Chemicals
for blood gelatin assay amongst others polyisobutylmethacrylate
(PIBM), disodium hydrogen phosphate dodecahydrate and sodium
dihydrogen phosphate dihydrate were purchased from Sigma-Aldrich
Chemie GmbH (Steinheim, Germany) and Bernd Kraft GmbH
(Duisburg, Germany), correspondingly. Chromabond C18 polypropylene
columns (500 mg/6 mL) for solid phase extraction were purchased
from Macherey-Nagel GmbH & Co. KG (Düren, Germany)