Answer to Question 1
Oxygen normally combines with hemoglobin, which transports the oxygen throughout the body. However, carbon monoxide in the bloodstream also combines with hemoglobin, reducing the amount of hemoglobin left to carry oxygen. If enough hemoglobin combines with carbon monoxide, not enough is left to carry sufficient oxygen to the tissues, and death by asphyxiation follows.
Answer to Question 2
The three most widely used screening tests are thin-layer chromatography (TLC), gas chromatography (GC), and immunoassay. Gas chromatography/mass spectrometry is generally accepted as the confirmation test of choice.