Which of the following is found in purple top tubes used for blood collection for DNA analysis?
Ethylenediaminetetraacetic acid
Sodium heparin
Sodium fluoride
Sodium citrate
Silicon coated tube
Show Answer and Explanations
Ethylenediaminetetraacetic acid — Correct answer
Correct. EDTA is in purple top tubes and is used for DNA collection.
Sodium heparin
Incorrect. Green top tubes contain heparin. They are used for chromosome analysis and chemistry tests such as carboxyhemoglobin and ammonia, that don't depend on clotting factors.
Sodium fluoride
Incorrect. Gray top tubes contain fluoride and potassium oxalate. Fluoride inhibits glycolysis, making it useful for tests of blood glucose and lactic acid. The oxalate binds calcium and acts as an anticoagulant. Gray top tubes are useful for alcohol and drug testing.
Sodium citrate
Incorrect. Citrate is an anticoagulant used in the light blue top tube, for coagulation studies.
Silicon coated tube
Incorrect. The red top tube is coated with silicon. It is useful for serum chemistry tests such as potassium, ABO typing, and serology (antibody identification).
Summary
Summary: EDTA is used for DNA collection. Citrate is used for coagulation studies. Fluoride is used for glucose and lactate studies.