A Simplified Technique for the Preparation of Glass Paper Impregnated with Silicic Acid J. W. Dieckert, W. B. Carney, R. 1. Ory, and N. J. Morris, Southern Utilization Research and Development Division, U. S. Department of Agriculture, New Orleans 19, La. EYERAL articles (1-5) on paper cliros m :It o,rnpliy r dcscri1)c t h r us(' of glass fibcr filtcr paper inilircgnat~ctl ivitli silicic acid. Sulfuric acitl \rn. reportctl t o 1)c :t uscful rcngrnt for locating tlir (,lirom:ttograplicd suhst:uicw. However, the lark of specificity of sulfuric3 acid in its cliarring :trtion on organic compounds makes it' impcrative that all interfering organic impurities be removed from the paper liefore chromatography is begun. A proccdure for removing these impurit'ies was described by Dieckert and Rciser ( 4 ) ; as glar;~ paper is w r y weak n-hcn n-et,. consideralile care was ncrdcti in impregnating the p a l m with silicic wit1 to prevent tearing. This publication dcscrilm a more efficient method for removing tlir organic impurities from the glass paper and a method for impregnating the paper with silicic acid that overcomes the difficulties caused hy weak paper.
EXPERIMENTAL
Removal of Organic Impurities. Sheets of glass fiber paper (KO. X934-AH, H. Reeve dngel and Go., 52 Duane St., S e w York, K. T.) of suitable size, each having a holr punched through one end, were strung on a glass rod a fen- millimeters apart. T h e rod was hung in a battery jar covered with a loose fitting lid, both of borosilicate glaqs. T h e container was then placed in an annealing oven and heated a t 600" C. for 1 hour. Impregnation of Paper. A stock solution of potassium silicate was prepared as desciibed by Dieckert and Reiser (4). The sheets of glass paper. freed of organic impurities, were suspended by common office binder clamps, (3/*-inch capacity). They were dipped in a dilute solution of potassium silicate (1 part of stock solution with 9 parts of water), and hung in a drying oven. When the silicate treated strips were thoroughly dry, they were stiff and had considerably more strength than before the treatment. The strips were then soaked in 4 S hydrochloric acid for 5 minutes. Carbon dioxide n-as evolved. but did not cause serious damage to paper which had been dried adequately. After the acid treatment, the sheets were soaked in successive batches of distilled water until the wash water was
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ANALYTICAL CHEMISTRY
neutral to pH paper. When the papers had hccn soaked in four batches of water for a minimum of 5 minutes cacli, thc w:i
