Test materials

The right choice of test material for each clinical situation and correct method of sample collection are an essential part of the preanalytical procedures in medical practices.

Blood tests

Whole blood, plasma and serum


A distinction is made between whole blood, plasma and serum. Whole blood includes all cellular components (red blood cells (RBCs), white blood cells (WBCs), platelets) and fluid components. The cells are separated from the liquid supernatant by centrifuging whole blood. If anticoagulants are added to whole blood before centrifugation, the blood does not clot, and plasma is obtained. Plasma contains all coagulation and fibrinolytic factors in their active form. Serum is obtained through centrifugation after coagulation (no addition of anticoagulants, i.e. no clotting inhibitor is added), so that the coagulation and fibrinolytic factors are not present.
 

Components of blood testing

Blood collection systems

Coagulation inhibitors need to be added in order to obtain plasma. The following additives are available: citrate, EDTA, heparin, lithium heparin, sodium citrate and sodium fluoride. The choice of additive depends on the analysis that is to be carried out.

There are two different basic systems available for blood collection that transfer the blood into the cannula either through aspiration or through negative pressure. Both systems use tubes with colour coding on the cap for identification of the respective additive.

Blood collection systems

Becton Dickinson
Requested sample material or testCap colourProduct name
Serumred BD Vacutainer® Serum Tube
Serum-GelgoldBD Vacutainer® SST™ II Advance Tube
Citrated bloodlight blueBD Vacutainer® Citrate Tube
EDTA bloodpurpleBD Vacutainer® EDTA Tube
Lithium heparin bloodgreenBD Vacutainer® Heparin Tube
Glucose determinationgreyBD Vacutainer® Tube for Glucose and Lactate Determination
Homocysteine determinationgreyBD Vacutainer® for Homocysteine Determination
Metal determinationdark blueBD Vacutainer® Tube for Trace Element Determination
Sarstedt
Requested sample material or testCap colourProduct name
Serumwhite    S-Monovette® Serum
Serum-Gelbrown    S-Monovette® Serum-Gel
Citrated bloodgreen    S-Monovette® Coagulation
Lithium-heparin bloodorange    S-Monovette® Plasma
Glucose determinationyellow    S-Monovette® Glucose
Glucose determinationgrey    S-Monovette® GlucoEXACT
Plateletsred    S-Monovette® ThromboExact
Plateletsturquoise    S-Monovette® for PFA 100
Homocysteine determinationgrey    S-Monovette® Homocystein Z-Gel
Metal determinationorange    S-Monovette® for Metal Analysis                                      

Blood collection

Blood sample collection can be classified as arterial, capillary or venous. Arterial blood collection is used for blood gas analysis, and is the most invasive technique. Capillary blood collection is used to collect micro-volumes of blood. However, blood collection from a vein is the most common blood collection method in practice.