benzene in the carbon dioxide product an expensive photoionization detector pid is needed while after sample concentration a much cheaper flame ionization detector fid can be used also for detecting sulfur impurities in the 20 to 50 ppb range an expensive sulfur chemiluminiscence detector scd is needed while after sample concentration a cheaper flame photometric detector fpd can be used the sulfur analyzer unit will analyze either the total sulfur or individual sulfur species during various process stages for beverage grade carbon dioxide the total sulfur in the product excluding sulfur dioxide needs to be below 0 1 ppm and sulfur dioxide needs to be below 1 ppm for the measurement of total sulfur sulfur impurities are oxidized to sulfur dioxide in a catalytic reactor with a sulfur tolerant catalyst or inside an ozone generator typically based on corona discharge sulfur dioxide after the oxidation is analyzed using a sulfur specific detector such as sulfur chemiluminiscence detector scd flame photometric detector fpd or pulsed flame photometric detector pfpd when speciation of sulfur compounds is required the sulfur impurities may be optionally concentrated and sent directly to a separation column and the detector bypassing the oxidation unit the hydrocarbon analyzer will analyze both the total hydrocarbons as methane or.