfully identified in younger Precambrian rocks and linked to certain classes of biological source material. In organic analyses of ancient sediments the cleaned, pulverized rocks are treated with organic solvents to extract a soluble fraction containing the less complex and more easily identifiable compounds. However, this fraction is more subject to contamination since it is not locked within the rock matrix. Normal alkanes have been identified in extracts of the 3 billion year old Fig Tree Shale. These alkanes have a probable biological origin in cellular lipids. The odd and even-numbered alkanes are evenly distributed, a characteristic of alkanes from ancient rocks. It is uncertain, however, whether these compounds were present at the time of deposition or derived from a later source [24]. 

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