Abstract: Blood sample collection tubes are described including a tube surface and a coating set comprising a tie coating or layer N of SiOxCy or SiNyCy applied to the tube surface, a barrier coating or layer of SiOx, and a pH protective layer of SiOxCy or SiNyCy. The C tubes optionally contain a fluid with a pH of 4 to 8, alternatively 5 to 9. The barrier coating or layer prevents oxygen from penetrating into the thermoplastic tube, and the tie coating or layer and pH protective coating or layer together protect the barrier layer from the contents of the tube. Processes of collecting high volumes of blood into the tube, and methods of isolating the various types of nucleic N acids from the collected blood sample are described.