Acid test (gold) mark is tested by applying aqua fortis (nitric acid), which dissolves the mark of any item that is not gold. If the mark remains, it is tested by applying aqua regia (nitric acid and hydrochloric acid). If the mark is removed, then this test dissolves the gold, proving the item to be genuine gold. More accurate testing of the item for its fineness or purity can be done through the use of differing strengths of aqua regia and comparative testing of gold items of known fineness. The figurative meaning of the expression, where it is applied to tests of character,
Trifluoroacetic acid causes severe skin burns and is toxic for aquatic organisms even at low concentrations. TFA's reaction with bases and metals, especially light metals, is strongly exothermic. The reaction with lithium aluminium hydride (LAH) results in an explosion. TFA is not biodegradable and is somewhat toxic to aquatic life - although it does not bioaccumulate, prevention of release into waterways is of extreme importance when using TFA Trifluoroacetic acid Trifluoroacetic acid (TFA) is an organofluorine compound with the chemical formula CFCOH. It is a structural analogue of acetic acid with all three of the acetyl group’s hydrogen atoms replaced by fluorine