LIBRARY 
 STAjffieP^T BOARD 
 
 ET-268 
 
 United States Department of Agriculture 
 
 Agricultural Research Administration 
 
 Bureau of Entomology and Plant Quarantine 
 
 A MECHANICAL EXTRACTION APPARATUS 
 
 By H. D. Mann 
 Division of Insecticide Investigations 
 
 A dual-purpose extraction rack (Mann 1), designed and constructed 
 in this laboratory, facilitated the handling of a large number of separa- 
 tory funnels during the colorimetric determination of DDT in milk and 
 fats by the method of Schechter et^aL (2). However, even with this rack 
 the determination procedure was still tiresome and time-consuming, 
 and required an unduly large amount of acid because the extraction was 
 not carried to completion. A mechanical extraction apparatus that cuts 
 in half both the extraction time and the acid requirements has now been 
 devised. The design of this rack is based on the same principle as the 
 one previously described. 
 
 This apparatus has two banks of eight 500-ml. separatory funnels 
 one above the other (fig. 1, A). Each bank is hinged (fig. 2, B) to a 
 carriage (C) so that during the extractions it can be folded backward 
 until the funnels are at about a 60- degree angle, with the stoppers 
 resting on a strip of foam rubber mounted on a board (D). Each bank 
 consists of three notched boards, one (figs. 3 and 4, J) to fit above the 
 stopcocks to hold the funnels in the normal position and two others 
 (H and F) to fit around the necks of the funnels to keep them in the banks 
 when they are upside down. Board F is attached to board H with hinges 
 (fig. 3, G) made by welding together pieces of two screen-door holders. 
 With these spring-type hinges, F can be kept down around the necks of 
 the funnels during the extraction but can be easily raised to remove 
 them when the extraction is completed. Each bank of funnels is shaken 
 back and forth on a horizontal track (fig. 1 and 2, E) by a 2 -inch driving 
 arm attached to the shaft of a 1:10 reducing gear (K) connected to the 
 carriage by a 9 -inch connection rod (L). A 1/8 -hp. motor (J) with a 
 capacity of 1140 r.p.m. furnishes the shaking power for each bank. 
 
 After the extraction both banks of funnels are turned down to their 
 normal position on the shelves (fig. 5, N) which are mounted on an 
 upright bar attached to the framework so that the tips of the funnels in 
 the upper bank will be directly over and close to the necks of the funnels 
 below (fig. 3). 
 
 During the last half of the last sodium sulfate -sulfuric acid extraction 
 the upper bank is elevated with pins (fig. 5, Mj, so that the lower bank 
 can be folded back in the shaking position. After the extractions have 
 
 JUL 1- 
 
been completed, the chloroform solutions are combined in the upper 
 funnels. The lower funnels are cleaned with warm water, the upper 
 bank is kept in the elevated position, and the chloroform solutions are 
 filtered through plugs of cotton held in glass Gooch crucible holders, 
 which rest in the necks of the lower funnels as shown in figure 1. Here 
 the chloroform solutions are washed with a sodium bicarbonate solution 
 and again filtered through plugs of cotton into 5 00 -ml. Erlenmeyer flasks 
 with standard 24/40 joints. 
 
 A time switch has proved valuable in the extractions, but safety 
 switches (fig. 5, O) are then necessary to cut off the motor in case the 
 time switch is turned on accidentally when the bank is in the normal 
 position. 
 
 Literature Cited 
 
 (1) Mann, H. D. 
 
 1947. A dual-purpose extraction rack. U. S. Bur. Ent. and Plant 
 Quar. ET-243, 2 pp., illus. ^rocessedj 7 
 
 (2) Schechter, M. S., Pogorelskin, M. A., and Haller, H. L. 
 
 1947. Colorimetric determination of DDT in milk and fatty 
 
 materials. Indus, and Engin. Chem., Analyt. Ed. 19: 51. 
 
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UNIVERSITY OF FLORIDA 
 
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