Blood analyzers are mechanized computer operated machines that count the different types of compounds found in blood samples, as well as perform coagulation tests. Identifying the compounds and their quantity can be determined by adding specific reagents and then analyzing with optic or electric sensors. The reagent that is added to the sample depends on the kind of test that is being performed. The sample and reagent mixture is analyzed with a computerized photometer or an ion selective electrode to identify compounds. These techniques provide measurements that are used to categorize, compute, and define cell populations. Some common tests identify blood cells, platelets, and hemoglobin levels found in a sample. In a standard sample there are 600 red blood cells, one white blood cell and 40 platelets. The electrical technique involves diluting the blood and passing it through a small hole in which electricity runs through. When the cells pass through this opening the electric current changes. A reagent is then added to the blood solution to select only red blood cells. This leaves white cells and platelets. The solution is passed through the electric current again. From here, the components are then counted due to ratio of white blood cells to platelets.
Optical detection focuses on the population of white blood cells. A diluted solution of the blood sample and reagent is used. This solution is passed through a flow cell. A flow cell allows cells to pass one at a time through a tube past a laser beam. The reflective quality and light transmission of the cells is analyzed by software. The software then gives a number of the likely distribution of different cells.
Coagulation tests or coagulmeter, measures the ability of a blood sample to clot. A blood sample is tested with sodium citrate. Sodium citrate is a type of anticoagulant. It is a type of sodium salt that can be found in citric acid. Sodium citrate is used because the anticoagulant effect can be reversed. The evolution of clotting is monitored optically by measuring the absorbance of particular light wavelengths in the sample. The clotting capability is also monitored by how it changes over time.