DNA Presumptive Testing

• DNA Presumptive Testing


  Gives indication
• Substances tested


  • Blood
  • Saliva
  • Semen
  • Clothing
• Kastle Mayer Test


  1. Phenolphthalein added

  2. Catalyses reaction

  3. Produces pink colour
• Leomalachite Green/Luminol Reagent


  • Catalyses reaction with hydrogen peroxide
  • Produces green/blue result
• OBT (Ortho-tolidine) Test


  1. Sample added to transport medium

  2. Solution added to test strip

  3. Produces green result in 2-3 mins
• Luminol Test


  1. Spray reacts with hematin in blood stains

  2. Produces blue fluorescence under UV light

  3. Lasts for a few minutes
• Luminol test dilutes DNA
• Luminol test can give false positives for cleaning products
• Hemastix


  • Blood reagent on test strip
  • Detects peroxidase activity and haemoglobin
• Phadebas Test


  1. Paper and solution reacts with amylase

  2. Produces blue result
• Phosphatase Test


  • Tests for enzyme found in semen and prostate gland
  • Enzymatic breakdown of sodium a-napthyl phosphate/Brentamine
  • Produces dark purple result