Stabilized blood separating composition

Claim 1

In a thixotropic composition useful as a chemical and physical barrier between serum and clot portions of separated blood, the composition comprising a gel-like material having a specific gravity within the range of about 1.030 to 1.090 and consisting of a dimethylsiloxane silicone fluid having an inert siliceous filler dispersed therein, the improvement which comprises the addition of a network former in a quantity sufficient to maintain the viscosity of the composition within the range of 200,000 to 600,000 centistokes for prolonged periods of time, the network former consisting of a polysiloxane-polyoxyalkyl copolymer represented by the following formual ##STR2## where the monomeric units are randomly distributed and Me represents --CH 3 ; x represents a number between 80 and 120; y represents a number between 8 and 12; P represents a polyoxyalkyl side chain represented by the formula CH.sub.2 --CH.sub.2 --O).sub.m (CH.sub.2 --CH.sub.2 --CH.sub.2 --O).sub.n where the monomeric units are randomly distributed and m represents a number between 20 and 30; and n represents a number between 1 and 30.