US 3449080 A
Description (OCR text may contain errors)
United States Patent 3,449,080 DEVICE FOR DETERMINING SODIUM OR CHLO- RIDE CONCENTRATION IN BODY FLUIDS Warren R. Edwards, Somerset, N.J., assignor to Johnson & Johnson, a corporation of New Jersey No Drawing. Filed Oct. 29, 1964, Ser. No. 407,514 7, Int. Cl. G01n 31/04, 33/16 US. Cl. 23-230 6 Claims ABSTRACT OF THE DISCLOSURE A diagnostic device consisting of a bibulous paper impregnated with a weakly basic or a weakly acidic ion exchange resin and a pH indicator for use in making rapid determination of the level of chloride or sodium, respectively, in body fluids.
This invention relates to diagnostic devices and more particularly to devices and methods for rapidly determining the level of an electrolyte in body fluids for diagnostic purposes.
Body fluids, such as blood, urine, sweat, cerebrospinal fluid, saliva and other general tissue fluids contain electrolytes such as sodium, chloride, magnesium, potassium, phosphorous and calcium. In normal healthy individuals, it has been observed that the levels or concentrations of such electrolytes in body fluids fall within certain ranges which are indicative of the state of health and well-being of an individual. Electrolyte levels which are above or below such ranges are suggestive that an individual may be suffering from some disease or disorder.
Gibson & Cooke report (Pediatrics, March 1959, p. 545) that the level of chloride in sweat induced by iontophoresis of pilocarpine nitrate in patients acting as controls was found to be in a concentration of no more than about 60 meq./l., while the sweat so induced in individuals suffering from cystic fibrosis of the pancreas was found to have a chloride concentration of 80 or more meq./l. In the Journal of Pediatrics, June 1963, p. 855, Gibson & diSant Agnese report that children whose sweat sodium or chloride is above 60 meq./l. are almost invariably afllicted with cystic fibrosis of the pancreas (if Addisons disease is ruled out) while normal, healthy children whose sweat sodium or chloride concentration is below 50 meq./l. are almost certainly free from this disorder. Lieberman and Kellog have reported (The American Journal of the Medical Sciences, November 1963, 59/537) that in the pediatric age group, the level of sweat sodium chloride is consistently four to five times higher in patients suffering from cystic fibrosis than the level in normal controls. The level of such electrolytes in body fluids other than sweat also deviate from the normal in such cases.
In addition, individuals suffering from such disorders as peptic ulcer, arthritis, pneumococcus meningitis and pyrogenic meningitis have also been found to have electrolyte levels in body fluids which deviate from those of healthy, normal individuals. For example, studies on the level of sodium in the gastric secretion of normal individuals have established a mean of about 113 meq./l., while in the case of individuals suffering from peptic ulcer it has been found to be about 56 meq./l. Arthritic patients have been found to have a mean sodium concentration in saliva secretion of about 20.6 meq./l., while the mean concentration in normal individuals is about 44 meq./l. Individuals suffering from pneumococcus meningitis have a mean chloride concentration in cerebrospinal fluid of about 95 meq./l., as compared to a mean concentration in normal individuals of about 120 meq./l. Thus, the level of electrolytes in body fluids of individuals suffering from 3,449,080 Patented June 10, 1969 a disease or disorder may be higher or lower than those in normal individuals and may range from wide to narrow deviations.
To institute promptly proper corrective measures for a disease or disorder, early diagnosis is essential. The fact that the electrolyte levels in body fluids of individuals suffering from a disease or disorder vary from the mean or average has proven useful in this connection. It has led to the development of devices and techniques for measuring the electrolyte levels for such purposes. Such developments include devices for measuring the electric conductivity of sweat, as reported by Shwackman, Dunham and Phillips (Pediatrics, July 1963, p. the use of a sodium electrode to measure sodium activity at the skin surface, as reported by Goldbloom and Sekelj (New England Journal of Medicine, Dec. 19, 1963, p. 1349); the use of pilocarpine iontophoresis, as reported by Lieberman and Kellog (American Journal of Medical Sciences, November 1963); and the use of filter paper containing silver nitrate and potassium chromate for determining the amount of chloride in hand sweat, as reported by Knights, Bush & Schroeder (Journal of American Medical Association, vol. 169, No. 12 (1959).
While such devices and techniques developed heretofore have proven useful as diagnostic aids, they have many disadvantages. Some involve complicated, time consuming devices and methods which require the use of complex laboratory techniques and highly trained technicians. Many are expensive, while others lack stability. A particularly common disadvantage is that they are uneconomical and are not adaptable to mass screening of individuals or patients. There has thus been long sought a suitable diagnostic device and technique for measuring the electrolyte level in body fluid which is simple, inexpensive, easily used, which has good stability, and which can be used rapidly to mass screen individuals in hospitals, clinics, and in the physicians ofiice. This invention provides such a device and technique.
In accordance with this invention, there is provided a device for measuring the level of electrolyte in body fluid for diagnostic purposes which comprises a carrier containing a polymeric material having ion exchange characteristics which is capable of exchanging ions with the electrolyte whose level is to be measured, and a material which is color responsive to the extent of the ion exchange, thus reflecting the level of the electrolyte in the body fluid. In a more specific form, the invention comprises a diagnostic device for measuring the level of electrolyte in body fluid which includes a carrier absorptive to the body fluid and having incorporated therein a polymeric ion exchange material which is insoluble in the body fluid and which is capable of effecting a pH change by quantitative ion exchange with the electrolyte whose level is to be determined, the extent of which is visually determined by means of an indicator which is color responsive to the change in pH resulting from the ion exchange.
By way of example, body sweat contains sodium chlo ride which ionizes into sodium and chloride ions. In the presence of a weakly basic polymeric ion exchange material which has a greater affinity for chloride ions, the chloride ions replace hydroxide ions available in the ion exchange material. The extent of ion exchange is visually determinable by a color developed in an indicator associated with the ion exchange material.
The following is an example of a device embodying the present invention which is useful in diagnosing cystic fibrosis of the pancreas, particularly in the case of children. It is to be understood, however, that the example is for illustrative purposes and is not to be construed as limiting the invention.
A carrier in the form of bibulous paper one inch square made from high quality alpha-cellulose pulp is impregnated with a polymeric ion exchange resin which is in the form of a Weak base, i. e., an anion exchanger. Papers of this type are disclosed in U. S. Patent No. 2,798,850 and are available from H. Reeve Angel & Co., Inc., under the designation WB2. They contain from about 45 to 50% by weight of resin. The polymeric ion exchange resin is Amberlite IR-4B which is available from Rohm & Haas. It is a high molecular weight copolymer having a combination of primary and secondary amine groups and is supplied in the hydroxide form. It is similar in basicity to ammonium hydroxide, has an approximate exchange capacity of 4.8-4.2 meq./gm. and functions in a pH range of from about to 9.
The ion exchange resin is preferably incorporated into the paper during the paper-making process so that it is homogeneously distributed throughout the paper and so that it will be retained in the paper and will not readily separate or dust off. It may, however, be applied to the paper in other ways, as by coating, by spraying, or by passing the paper through a bath containing the polymeric ion exchange resin.
One to two drops of a /2 solution of phenolphthalein in 95% ethanol is applied to the paper carrier containing the ion exchange resin and it is then dried. The carrier is placed centrally upon the adhesive side of a piece of transparent pressure sensitive adhesive tape two inches square which acts as a backing strip and it and the adhesive tape are then covered with a removable paper facing sheet, such as a silicone-coated paper, to provide a completed article ready for use. The device so prepared may be used as a diagnostic device in determining the level of chloride in body sweat in connection with diagnoses of cystic fibrosis of the pancreas.
The device may be used for such purpose in the following manner. The forehead of a child to be tested is washed with distilled water and dried. The forehead is particularly suitable as a test area because sweat is readily and rapidly formed on the forehead, especially when the child is active as, for example, when it is being nursed or fed. The test device is desirably applied to the forehead before feeding begins. To apply the device, the facing strip is removed from the adhesive surface of the backing strip and the device is placed into adhesive contact with the forehead with the paper carrier in contact with the skin. When the carrier becomes wet, or a color change is noted, the device is removed and the color which has developed is compared with a previously prepared color comparison chart to determine the level of the chloride in the sweat. Alternatively, a drop of the sweat may be removed from the forehead; e.g, with a wooden tongue depresser, and placed upon the paper carrier. After a period of time, such as one minute, the color developed is compared with the chart.
A color comparison chart may be prepared as follows. A one inch by six inch strip of the carrier paper impregnated with the ion exchange resin (i.e., H. Reeve Angel & Co., Inc., WB2 paper impregnated with the Amberlite IR-4B resin) has placed upon its surface in five spaced areas one drop of /2% phenolphthalein in 95 ethanol. The paper is then dried. On the first area to which the phenolphthalein was applied there is placed a drop of a sodium chloride solution containing 25 meq./l. of chloride; on the next area, one drop of a sodium chloride solution containing 50 meq./l. of chloride; on the next, one drop of a solution containing 80 meq./l. of chloride; on the next, one drop of a solution containing 120 meq./l. of chloride and on the last area, one drop of a solution containing 220 meq./l. of chloride. The paper is then permitted to dry. A color will develop in each of the five areas to which the drops of phenolphthalein and the drops of the solution containing different concentrations of chloride have been applied. The color will vary from light pink in the area to which one drop of the solution containing 25 meq./l. of chloride has been added to dark pink in the area in which one drop of the solution containing 220 meq./l. of chloride has been added. Each of the colored areas so formed may be identified by placing above or below the area the number which corresponds to the concentration of the chloride in the solution applied to the area. The paper may then be covered with a clear, impervious facing strip, such as a strip of transparent adhesive tape, which serves as a protective covering.
The test device which has been removed from the surface of the forehead of the person being tested will have developed a color which is related to the level of chloride in the sweat. This color is compared with the various colored areas on the color comparison chart to determine the level of chloride in the sweat. In the case of cystic fibrosis, it has been determined that the sweat of a normal child has a mean chloride ion concentration of approximately 25 meq./l. This concentration of chloride ion will produce a light pink color on the patch. The sweat of a child afflicted with cystic fibrosis of the pancreas has a mean chloride ion concentration of approximately meq./l. which produces a dark pink to light red color. By comparing the depth or shade of the color of the test device with the various colored areas on the color comparison chart, the level of chloride ion in the sweat tested can be rapidly determined. If the color produced in the test device is of a deeper shade of pink than the color of the area in the color comparison chart where one drop of the solution containing 50 meq./l. of chloride was placed, cystic fibrosis of the pancreas may be present. Since the color develops quickly, the entire test procedure requires only a few minutes. If the results are positive, further substantiating tests using the more elaborate known procedures for diagnosing cystic fibrosis of the pancreas may then be conducted.
Instead of applying the test device to the forehead of the body in the manner described above, it may be applied to the sole of the foot or the back. Alternatively, some of the sweat can be removed from such surfaces and applied to the test device. However, the level of sodium chloride may vary in different parts of the body and in different body fluids. For example, sweat obtained from the back of normal children has been found to have a mean level of about from about 35 meq./l., as compared to a mean level of about meq./l. in children afflicted with cystic fibrosis. The saliva of normal children has been found to have a mean level of about 10.2 meq./ l. for sodium and 13.5 meq./l. for chloride, as compared to a level of 23.5 meq./l. of sodium and 18.8 meq./ l. of chloride in children having cystic fibrosis of the pancreas. Therefore, such levels and ranges in levels should be taken into consideration in preparing devices incorporating the invention. Preferably, the sweat or body fluid used in the test should be taken from the portion of the body from which it is readily available and which exhibits the greatest difference in the electrolyte level between the mean level in normal healthy individuals and the mean level of individuals afficited with the disease or disorder being diagnosed.
Although the level of sodium and chloride in tears and saliva of individuals afilicted with cystic fibrosis of the pancreas also deviates fromthe normal level, it is preferable to use body sweat in such diagnosis because the level of these electrolytes in sweat is more uniform and the deviation from the normal level greater, thereby making its measurement more positive, whereas the deviation of the level of the electrolytes in tears and saliva is not so distinct.
Satisfactory results are obtained with minimal quantities of sweat since such quantities are usually sufficient to produce a color change in the test device. It is necessary, however, that the surface of the body on which the device is applied or from which the sweat is removed for testing be washed and then dried before testing to avoid false readings which may occur if excessive amounts of sodium chloride are present on the skin surface due to the evaporation of water from the sweat. The test may be conducted rapidly and the results evaluated quickly. It lends '5 itself to mass screening techniques which can be conducted easily and economically.
The color occurs in the above described test device in the following manner. The ion exchange resin is a weak base having available hydroxide ions and a greater aflinity for chloride ions than for the hydroxide ions. When the sweat comes in contact with the resin the hydroxide ions which are released in exchange for the chloride ions cause a change in the pH of the fluid system. The change in pH is directly related to the number of hydroxide ions which have been released which in turn is related to the number of chloride ions in the sweat. The change in color of the phenolphthalein indicator reflects the change.
Test devices for measuring the level of other electrolytes in other body fluids may be prepared in accordance with the invention. A sutiable test device for determining the level of the cation sodium in cerebrospinal fluid as an aid in diagnosing pneumococcus meningitis may be prepared as follows. A carrier in the form of bibulous paper one inch square made from a high quality alpha-cellulose pulp is impregnated with a polymeric ion exchange resin which is in the form of weak acid, i.e., a cation exchanger. Papers of this type are available from H. Reeve Angel and Co., Inc. under the designation WA-2 and are also described in US. Patent No. 2,789,850. The polymeric ion exchange resin is Amberlite IRC-SO which is available from Rohm' & Haas. It is a high molecular weight copolymer which has carboxyl groups as the functional part of its structure and is supplied in the hydrogen form. Its acidity is similar to acetic acid and it has an approximate exchange capacity of 4.6 to 5.0 meq./ gm. It functions in a pH range of from about to about 14. The ion exchange resin may be incorporated into the paper in the manner described in the preceding example to provide from about 45 to 50 percent by weight of the resin.
To select the proper indicator to be used in this system comprising this particular ion exchange material and cerebrospinal fluid, the pH produced on the resin paper by cerebrospinal fluid is first established. To determine the pH, a small piece of pHydrion indicator paper, e. g., paper having a range of from 2 to 10, is placed on a piece of the ion exchange paper. One drop of cerebrospinal fluid from a normal, healthy individual is then placed upon the pHydrion paper. In so placing the fluid, the indicator in the pHydrion paper is leached out onto the ion exchange paper. The ion exchange paper is then examined for color to determine the pH of the system in accordance with the usual method of determining pH with pHydrion papers. In the case of cerebrospinal fluid, a greenish-gray color is produced, indicating that the pH of the system is about 5. A suitable indicator for use in this pH range 1s methyl orange because its range in color change lncludes this pH and because its change in color around this pH is visually observable for small increments of pH change.
Having selected the indicator, two drops (2% of methyl orange in 95% ethanol) are applied to the 1011 exchange paper containing Amberlite IRC-50 and the paper is then permitted to dry to complete the test device. If desired the paper carrier so prepared may be secured to an adhesive backing and covered with a removable facing sheet as described in the preceding example.
The color comparison chart for use with such a device is prepared as follows. A one inch by six inch strip of the carrier paper impregnated with the ion exchange resin has applied to its surface in three spaced areas one or two drops of the methyl orange indicator and the paper 1s then dried. Since the level of sodium in cerebrospinal fluid of normal healthy individuals is about 120 meq./l., while the level in individuals suffering from pneumococcus meningitis is about 95 meq./l. on the average, 1.e., is lower than the normal level, there is prepared a series of solutions of varying concentrations of sodium chloride including a solution containing 120 meq./l. of sodium and solutions whose concentrations of sodium are below this concentration. On the first area to which the methyl orange indicator was placed, there is applied, for example, a drop of a sodium chloride solution containing meq./l. of sodium; on the next area, one drop of a sodium chloride solution containing meq./l. of sodium; on the next, one drop of a sodium chloride solution containing meq./l. of sodium. The paper is allowed to dry. A color change will occur in each of the areas to which the methyl orange indicator and the drops of the solutions containing different concentrations of sodium have been applied. The color in the area to which the one drop of the solution containing the 80 meq./l. of sodium was applied will be orange; the color in the area to which the one drop of the solution containing 100 meq./l. of sodium was placed will be orange to pink; and the color of the area to which one drop of the solution containing 120 meq./l. of sodium was applied will be pink. Thus, by applying to the test device a drop of cerebrospinal fluid whose level of sodium ion is to be measured, a color will develop which can be compared with the various colored areas in the color comparison chart to determine the level of sodium in the fluid.
If it is desired to measure the level of sodium instead of chloride in body sweat to diagnose cystic fibrosis of the pancreas, the paper designated as WA-2 obtainable from H. Reeve Angel & Company, Inc. and containing the Weak acid type polymeric ion exchange resin, Amberlite IRC-SO, may be used. A suitable indicator is methyl orange. In preparing such a device, a sodium color comparison chart would also be prepared.
It is also possible to measure the level of chloride in cerebrospinal fluid, instead of sodium, by using the paper obtainable from H. Reeve Angel & Company, Inc. under the designation WB-Z and containing phenolphthalein as the color responsive material. In this form of the invention, a color comparison chart containing varying concentrations of chloride would be prepared.
The particular polymeric ion exchange material selected is determined by the electrolyte whose level is to be measured. There should also be considered the amount of the electrolyte present in the body fluid being tested, and the pH of the system produced when the particular body fluid to be tested is applied to the ion exchange material. In general the following procedure may be followed to provide a test device in accordance with the invention for measuring the level of electrolyte in a body fluid.
First, the type of electrolyte and its concentration in the body fluid to be tested is determined. Normally, one to two drops of the body fluid are adequate for test purposes. On this basis, the ion exchange material to be used is selected. For example, if it is desired to provide a test device for measuring chloride in sweat, the polymeric ion exchange material selected is one which is weakly basic. To determine the pH of the system when the selected polymeric ion exchange material is used, pHydrion paper is placed on a piece of a carrier in the form of bibulous material impregnated with the polymeric ion exchange material. pHydrion is the trademark of the Micro-Essential Laboratories, Brooklyn, N.Y., for a line of pH indicator papers composed of a bibulous paper having impregnated therein a pH indicator. A drop of the body fluid to be tested is then placed on the pHydrion paper and the color produced in the carrier is noted. This establishes the pH of the system from which a suitable indicator which exhibits a change in color within the pH range of the system may then be selected. The indicator is preferably one which exhibits pronounced, observable color changes with changes in the level of electrolyte which is established in evaluating a particular electrolyte in a particular body fluid. Upon selecting the indicator, one or two drops are applied to the carrier impregnated with the polymeric ion exchange material to provide, after drying, the test device.
There is next determined the level in normal individuals of the electrolyte whose level is to be measured in the body fluid and the level of the electrolyte in the body fluid of individuals who are suffering from a disease or disorder, the presence or absence of which it is desired to diagnose with the test device. Such levels may be obtained from medical literature or by actual measurement. A series of solutions of the electrolyte are prepared in concentrations which include the level of the electrolyte in normal individuals and the level in individuals suffering from the disease or disorder to be diagnosed.
To prepare the color comparison chart to be used in connection with the test device, a piece of the carrier, e.g., 1" by 6" strip of bibulous paper, impregnated with the selected ion exchange material has applied to it in spaced areas one to two drops of the selected indicator and the carrier is then dried. One or two drops of the solution having the lowest concentration of the electrolyte is applied to the first area; one or two drops of the solu tion containing the next highest concentration is applied to the next area, and so on. After the color has developed in the areas, the color comparison chart is covered with a transparent material, such as a piece of transparent pressure sensitive tape to preserve the chart for continued use.
The preferred color responsive materials are indicators of the type which are well known in the art. The material used depends on the pH of the system which in turn is determined by the particular ion exchange material used and the body fluid being tested. Indicators which are effective in various pH ranges are readily available and once the pH of the system is determined, a suitable indicator may then be selected. Different indicators may be used in the same device. For example, instead of using methyl orange as the indicator, tetraiodophenolsulfonthalein may be used since its pH range of effectiveness includes the pH range of effectiveness of methyl orange. Mixed indicators and other color responsive materials may be used if desired.
Various polymeric ion exchange materials may be used to provide a test device incorporating the invention. They may be cation or anion exchangers, depending upon the particular electrolyte whose level is to be measured. The weakly acidic and weakly basic types of polymeric ion exchange materials will generally be found to be most suitable in view of the quantities of electrolyte present in body fluids. In addition to such well-known types available from Rohm & Haas under the trade name Amberlite, there may be used naturally occurring ion exchange materials, such as alginic acid, pectin, carragheen, potato starch, corn starch, flour cellulose, wood, paper straw, casein, keratin, collagen, vermiculite, kaolinite and analcite. Other suitable synthetic ion exchange materials include the synthetic zeolites, phenolic resins, and triethylene tetramine (TETA). The synthetic types are preferred because of their uniformity and the ease by which they may be incorporated into the carrier. V
In addition to Amberlite IR-4B, which is preferred in test devices incorporating the invention for evaluating the level of chloride in body fluids such as sweat, spinal fluid and blood serum, other suitable weakly acidic materials having ion exchange characteristics include diethylaminoethyl cellulose, aminoethyl'cellulose and Ecteola BT81, a cellulose type ion exchange material available from Scientifica Company. Another suitable weakly acidic ion exchange material useful for measuring the level of the electrolyte sodium is carboxymethyl cellulose. This material may be obtained with different degrees of substitution to vary its ion exchange capacity.
The polymeric ion exchange material selected is of the type which is desirably insoluble in the body fluid to be tested. The amount of the ion exchange material incorporated in the carrier should have sufficient exchange capacity to react with the electrolyte in the body fluid applied to the test device so that an accurate determination is obtained.
The carrier desirably has absorptive properties to permit the indicator and the body fluid applied to the carrier during the test to be evenly distributed so that a uniform color will be developed. Bibulous paper has been found especially suitable and is preferred. However, there may be used other materials such as cotton, wool, synthetic fibers, synthetic sponges, and the like which absorb or otherwise pick up the body fluid and on which or in which the indicator and polymeric ion exchange material can be evenly distributed.
In the preferred form of the invention, the carrier is associated with an adhesive backing strip to provide a device similar to an adhesive bandage so that it may be adhesively applied to a body surface and then removed for evaluation. This form of the invention is especially useful where the body fluid being tested is sweat. However, an adhesive backing strip is not required to test such body fluids as blood serum and cerebrospinal fluids. Such fluids may be collected by conventional means and one to two drops applied to the test device, which is in the form of the carrier containing the polymeric ion exchange material and the indicator.
If a large group of individuals are to be tested at one time, thereby making difficult prompt evaluation of the color developed, in that form of the invention in which the carrier is mounted on an adhesive backing, it is perferred that the backing be impervious so that incorrect readings due to a build up in the level of electrolyte caused by evaporation of the body fluid are minimized.
Devices prepared in accordance with the invention provide a rapid, effect means for determining the level of electrolytes in body fluids for diagnostic purposes. The devices are economical to manufacture and their use does not require highly skilled personnel.
While the invention has been described in connection with various illustrative embodiments, it is to be understood that the invention is not limited thereto and that changes and modifications may be made while still remaining within its spirit and scope.
What is claimed is:
1. A method for determining the level of chloride in body sweat for diagnosing cystic fibrosis of the pancreas which comprises contacting body sweat with a carrier containing a weakly basic polymeric material having ion exchange characteristics and which is capable of effecting a pH change by ion exchange with said chloride, and an indicator which is color responsive to said pH change, permitting said color to develop, and comparing said color with colors indicative of known amounts of chloride.
2. A method for determining the level of sodium in body sweat, for diagnosing cystic fibrosis of the pancreas which compirses contacting body sweat with a carrier containing a weakly acidic polymeric material having ion exchange characteristics and which is capable of effecting a pH change by ion exchange with said sodium, and an indicator which is color responsive to said pH change, permitting said color to develop, and comparing said color with colors indicative of known amounts of sodium.
3. A device for rapidly determining the level of chloride in body fluid for diagnosis of cystic fibrosis of the pancreas comprising a carrier containing a polymeric material having ion exchange characteristics, said polymeric material being weakly basic and being capable of effecting a pH change by ion exchange with said chloride, and an indicator associated with said polymeric material which is color responsive to said pH change.
4. A device for rapidly determining the level of sodium in body fluid for diagnosis of cystic fibrosis of the pancreas comprising a carrier containing a polymeric material having ion exchange characteristics, said polymeric material being weakly acidic and being capable of effecting a pH change by ion exchange with said sodium, and an indicator associated with said polymeric material which is color responsive to said pH change.
5. A device for rapidly determining the level of chloride in body sweat for diagnosing cystic fibrosis of the pancreas comprising an adhesive backing, a carrier absorptive to said body sweat adhered to the adhesive side of said backing and having marginal edges terminating inwardly of marginal edges of said backing, a removable facing covering said carrier, said carrier containing a polymeric ion exchange resin which is insoluble in body sweat, said polymeric material being weakly basic and being capable of effecting a pH change by ion exchange with said chloride, and an indicator associated with said polymeric material which is color responsive to said pH change.
6. A device in accordance with claim 5 wherein said indicator is phenolphthalein.
References Cited UNITED STATES PATENTS 2,798,850 7/1957 Voigtman et al 210502 2,935,194
3,212,495 10/1965 Osbourn et a1. 1282 5/1960 Tomkin 210 2s XR 20 5/1964 Canada. 2/ 1951 Great Britain.
OTHER REFERENCES Weeks et al., Sweat Analysis in Fibrocystic Disease, Chem. Abs., vol. 52, p. 11243, July 1958.
Calmon et al., Ion Exchangers in Organic and Biochemistry, pp. 434, 469, 490, Interscience Publisher Inc., N.Y., 1957.
Knights et al., Journal of the American Medical AssociatiOn, vol. 169, pp. 1279-80 (March 21, 1959).
Percival, R. W., Journal of the Society of Cosmetic Chemists, v01. 13, pp. 291-299 (August 1962).
MORRIS O. WOLK, Primary Examiner.
ELLIOTT A. KATZ, Assistant Examiner.
U.S. Cl. X.R.