Since FID analyzers generally have an incomplete response to alcohols and carbonyls, determine each FID analyzer's alcohol/carbonyl response factor (RFOHCi[THC-FID]) after FID optimization to subtract those responses from the FID reading. Use the most recently determined alcohol/carbonyl response factors to compensate for alcohol/carbonyl response. You are not required to determine the response factor for a compound unless you will subtract its response to compensate for a response.
CFR 40-1065.845-2014 history
2014CFR 40-1065.845-2014 Protection of Environment. Part1065:Engine-testing procedures. Section1065.845:Response factor determination.