Figure 7. Stability of TAP in serum plasma and urine. Synthetic APFD4K was incubated in fresh serum, urine, EDTA plasma, boiled serum or Tris-HCl buffer, pH 7.4, containing CaCl2 for up to 48 hours. Samples were withdrawn at regular intervals, boiled and later analyzed for irTAP using the 9801 antibody-based radioimmunoassay.