Date on Master's Thesis/Doctoral Dissertation
Rypkema, Heather A.
Archaeological chemistry; Phosphates--Research
Archaeologists use soil analysis to detect chemicals, like phosphate, to indicate areas of anthropogenic activity. Phosphate detection is a multi-step process, which makes standard techniques time consuming. Kinetic studies decreased the analysis time for the malachite green (MG) method of phosphate detection. The 3-minute method allows extraction and analysis to be complete in 15 minutes. Continued studies resulted in two-color spectral monitoring, which provided values instantaneously. Arsenate (As(V)) interfere with the MG method and results in overestimation of phosphate. As(V) must be reduced to non-interfering arsenite. Two As(V) reducing agents--L-Cysteine and thiosulfate--were investigated. The thiosulfate method was suitable for field implementation with the 3-minute malachite green method. L-Cysteine is compatible with both MG time scales, but pre-reduction could not be improved beyond 20 minutes. The 3-minute malachite green method was utilized at an archaeological site in Virginia. The survey led to delineation of the site boundaries.
DeNeve, Laura A., "Soil phosphate detection and archaeology : in-stride phosphate detection and the elimination of arsenate interference to the malachite green method." (2007). Electronic Theses and Dissertations. Paper 331.