Thanks for getting back to me. The mixture is 4800 ppm N-Hexane in Air. We have a database in which I need to put this information. The way the database is set up, I need to enter the total weight of the gas in the cylinder, and then multiply that by the percentages (4800 ppm = 0.48%)to get the breakout by gas. It appears to me that your answer is breaking the gases down to get the conversion of each gas first. Is this because each gas has it's own g/mole? Is there a way to convert the mixture based on cubic feet? Thanks again!