Serum: Allow samples to clot for 2 hours at room temperature or overnight at 4 ℃ before centrifuged for 15 minutes at 1000×g. Collect the supernatant and carry out the assay immediately. Blood collection tubes should be disposable, non-pyrogenic, and non-endotoxin.
Plasma: Collect plasma with EDTA or heparin as anticoagulant. Centrifuge the samples for 15 minutes at 1000×g at 2-8℃ within 30 minutes of collection. Collect the supernatant and carry out the assay immediately. Hemolysis samples are not suitable for ELISA assay.
Cell culture supernatant: Centrifuge the supernatant for 20 minutes to remove insoluble impurity and cell debris at 1000×g at 2-8°C. Collect the clear supernatant and carry out the assay immediately.
Tissue homogenates: It is recommended to get detailed references from other literatures before assay against different tissue types. For general information, hemolysis blood may affect the result, so you should mince the tissues into small pieces and rinse them in ice-cold PBS (0.01M, pH=7.4) to remove excess blood thoroughly. Tissue pieces should be weighed and then homogenized in PBS (The volume depends on the weight of the tissue) with a glass homogenizer on ice. To break the cells better, you can sonicate the suspension with an ultrasonic cell disrupter or subject it to freeze-thaw cycles. Then centrifuge the homogenates for 5 minutes at 5000×g to get the supernatant.
Cell homogenates: Take the cell cultured plate or cell suspension, then wash the cell cultured plate with PBS (pH=7.2~7.4). Lyse the cell by frequent freeze-thaw cycles or adding lysate. Centrifuge the samples for 15 minutes at 1000×g at 2-8℃, collect the supernatant and take frozen stock sub-packaged.
Urine/ Cerebrospinal fluid/ Broncho alveolar lavage fluid/ Synovial fluid: Collect samples and centrifuge samples for 15 minutes at 1000×g at 2-8℃, Collect the supernatant and take frozen stock sub-packaged.
Feces: Collect feces and suspend the stool with 0.01M PBS (pH=7.2~7.4). Oscillate on the ice for 15min, then centrifuge at 4℃ for 5min. Collect the supernatant and take frozen stock sub-packaged.