The BD Vacutainer® SST II Advance tubes utilize an inert gel to effectively separate serum from blood clots during centrifugation, preventing serum contamination by cellular components. Time-sensitive analytes like potassium, phosphorus, and glucose remain stable even after a week of storage at 2-8ºC when processed with BD SST II Advance tubes. Clinical evaluation of various chemistries, including therapeutic drugs, proteins, peptides, steroids, and vitamins, attests to the exceptional stability provided by the acrylic gel in these tubes.