ABSTRACT
This chapter reviews the physical and chemical characteristics of various types of organic materials collected primarily from archaeological contexts, as considered in terms of their suitability and reliability as samples for 14C dating purposes. In considering sample types, there is one issue that is often immediately raised when a given 14C determination fails to confirm the opinions, understandings, assumptions, and deeply held commitments of interested parties. This is the nature and effects of sample contamination. Samples are three types: Standard Samples, Nonstandard Samples and Problematic Samples. The primary purpose of sample pretreatment is to remove any carbon-containing compound in a sample matrix that might exhibit 14C activities different from that of the autochthonic or indigenous carbon contained in the sample material. Major contaminant types are grouped into five broad categories: physically removable, acid-soluble, base-soluble, solvent-soluble, and molecular component separations. Each category of sample-specific strategies and techniques developed to facilitate the removal of actual or presumed non-indigenous carbon from sample materials.
