Urine Samples

Question 0

Explain the process of testing for anabolic steroids

Answer 0

• a urine sample is analysed using gas chromatography or mass spectroscopy
• in gas chromatography a substance is vaporised in the presence of a gaseous solvent
• it is passed down a long thing tube coated with an adsorption agent
• different substance stay dissolved in the the gas for different periods of time (retention time) and reaves different distances down the tube
• when the substance is no longer dissolved it will adsorb to the side of the tube which contains the adsorption agent
• this is then analysed to create a chromatogram which is compared and analysed to know values for different substances

Question 1

Explain the process of pregnancy testing

Answer 1

• once implanted in the uterine lining, a human embryo starts secreting a pregnancy hormone called human chorionic gonadotrophin (hCG)
• a pregnancy test will test for hCG
• antibodies on the pregnancy test will have a complementary shape to the hCG
• hCG will bind to the antibody
• the antibody has a coloured bead attached to it
• it forms a hCG-antibody complex which moves up the strip until it stick so a band of immobilised antibodies
• as a result all the antibodies carrying a coloured bead and attached to hCG are held in one place forming a coloured line
• there is always one control coloured line to use for comparison and a second coloured line indicates pregnancy