SEPTEMBER. 1951
a
THE SEPARATION OF ANIONS BY PAPER PARTITION CHROMATOGRAPHY WILL S. DeLOACHa and CHARLES DRINKARDS Huntingdon College, Montgomery, Alabama
A PROCEDURE has been described by Frierson4 for the separation of cations by paper partition chromatography. This procedure has been adapted to the separation of a group of anions consisting of phosphate, arsenate, sulfide, ferricyanide, ferrocyanide, and iodide ions. These ions were chosen because they are common ones that give colored precipitates with silver ion. The separation was carried out in a can about 50 cm. tall and 15 cm. in diameter. The can was covered with a piece of cardboard during use. A graduated cylinder of suitable height was placed inside the can to serve as a support for a Petri dish which held the developer. A mixture of 40 per cent of n-hutanol, 40 per cent of ethanol (95 per cent), and 20 per cent of water by volume was used as the developer. A strip of filter paper 25 cm. long and about 2 cm. wide was notched on each side about 1 to 2 cm. from one end. This notching narrowed the width of the paper at that point and so restricted the flow of the developer. The solution of the ions, which was 0.5 M with respect to each anion, was put on the paper strip about 1 to 2 cm. from the notch on the long side by means of a dropper that had been drawn out to a h e point. The strip of paper was placed on a blotter and the dropper containing the solution was drawn quickly across the strip to form a line straight across and about 0.1 cm. in width. Too wide a line caused the bands to he too wide and not well defined. The line should he uniform in width. There was a tendency for a wide
spot to form at the edge where the dropper first touched the strip. This was overcome by pressing the strip firmly against the hlotter. The strip of paper was then folded between the notch and the line of solution and the short end hung over the edge of the Petrie dish and dipped into the developer. The long end of the strip then hung, without touching anyth'mg, in the can. As many strips could be developed a t once as the dish would hold without crowding. After the strips were placed, the can was covered and allowed to stand for 20 to 24 hours a t a temperature of 20' to 25'C. During this time the anions were moved down the strip and separated. The strip was then removed, dried with a hot air blast, and sprayed with 0.1 M silver nitrate solution from an atomizer. Bands,of colored precipitates formed to show the locations of the anions. A blank was run to detect any bands due to impurities. None was found. The order of separation, from top to bottom, was: ferrocyanide, ferricyanide, sulfide, arsenate, phosphate, and iodide. The ferrocyanide appeared on spraying with silver nitrate solution as a 2-mm. light green band with a light yellow band below and adjoining it. The ferricyanide appeared as a 2-mm. orange hand just helow the ferrocyanide. The sulfide appeared as a 5-mm. gray-brown band. The arsenate appeared as a 1-cm. red-brown hand. The phosphate appeared as a very light 1-cm. hand that darkened fast on exposure to light of the room. The iodide appeared as a 1-cm. yellow band that darkened slowly on exposure to light of the 1 This paper is based on work done by Charleles Dnnkard in a room. The approximate Rf values of these ions a t senior course in Independent Study. "resent address: Mississippi State College for Women, 30°C. are: ferrocyanide, 0.12; ferricyanide, 0.15; sulColumbus, Mississippi. fide, 0.16; arsenate, 0.26; phosphate, 0.37; and iodide, "resent address: DeDartment of Chemistrv. " . Alabama Polv- 0.92. Temperature change caused considerable variatechnic Institute, ~ u b n Alabama. 6 tion in the rate of movement of the ions but did not 4 FRIERSON, W. JOE, AND MARYJO AMMONS, TAIS JOURNAL, change the order. 27,3723 (1950).
