Peripheral blood is a critical sample type for research and clinical applications, but conventional EDTA tubes have a narrow processing window (within ~2 hours). This Technical Note evaluates two blood collection tubes (BCTs) that extend this window: Streck Cell-Free DNA (Streck), which supports peripheral blood mononuclear cell (PBMC) workflows, and PAXgene Blood RNA (PAXgene), which supports leukocyte workflows and adds flexibility with fresh or frozen blood. Processing steps for PAXgene BCTs are also detailed in this document.