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A New Method for Extracting Silver from Animal Tissue

Ryan T. Reynolds, Robert J. Taylor, and Gerald R. Bratton

Trace Elements Research Laboratory, College of Veterinary Medicine, Texas A&M University, College Station, TX, USA


Objective- A potentially toxic metal sometimes present in animal tissue is silver. Previous tissue digestion methods for recovering silver for analysis have been shown to be inadequate (Christopher, 2002, 2004; Daskalakis, et al., 1997).  A new method using nitric acid, hydrochloric acid, hydrogen peroxide, and a heat source has been shown, in limited use, to be more effective.  We seek to determine 1) if this effectiveness is reproducible; if so, 2) optimum effective conditions; 3) validity for high and low level silver tissues. 

Animals or Sample Population – Whole, homogenized Beluga and Bowhead whale livers.

Procedure - Organic matter is digested and then analyzed with a mass spectrometer.  Variables include 1) using dry versus wet tissue; 2) heat source; 3) acid ratios; 4) heating time.      

Results – Dry tissue showed greater precision than wet tissue.  For high silver tissue, the open microwave and oven seemed to be the most precise; for low silver tissue, the closed microwave appeared to be the most precise.  For high and low silver tissues, all heating sources gave values within reasonable precision limits.  The method appeared to be accurate for low silver tissue; for high silver tissue, more data is needed.  Optimum acid ratio and heating length data is not yet available. 

Conclusions and Clinical Relevance – The method continues to show promise, but more work is needed before any conclusions can be drawn with any reasonable degree of certainty.  If the method is validated in the end, it will provide analysts with a valuable tool for monitoring the health of animals and the humans that use their products.