The fresh pig blood samples used for this study were obtained from a slaughter house in Erlangen ( Bavaria , Germany ). The pigs were cut at the throat and the blood was collected directly into glass bottles which already contained a 0.1 M sodium citrate solution (Alfa Aesar, Karlsruhe , Germany ) to prevent coagulation. The volume of the sodium citrate solution and the blood was in the ratio of 1:10 (50 ml of sodium citrate for 500 ml of blood). The samples were then immediately subjected to a SAFE (see below) without any further delay. A total of four blood samples from four different pigs were obtained for the identification of the odor active compounds in the pig blood

Dichloromethane (DCM) was purchased from Acros organics ( Nidderau , Germany ). Water used to prepare the sodium citrate solution was purified in a Micropure system from TKA ( Niederelbert , Germany ). An alkane solution    (C₆-C₃₄) in DCM was used to calculate the retention index values of the analytes in the blood samples. The following reference compounds were used for the identification of the blood volatiles: 2,3 butadione (Fluka, Neu-Ulm, Germany), 2-methyl nonanoic acid (Alfa Aesar, Karlsruhe, Germany), vanillin,   δ -octalactone (ABCR, Karlsruhe, Germany), trans-4,5-epoxy-(E)-dec-2-enal, (Z)-octa-1,5-dien-3-one (Aromalab, Freising, Germany), acetic acid, Z-4-heptenal, octanal, 3-(methylthio)-propanal (methional), 4-methyl phenol, 1-octen-3-one, hexanal,  phenyl aceticacid, δ -nonalactone, 4-methyl nonanoic acid, androstenone ( 5 α -androst-16-en-3-one) (Aldrich, Steinheim, Germany), androstadienone ( androsta-4,16,-dien-3-one ) (Steroids Ltd, Illinois, USA)