UNITED STATES DEPARTMENT OF THE INTERIOR GEOLOGICAL SURVEY Determination of Total Sulfur in Lichens By Combustion-Infrared Analysis

Abstract Sulfur was determined in Parmelia sulcata and P. chlorochroa by combustion of the sample and infrared detection of evolved sulfur dioxide using an automated sulfur analyzer. Vanadium pentoxide was used as a combustion accelerator. Pelletization of the sample prior to combustion was not found advantageous. Washing studies showed that leaching of sulfur was not a major factor in the sample preparation. The combustion-IR analysis usually gave higher sulfur content than the turbidimetric analysis as well as shorter analysis time. Relative standard deviations of less than 7% were obtained by the combustion-IR technique when sulfur levels in lichens ranged from 0.05-0.20%. Determination of sulfur in National Bureau of Standards orchard leaves standard reference material showed good agreement between the combustion-IR technique and other instrumental procedures