A cut off for the minimum number of matches allowed could also be added. A noise level may be added to the unknown peaks by placing “ones” in locations adjoining the measured unknown peaks. Note that this increases neither the storage requirement nor the compute time. A more sophisticated approach is to give a noise distribution to the unknown peaks such as “ones” for the reported values, “one-half,” on each side of reported values, and “zeros” for all others. In conclusion, the described algorithm may be simply coded in a compiler language, is conservative in memory use, and is still quite rapid in determining which standard spectra can possibly be contained within an unknown
mixture. The same algorithm has also been implemented as a first filter for unknown mass spectra.
ACKNOWLEDGMENT The author wishes to acknowledge the Department of Chemistry, Colorado State University, Ft. Collins, Colo., 80521, where he was visiting professor when this work was done. Further, Tom Copeland and Ken Olson are acknowledged for their help and comments. Received for review February 20, 1973. Accepted April 13, 1973. The financial support of the National Science Foundation is gratefully acknowledged.
Improved Separatory Funnel Narbik A. Karamian Division of Research Services, Environmental Services Branch, National institutes of Health, Bethesda, Md. 20014
There are various methods for the extraction and separation of two liquids present in two distinct layers. The simplest method is to decant one layer from the other. However, this is not a very accurate and effective method because it is not possible to obtain an exact separation of one layer from another and the procedure is also time consuming. Conventional laboratory type separatory funnels are an improvement over decantation methods with regard to the exactness of separation; but the use of such devices is limited to the removal of the lower layer first. Partial contamination of the upper layer during draining also occurs. however, since it intermixes in the stem or on the funnel wall with residual amounts of the lower layer. The use of separatory funnels in chemical and biological processes is obviously widespread. It is frequently important, for example, to analyze solutions that contain elements in the form of impurities, such as trace metals, that are present in concentrations of parts per billion or lower. This analysis can be conveniently carried out by concentrating the impurities by a solvent extraction step, then measuring and identifying them by means of chemical reactions and instrumental analyses. For example, a trace metal solvent extraction is generally carried out by adding a chelating agent that effectively complexes the impurities. A buffer solution is also added and the chelated substances are then extracted from the large solution volume into a small solvent volume. If the solution and the volume of solvent are very carefully controlled, the impurities can be quantitatively concentrated from parts per billion or lower, by a factor of lo3 or more. The analysis is completed by removing the solvent layer containing the extracted chelated impurities from the solution and then measuring and identifying the impurities within it. The devices of this invention are distinct improvements on the design of the separatory funnel and allow rapid, nontedious, multiple extraction and separation of the sample and selective withdrawal of either of two immiscible liquid layers. Figure 1 illustrates a separatory flask container (10) with a stopper closure (11) a t the upper end. At the lower portion (12), the container section connects with a fitted plug (13), which maintains and seals against any leakage around the washer (14). A lock nut device (17) holds the lower portion (12) in contact with the washer (14). The conduit (16) is adjustable by a sliding motion in the plug 2154
(13) and is sealed into it by means of an O-ring (21). In the lower part of the conduit (16) within the plug (13), there is a drainage hole (25) which is brought into alignment with the plug drain hole (26) when it is desired to remove a lower liquid layer. When not in alignment, the upper liquid layer can be removed. This alignment is accomplished by removing the disk lock washer ( 2 8 ) , moving the conduit (16) upward until the flair nuts (27) and (29) meet. The operation of these separatory funnels is practically self-explanatory; however, an extraction using the separatory funnel of Figure 1 will be described. Following an extraction, the substance being sought is transferred from the aqueous sample layer into the solvent layer, for example, methyl isobutyl ketone. Methyl isobutyl ketone is the upper layer since it is lighter than aqueous solution. During this procedure, the drain holes (25) and (26) are in a non-alignment. The height of the conduit (16) is adjusted to the lower level of the methyl isobutyl ketone layer. The solvent layer is then removed by means of the stopcock (18). At this stage, if desired. a second extraction can be performed by simply adding another portion of methyl isobutyl ketone equal in volume t o the first portion and the procedure repeated. This upper layer is also removed via stopcock (18) and combined with the first extracted portion. The aqueous lower layer is removed from the flask by aligning drain holes (23) and (26) and draining ria the stopcock (18). This alignment as mentioned above, is accomplished by manipulation of flair nuts ( 2 7 ) and (29) and lock washer (28). Figure 2 shows the separatory funnel utilizing a threechambered flask structure. In a typical flask of this type, the largest compartment (10) is carefully calibrated to contain a fixed volume of aqueous sample. The second compartment (11) is also calibrated and used for holding an exact volume of organic solvent. The volume relationship between the two compartments (10) and (11) is in the range of 10 to 1 to 100 to 1. The volume of the third compartment (12) is unimportant since its function is to facilitate mixing of the solvent with the liquid to be extracted. The three compartments of the flask are continuous with no barriers. The bottom open portion of the flask is then attached to and sealed with the fitted plug (13) as described above (Figure 1). The height of the conduit (16) is adjusted by a sliding movement to the lower graduated
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Figure 1. Detailed view of the Karamian separatory funnel
mark of the component (11).The solvent layer can rapidly and quantitatively be removed from this compartment into another container or in atomic absorption spectrophotometric analyses, for example, the plastic capillary from the nebulizer of the atomic absorption unit can be dipped directly into this organic phase of the flask through the stoppered joint (30). Alternatively, the liquid in the lower portion of the flask can be completely removed as described previously
Figure 2. Three-chambered flask structure of the Kararnian separatory funnel
and the flask refilled with an additional volume of solution. This extraction can be repeated and the concentration of the substances being sought in the organic solvent can be increased. In abstract, the upper layer can easily be removed by lowering or raising the conduit, while the lower layer is removed by aligning the drain holes in the plug. The separatory devices of this invention may be constructed using many suitable materials. Preferably, the flask container and the stopcock portions of the funnel should be made from glass and the conduit and plug attachments from Teflon (DuPont). U.S.Patent 3,713,778 was issued for this device on January 30, 1973, and a prototype has been manufactured by Arthur H. Thomas Company, Vine Street at Third Avenue, Philadelphia, Pa. 19105. Received for review April 10, 1973. Accepted July 6, 1973. Mention of commercial concerns does not constitute endorsement by the National Institutes of Health.
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