High levels of glucose, albumin, ascorbic acid, tetracycline or cephalexin, or large amounts of oxalic acid, may inhibit the reaction and lead to false-negative results. Vaginal contamination can ...

The acid has dissolved both the 10k and 14k samples. The unknown metal is therefore 14-karat or slightly higher. Always prepare the touchstone for its next use by cleaning it thoroughly. Remove the ...