Blood collection tubes are made of glass or plastic, with specific additives (such as anticoagulants, coagulants, separating gels, etc.) pre-added inside to maintain the stability of blood components. Different colors are used to distinguish their purposes, for example:
Purple tube (EDTA anticoagulant): used for blood routine examination, blood typing, etc;
Green tube (heparin anticoagulant): suitable for biochemical and immunological testing;
Blue tube (sodium citrate anticoagulant): specifically used for coagulation function testing;
Grey tube (sodium fluoride/potassium oxalate): for the detection of metabolites such as blood glucose and lactic acid;
Red tube (no additives or coagulants): used for biochemical and immunological testing after serum separation.
The additive ratio of each type of blood collection tube is strictly calibrated and needs to be selected according to the testing items to avoid cross-contamination or result deviation.