CC100 Lecture Notes - Lecture 5: Chemical Database, Chemiluminescence, Prostate
Document Summary
Presumptive test: a cheap and quick test to determine the possible presence of a substance. Limitations to presumptive tests: false positives - interference, e. g. bleach or copper salts for luminol, codeine for heroine, false negatives. Interference, e. g. ascorbic acid for blood: below detection limit. Kastle-meyer test: the following is added subsequently, ethanol, phenolphthalein, wait and then, hydrogen peroxide, turns pink in few seconds, non-destructive, dna analysis can be performed afterwards. Interferences: plant enzymes (horseradish, potatoes) false positives, blood can mask colour change, acid solutions can inhibit the reaction false negatives. Leuco-malachite green (lmg: same as km test, except for the use of lmg as the indicator, blue-green indicated possible presence of blood. Luminol/bluestar tests: chemi-luminescence, luminol needs darkened room. Bluestartm can be used without complete darkness: can detect 1:100,000 dilution, do not interfere with subsequent dna testing. Is the material collected from the crime scene the suspect"s blood: dna is not a confirmatory technique for blood!
