Samuel Shapiro U. S. Army Engineer Research
and Development Laboratories Fort Belvoir, Virginia
I
1
Device to Convert a Hypodermic Syringe into a Multi-Purpose Apparatus
The hypodermic syringe can be used for many purposes other than that of transferring fluids into or out of living organisms. The simple base or holder described in this paper will keep a Luer or other type of hypodermic syringe and its contents in an upright position so that it can be used for the following purposes: (1) The rapid, accurate weighing and transferring of volatile, viscous, or other types of liquids. (2) The heating and/or cooling of small amounts of liquids. The entire assembly (Fig. 1A) consisting of the base and the syringe can he placed in a heat,ing or cooling bath until the contents of the syringe reach the desired temperature. (3) As a substitute pycnometer or specific gravity bottle for the determination of specific gravities. (4) A series of holders affixed to a rectangular base (Fig. 1B) makes a handy storage rack for partially filled syringes. (5) As a calibrated pipet or dropping device. Through the use of calibrations on the syringe barrel, amounts as small as 0.01 ml can be accurately delivered. Essentially the device consists of a flat, circular brass disc approximately two inches in diameter. Affixed to its center is a holder made from that part of the hypodermic needle which fits over the tip of the syringe. The size and shape of the base can be modified to suit any special need. Placing the tip of the syringe into the holder seals it against loss by evaporation and keeps it in an upright
In use, the volatile liquid is drawn up into the barrel of the syringe in the usual manner. The needle is removed, the tip of the syringe is then placed in the holder of the utility base, and the ent,ire assembly is placed on the pan of an analytical balance and weighed. The syringe is then removed from the holder, an estimated amount of the liquid needed is ejected into t,he proper receiver, and the syringe is re-inserted into the same holder and reweighed. The difference between the two u-eighings is the amount delivered in the receiver. The use of a large gauge hypodermic needle for filling the syringe keeps the tip clean. A ncedle should not be used when the liquid is transferred from the syringe into the receiver prior to the second weighing because liquid will be left in the shaft when the needle is removed. The device can be easily constructed from a circular piece of brass 2 in. in diameter and in. thick. The shaft of the needle is broken off close to the section that is inserted over t,he tip of the syringe. The remaining portion of the base is filed smooth and soldered to the metal plate. The soldering should completely encircle the holder so that no air can he admitted. r'1' g ure 1B shows a modification of this device being used as a rack for the storage of a number of eyringes of varying sizes. The necessity for the repeated use of the balance can be eliminated when the same amount of the liquid has to be weighed out a number of times. The amount desired is weighed only once and the volume it displaced in the .syringe is used for the measuring of subsequent amounts. When used for specific gravity determinations the syringe is used in the same manner as a pycnometer. The availability of inexpensive plastic hypodermic syringes brings down the cost of this techniqw to a matter of pennies, provided the liquids used do not react with the plastic from which the syringe is made. If there is a reaction then the glass type must he used. Glass must also be used in a water bath for the heating of liquids. When used with substances that arc difficult to clean the plastic syringe is thrown away. These syringes were originally made for physicians for one time use. Acknowledgment
Figure 1 . (A1 The bare and syringe arrembly r e a d y for weighing; (8) the bore u.ed as o rtoroge rock for prti.lly tilled syringes.
Appreciation is expressed to Woodrow Thurston, laboratory mechanic, for fabricating the various holders.
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/ Journal of Chemical Education
