The acylation reagent TFAA as anhydride creates corresponding acids as by-products. Excess reagent and the acid formed have to be removed. Acylation with fluorinated acid anhydrides forms stable derivatives suited for FID as well as for ECD detection. These products contain harmful substances which must be specially labeled as hazardous. For detailed information please see SDS. These products contain harmful substances which must be specially labeled as hazardous. For detailed information please see SDS.