All of the following are screening tests for blood except

Crystal Tests Crystal tests are regarded as confirmatory tests. These tests involve the non-protein heme group of hemoglobin, called porphyrins. Haemochromogen Crystal Test (Takayama test): Place a small piece of suspected material on a glass slide and add 2 to 3 drops of Takayama reagent (sodium hydroxide, pyridine, glucose), and cover with a coverslip. Pink, feathery crystals of haemochromogen or reduced alkaline haematin arranged in clusters, sheaves, etc., appear in one to six minutes. Slight warming of the slide hastens the reaction. The result is negative if crystals are not formed in 30 minutes. The test gives good result even with old stains. It is delicate and more reliable. Ref:- k s narayan reddy; pg num:-451, image plate 12