Document nm0q72No6dzkm6vNe7VRYxRx6

'A Monsanto Monsanto Company 1700 South Sacond Street St. Louis. Missouri 63177 Phons: (314) 621-4000 October 14, 1969 ORGANIC CHEMICALS DIVISION Mr. Francis Coon Wisconsin Aluraini Research Foundation Institute Madison, Wisconsin 53706 Dear Mr. Coon: . I have shipped to you, under separate cover, 2 pounds each of Aroclor 1242, 1254 and 1260. I have also checked with our mass spectroscopists with regard to the minimum amount of PCB required for an unequivocal identification^ The figure given me is 1 microgram. This amount may seem high but as you know we are working with a large number of isomers. In answer to Don Hughes questions on partition solvents, I have'included some tables showing the results of our partition experiments with various solvents. In terms of recovery, I think this demonstrates that DMF is the better solvent. . The TLC work we have done was all with Silica Gel G plates, activated at 110C for 4 hours. The best solvent systems were hexane-acetone (98/2) and hexane-acetic acid (98/2). While reasonable separations were obtained we discarded this procedure because.of the time required. Please advise me when you are ready to ship the samples and extracts we discussed. When they are sent to us, it would be helpful if the chromatograms and your estimated amounts are included. . Sincerely, 9S'.7#7/^ db cc: R. E. Keller M. W. Farrar W. R. Richard IE. P. Wheeler E. S. Tucker Senior Research Chemist DSW 162313 STLCOPCB4040923