Final answer:
The light green tube in clinical tests typically contains lithium heparin and pertains to chemistry tests. If both anti-A and anti-B antibodies cause agglutination, the blood type is AB. Other methods like using EDTA tubes or plasma pretreatment are for specific drug testing.
Step-by-step explanation:
The light green tube in a clinical setting typically contains the anticoagulant lithium heparin which is used for plasma determinations in chemistry tests. When blood is collected into these tubes, they are centrifuged to obtain plasma. Lithium heparin acts as an anticoagulant by inhibiting thrombin and is used in chemistry lab sections. In the context of a patient having blood drawn for a type and screen before surgery, visible agglutination in both wells containing anti-A and anti-B antibodies indicates that the patient's blood type is AB positive, presuming no error was made. This is because the presence of both types of antibodies causes clumping (agglutination) in the presence of both A and B antigens present on the red blood cells of someone with AB type blood.
In the specific scenarios provided, blood samples were also prepared using different methods depending on the tests to be run, involving anticoagulants such as EDTA and treatments like plasma pretreatment by SPE cation-exchange or PP with ACN containing internal standards (IS) such as isoniazid or lamivudine for specific drug testing procedures.