US 3397965 A
Description (OCR text may contain errors)
Aug. 20, 1968 R. R. BERUEFFY GAS ANALYSIS UNIT Filed June 17, 1965 0 Z i a z 0 Z i: z A M, M S
INVENTOR. ROBERT R. EL-KUEFFV BY 0M 1L 4770/?NE V Filed June 17, 1965, Ser. No. 464,727 9 Claims. (Cl. 23-230) This invention relates to the quantitative analysis of components in chemical Specimens and more particularly to the quantitative analysis of components in physiological specimens.
The quantitative analysis of a component in a specimen is a task which is largely reserved for the laboratory chemist. Usually, only he has the equipment and facilities and the familiarization with the analysis to run it. It is, however, time consuming and expensive to call on the laboratory chemist for many analyses and often, too, there is the risk that some change will occur in the specimen While it is in transit. As a consequence, in the fields of clinical chemistry, toxicology, and criminal investigation in particular, a means and technique have been sought whereby the analysis can be run at or near to the specimens point of origin, through the use of equipment that is directly available to the technician or investigator taking the specimen.
One object of my invention is to provide a means and technique whereby this can be accomplished with respect to components that are convertible to the gaseous or vaporousstate. Another object is to provide such a mean-s and technique wherein the analytic procedure is greatly simplified over conventional laboratory and field procedures, both as to the equipment required and as to the steps of the procedure. A still further object is to provide such a means and technique wherein the gaseous or vaporous form of the component is induced to produce a measurable chemical change in a reagent that can be compared with a standard for purposes of the quantiative determination. Other objects include accomplishing this in a single integrated unit, preferably a throw-away unit, which can be easily and cheaply packaged for distribution to hospitals, industrial toxicologists, criminal investigatory agencies, and the like, through ordinary chan-. nels of commerce.
These and still further objects and advantages are realized by a means and technique of my invention wherein the component to be analyzed quantitatively, is separated from the specimen by converting it into independent gaseons and/or vaporous form, i.e., into volatilized form and then induced to flow into one end of an open-ended tube having a liquid reagent therein that is suspended in a free physical state across the bore ,of the tube, and which contains asubstance that is reactive quantitatively with the gas and/ or vapor andpresentinan amount in excess of the maximum stoichiometric amount expected for the specimen. The tube is thereafter centrifuged to displace the liquid portion of the reacted reagent into a receptacle, and the displaced liquid portion is compared with a standard derived by passing a known quantity of the component through the same steps. The component may be converted into the gaseous and/ or vaporous form and induced to flow into the tube, by the application of heat, by chemical reagents, or by a combination of heat and chemical reagents. Ordinarily I prefer to compare the displaced liquid portion with the standard spectrophotometrically.
The foregoing means and technique are based to an extent on my discovery and use of the fact that the liquid reagent can be maintained in a state of free physical suspension across the bore of the tube by engaging a packing of fine inert discrete material in the bore and allowing the reagent to diffuse through the packing until it is suspended on the same by virtue of interfacial tension ited States Patent between the liquid and the packing. When the tube is centrifuged the equilibrium condition in the packing is disturbed and the liquid is displaced and discharged out one end of the tube. My preferred practice is to incorporate the tube into a small unit consisting further of closed container means that are detachably connected to the tube, and in communication with one end thereof, to hold the specimen while the component is separated from the same and the gas and/ or vapor is induced to flow into the end of the tube- Such a unit is illustrated in the attached drawing wherein FIGURE 1 is a perspective view of the same;
FIGURE 2 is a cross sectional .view of the unit disposed in a hot water immersion bath; and
FIGURE 3 is a schematic illustration of the centrifugation step showing the means essential to displacing the liquid portion of the reacted reagent into a receptacle.
Referring first to FIGURE 1 it will be seen that the unit comprises a small four-sided glass jar 2 containing a pelleted lead ballast material 4 intended to lower the center of gravity of the unit and to increase the reaction area in the chamber 6 of the jar. The ballast also reduces the heat loss from the chamber. The neck 8 of the jar is threaded to receive a plastic cap 10 which has internal threads and a center opening 12 in its top from about the edge of which a columnar plastic tube 14 extends in the upward direction. The tube is integral with the cap and open-ended so that the chamber can communicate with the atmosphere along the bore 16 of the tube.
Engaged in the bore of the tube is a packing 18 of glass wool which provides a medium for the free physical suspension of a liquid reagent 20 containing a substance which is reactive quantitatively with the gas and/ or vapor evolved from the specimen 22 in the chamber. In this instance the gas and/0r vapor is driven off and induced to flow into the tube by immersing the unit in a hot water bath 24 in the manner of FIGURE 2. When its separation is complete, as evidenced, for example, by an expected color change in the reagent, the unit is removed from the bath, the cap and the jar are unscrewed from one another, and the tube 14 is inserted into a common test tube 26 carried in the harness 28 of a trunnion ring 30 of a centrifuge. As the centrifuge is operated, the harness, the test tube, and the tube-end of the cap are swung into a horizontal plane and rotated until the liquid portion of the reacted reagent is displaced from the tube into the test tube. Thereupon, the cap is lifted out of the test tube and the latter in turn is removed from the harness for spectrophotometric comparison with a standard derived by passing a known quantity of the component through the same steps. The mode of carrying out such a comparison is well known and accordingly need not be explained in detail.
Numerous materials can be used for the packing, so long as the material is inert to the reaction and is finely divided, as in the case of particulate and filamentous mate rials. By finely divided I have in mind, for example, a packing of the order of 30050 mesh, although it will be understood that the necessary mesh is a functional consideration and will vary from one unit to another, depending on the specimen and component to be analyzed. Other suitable materials include other forms of vitreous materials, such as ground :glass, siliceous materials such as silica dust, and plastic materials such as ground Teflon or polyethylene.
The liquid reagent will vary, of course, from one analysis to another, as may the nature of the liquid portion of the reacted reagent which is displaced from the tube; there being instances when this portion is the unreacted reagent material only, instances when it is the reacted material only, instances when it is the reacted material only, and instances when it is the whole of the reagent material.
EXAMPLE I As an example of my method a glass wool packing of approximately 50 mesh was charged with 71 cc. of acidified potassium dichromate in a unit of the nature of FIG- URE 1 containing a cc. specimen of human blood. The unit was immersed in a hot water bath to evaporate ethyl alcohol from the specimen, and the vapor was forced into the tube to reduce the chromium +6 of the reagent to chromium +3. Thereafter, the solution was centrifuged into a common test tube to which was added 1 cc. of 10% potassium iodide solution. The color resulting from the liberation of free iodine by the remaining chromium +6 provided a basis for comparing the sample spectrophotometrically with a standard made up beforehand.
EXAMPLE II As a further example 1 cc. of 1 normal sulphuric acid was added to a specimen of blood plasma in a 50 mesh glass wool unit charged with a solution of barium hydroxide having sufiicient mil-equivalent/liter of barium ion to precipitate carbon dioxide in the specimen as barium carbonate. The unreacted barium ion was centrifuged into a common test tube and dilute sulphuric acid was added to precipitate the barium as barium sulphate. The barium sulphate concentration was then read in a spectrophotometer and the reading was compared with a determination made from a standard solution of bicarbonate carried out in the same manner.
EXAMPLE III Dilute sulphuric acid was added to a third blood specimen in a unit charged with acidified palladium chloride. Carbon monoxide evolved from the specimen reduced the palladium ion to metallic palladium, a solid, and the unreacted liquid palladium chloride was centrifuged out, mixed with dilute potassium iodide and compared with a sample in the manner of Example I.
Other determinations which can he made include the determination of ammonia by charging the packing with an acid or Nesslers solution and releasing the ammonia by the addition of a base or the application of heat. A determination of oxygen content can be made by charging the packing with pyrogallol or some other reagent which reacts with gaseous oxygen and releasing the oxygen from the specimen by the addition of a ferricyanide or other suitable oxygen-releasing agent. It is also apparent that the various agents mentioned are only illustrative and that quantitative determinations of numerous other gaseous or vaporous components, such as cyanide, can be made in the same manner as in the examples.
I claim as my invention:
1. A method of making a quantitative determination of a component in a chemical specimen of generally known characteristics, comprising separating the component from the specimen by converting it into independent volatilized form, inducing the thus volatilized component to flow into one end of an open-ended tube having a liquid reagent therein that is suspended in a free physical state across the bore of the tube, said reagent containing a substance which is reactive quantitatively with the thus volatilized component, and which is present in an amount in excess of the maximum stoichiometric amount expected for the specimen, centrifuging the tube to displace the liquid portion of the reacted reagent into a receptacle, and comparing the displaced liquid portion with a standard derived by passing a known quantity of the component through the same steps.
2. The method according to claim 1 wherein the component is converted into the volatilized form by the application of heat to the specimen.
3. The method according to claim 1 wherein the component is converted into the volatilized form by the addition of a chemical reagent to the specimen.
4. The method according to claim 1 wherein the displaced liquid portion is compared with the standard spectrophotometrically.
5. In a gas analysis unit for making a quantitative determination of a volatilized component in a chemical specimen, an open-ended tube having a packing of fine inert discrete material engaged in the bore thereof, said tube being capable of holding a reagent therein, for reaction with the volatilized component, and closed chemical specimen container means detachably connected to, and in open communication with, one end of the tube.
6. A gas analysis unit according to claim 5 wherein the packing is of glass wool.
7. A gas analysis unit according to claim 5 wherein the container means takes the form of a glass jar whose neck is threadedly engaged with the end of the tube.
8. A gas analysis unit according to claim 5 wherein the packing is of 300- mesh.
9. A gas analysis unit for use in the quantitative analysis of a volatizable component in a chemical specimen, comprising an open-ended tube having a packing of fine inert discrete material engaged in the bore thereof, and a liquid reagent therein which is diffused through the packing and suspended in a free physical state on the same, by virtue of interfacial tension between the liquid and the packing; and closed chemical specimen container means detachably connected to, and in open communication with, the tube.
References Cited UNITED STATES PATENTS 3,215,500 11/1965 Bittner 23-230 X 3,223,488 12/ 1965 Luckey 23--232 X 3,249,403 5/1966 Bochinski et al 23-232 X MORRIS O. WOLK, Primary Examiner.
R. M. REESE, Assistant Examiner.