Procedures for removing background contaminants from reagents were tested. The reagents used were deionized water (7732185), 10 percent phosphoric-acid (7664382), 30 percent glycerin (56815), 2,2,4-trimethylpentane (540841), alumina (1344281), pesticide grade acetone (67641), sodium-chloride (7647145), and anhydrous sodium-sulfate (7757826). Nitrogen (7727379) gas was used to purge volatile contaminants from deionized water, 10 percent phosphoric-acid in water, and glycerin in water. Alumina chromatography was used to remove interferences from 2,2,4-trimethylpentane. Liquid/liquid partitioning followed by azeotropic redistillation was used to purify acetone. The fumigant method used had grain products leached with acetone/water solution that also contained phosphoric-acid, sodium-chloride, and glycerin. An aliquot of the leachate was partitioned with trimethylpentane and dried over anhydrous sodium-sulfate. Chloroform (67663) was the most difficult contaminant to remove from all reagents, especially acetone. Chloroform was more easily removed from the other reagents, but it was considered best to use reagent blanks that contained no chloroform when purchased. Laboratory water contained fewer background interferences than did tap water. In either case, the inert gas purging of volatile contaminants was effective. The removal of interference from trimethylpentane worked best when alumina was fresh. Gas purging did not effectively remove volatile contaminants from acetone/water solutions. In a reagent blank resulting from these clean up procedures, interference from dichloromethane (75092), carbon-tetrachloride (56235), and tetrachloroethylene (127184) were successfully removed from all reagents. However, a chloroform peak, from contaminated phosphoric-acid, persisted. The author concludes that the gas chromatography background interferences caused by reagent contamination has brought a trend toward minimal reagent use; however, the simultaneous determination of ten or more fumigants in grain still requires reagent media that effectively extracts these residues while providing analyte stability.