In the present work, aqua regia followed by solid phase extraction using activated carbon was developed for soil sample treatment.
The analytical approach was further integrated with machine learning algorithms enabling the prediction of gold potential zone.
Some modifications such as roasting the samples and hydrofluoric acid addition for silicon structure removal of the samples have also been investigated.
The analytical performance of the method was evaluated via certified reference materials and geological samples, at different concentration levels.
Comparison of responses obtained for the analysis of 40 different geological samples via fire assay and aqua regia digestion shows a good compatibility which verified the aqua regia as a simple, low cost and reliable treatment technique.
In the present work, aqua regia followed by solid phase extraction using activated carbon was developed for soil sample treatment. The analytical approach was further integrated with machine learning algorithms enabling the prediction of gold potential zone. Some modifications such as roasting the samples and hydrofluoric acid addition for silicon structure removal of the samples have also been investigated. The analytical performance of the method was evaluated via certified reference materials and geological samples, at different concentration levels. Random Forest, Gaussian Process Regression and Ordinary Kriging models were subsequently used considering nonlinear spatial relationships, uncertainty prediction and generate predictive gold distribution map. Despite the significant effect of sample roasting, HF addition had only a minor and negligible effect (according to t-test at 95% confidence level) and the proposed method was able to detect gold concentrations ranging from 18.0 ng/g to 53,000 ng/g in soil samples and down to 0.01 µg/mL in aqueous samples with correlation coefficients greater than 0.9991. The method accuracy and precision were in the range of 3.7–9.6 and − 9.5-+7.4, respectively. Comparison of responses obtained for the analysis of 40 different geological samples via fire assay and aqua regia digestion shows a good compatibility which verified the aqua regia as a simple, low cost and reliable treatment technique.
