The serum from these tubes can be used for most biochemistry tests , hormone tests , infectious disease antibody serology and mineral analysis . These tubes are not ideal for toxicological analysis or drugmonitoring purposes because the gel can absorb lipophilic substances ( some drugs ). These serum separator gel tubes should not be used to transport body fluids destined for cytological analysis .
C . EDTA Tubes ( Lavender stopper ) These tubes contain potassium or sodium salts of ethylenediamine tetra-acetic acid which chelates calcium and prevents clotting . The tubes must be adequately filled to achieve the correct ratio of anticoagulant to blood , to ensure samples do not clot . Gently invert the tubes up and down a few times to mix blood with anti-coagulants .
EDTA tubes are used for haematology samples , nucleic acid amplification ( PCR ), other genetic analyses , blood selenium analysis and lead determination . They are also the preferred sample receptacle for cytology fluid samples , because they preserve cell morphology .
Blood samples collected into EDTA should not be frozen . When shipping wrap these tubes in tissue paper or bubble-wrap so that they do not come into direct contact with ice packs which can cause haemolysis . Samples should be transported chilled at 4-12 ° C .
D . Citrate Tubes ( Light Blue stopper ) These tubes contain sodium citrate to prevent clotting and tubes must be filled to the correct level ( usually indicated on the tube ). After blood collection tubes should be inverted 4 – 5 times to adequately mix the blood and citrate . These tubes are used for the clotting
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