APPENDⅨ/ PROTOCOL E Pesticide Analytical Manual Vol I verify retention times and response characteristics previously found. Note this on Reporting Form prepared for methyl ether/ester reference stan- dard test results Determine efficiency of methylation by direct comparison to methyl es- er/ether reference standard, if available. Report percentage conversion to methylated product on Reporting Form B If methyl ester/ether refer ence standard is not available, assume complete methylation of chemical for calculating amount of reference standard causing 50% FSD Stop work if acid/ phenol cannot be methylated or if there is no GlC response to ester/ether. Recovery Through GPC and Florisil Methyl Ester/Ether Reference Standard In duplicate, place 1-100 ug methyl ester/ether reference standard, in 1 10 mL hexane, on Florisil column prepared as described in Section 402 CIc.(Use Florisil that has been shown to permit elution of both hep- tachlor epoxide and endrin by eluant 2 [Section 204].) Elute columns with 35 mL eluant 1, 60 mL eluant 2, and 100 mL ethyl ether, and determine percentage recovered in each eluate If total recovery is <g0%, report results on Reporting Form B and termi- nate work Acid/Phenol Reference Standards Place 100 ug acid/ phenol reference standard, dissolved in 50% methylene chloride/hexane, on calibrated GPC column and elute as directed in ection 402 cla Methylate collected fraction according to Clb Determine percentage recovery by comparison to methyl ester/ether ref erence standard, if available, or to reference standard previously methy lated in laboratory If recoveries are <30%, report results on Reporting Form B and terminate work Recovery Through Complete Method Select one representative fatty and one nonfatty food. Analyze by Section 402 using extraction module appropriate to commodity, to ensure that there are no interferences with chemical being tested. Simultaneously, nalyze reagent blank for further information on source of possible inter- ences Fortify duplicate portions of food samples with 1-2 mL acetone solution of acid/phenol reference standard at tolerance level or, if no tolerance ex- ists, at 0.05 ppm APPENDIX‖10 FormTransmittal No. 94-1 (1/94) APPENDIX II-10 Form FDA 2905a (6/92) APPENDIX II/PROTOCOL B Pesticide Analytical Manual Vol. I verify retention times and response characteristics previously found. Note this on Reporting Form prepared for methyl ether/ester reference stan￾dard test results.) • Determine efficiency of methylation by direct comparison to methyl es￾ter/ether reference standard, if available. Report percentage conversion to methylated product on Reporting Form B. If methyl ester/ether refer￾ence standard is not available, assume complete methylation of chemical for calculating amount of reference standard causing 50% FSD. Stop work if acid/phenol cannot be methylated or if there is no GLC response to ester/ether. Recovery Through GPC and Florisil Methyl Ester/Ether Reference Standards • In duplicate, place 1-100 µg methyl ester/ether reference standard, in 1- 10 mL hexane, on Florisil column prepared as described in Section 402 C1c. (Use Florisil that has been shown to permit elution of both hep￾tachlor epoxide and endrin by eluant 2 [Section 204].) • Elute columns with 35 mL eluant 1, 60 mL eluant 2, and 100 mL ethyl ether, and determine percentage recovered in each eluate. • If total recovery is <30%, report results on Reporting Form B and termi￾nate work. Acid/Phenol Reference Standards • Place 100 µg acid/phenol reference standard, dissolved in 50% methylene chloride/hexane, on calibrated GPC column and elute as directed in Section 402 C1a. • Methylate collected fraction according to C1b. • Determine percentage recovery by comparison to methyl ester/ether ref￾erence standard, if available, or to reference standard previously methy￾lated in laboratory. • If recoveries are <30%, report results on Reporting Form B and terminate work. Recovery Through Complete Method • Select one representative fatty and one nonfatty food. Analyze by Section 402, using extraction module appropriate to commodity, to ensure that there are no interferences with chemical being tested. Simultaneously, analyze reagent blank for further information on source of possible inter￾ferences. • Fortify duplicate portions of food samples with 1-2 mL acetone solution of acid/phenol reference standard at tolerance level or, if no tolerance ex￾ists, at 0.05 ppm