Wheaton chemical oxygen demand vials for sale factory-glass clear safety coated 40ml VOA vials with high quality Wheaton VOA Vials - Open Top Closures and Septum Generally used for volatile organic compound analysis and sample storage, our 20mL, 40mL, and 60mL VOA vials are available in clear or amber borosilicate glass with a choice of .25" or .00" PTFE/Silicone septa.