Now that field collection is finished, the next stage of ZANBA can enter full swing – strontium extraction and analysis. The high level of organic material in the plant samples makes extracting the strontium a long process – longer than extracting it from the human or animal teeth that are often the target of archaeological strontium studies. The samples first have to sit in concentrated nitric acid to begin digesting the organic materials. After the nitric acid has fully reacted with the samples, I add a strong hydrogen peroxide solution to continue the digestion process. The process involves a lot of waiting – it can take more than a week for the chemicals to finish reacting with the samples.
The processing takes place in a clean lab under a fume hood, so the number of samples that can be digested at any one time is limited by space, supplies, and the other researchers who need to use the lab. Getting through all 126 samples is going to be a challenge!