CA1217698A - Fluid absorbent quantitative test device - Google Patents
Fluid absorbent quantitative test deviceInfo
- Publication number
- CA1217698A CA1217698A CA000419172A CA419172A CA1217698A CA 1217698 A CA1217698 A CA 1217698A CA 000419172 A CA000419172 A CA 000419172A CA 419172 A CA419172 A CA 419172A CA 1217698 A CA1217698 A CA 1217698A
- Authority
- CA
- Canada
- Prior art keywords
- reaction area
- sweat
- absorbent
- silver
- area
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/48—Biological material, e.g. blood, urine; Haemocytometers
- G01N33/50—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing
- G01N33/84—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing involving inorganic compounds or pH
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/42—Detecting, measuring or recording for evaluating the gastrointestinal, the endocrine or the exocrine systems
- A61B5/4261—Evaluating exocrine secretion production
- A61B5/4266—Evaluating exocrine secretion production sweat secretion
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/48—Biological material, e.g. blood, urine; Haemocytometers
- G01N33/50—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing
- G01N33/52—Use of compounds or compositions for colorimetric, spectrophotometric or fluorometric investigation, e.g. use of reagent paper and including single- and multilayer analytical elements
- G01N33/525—Multi-layer analytical elements
- G01N33/526—Multi-layer analytical elements the element being adapted for a specific analyte
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T436/00—Chemistry: analytical and immunological testing
- Y10T436/19—Halogen containing
- Y10T436/193333—In aqueous solution
Abstract
FLUID ABSORBENT QUANTITATIVE TEST DEVICE
Abstract An absorbent quantitative test device in the form of a flat patch. When placed on the skin of a subject, the device collects a fixed volume of sweat. It is particularly intended to be used in screen testing for cystic fibrosis by measuring the chloride level in sweat and providing a visual indication when the level is in excess of a predetermined concentration. A fill tab indicator undergoes a color change when the fixed volume of sweat has been collected signifying comple-tion of the test. The device includes two concentric circular reaction areas of chemically treated absorbent paper or the like. The sweat sample is introduced into the device at the center of the first or inner circular reaction area which contains a chemical composition capable of reacting with all chloride in the sweat sample below a predetermined concentration value to screen out that amount of chloride. A second or outer ring-shaped reaction area contains a chemical com-position which indicates a color change for any chloride reaching it in excess of the predetermined concentration value. The color change in the outer ring-shaped portion thereby provides a quantitative indication of the presence of a concentration of chloride in the subject's sweat in excess of the prede-termined concentration level.
Abstract An absorbent quantitative test device in the form of a flat patch. When placed on the skin of a subject, the device collects a fixed volume of sweat. It is particularly intended to be used in screen testing for cystic fibrosis by measuring the chloride level in sweat and providing a visual indication when the level is in excess of a predetermined concentration. A fill tab indicator undergoes a color change when the fixed volume of sweat has been collected signifying comple-tion of the test. The device includes two concentric circular reaction areas of chemically treated absorbent paper or the like. The sweat sample is introduced into the device at the center of the first or inner circular reaction area which contains a chemical composition capable of reacting with all chloride in the sweat sample below a predetermined concentration value to screen out that amount of chloride. A second or outer ring-shaped reaction area contains a chemical com-position which indicates a color change for any chloride reaching it in excess of the predetermined concentration value. The color change in the outer ring-shaped portion thereby provides a quantitative indication of the presence of a concentration of chloride in the subject's sweat in excess of the prede-termined concentration level.
Description
F _ D ADSORBENT QUANTITATIVE TEXT DEVICE
I. DESCRIPTION
Background of the Invention _ The test device of the invention is designed to perform a quantitative test on a given volume of a fluid to provide a visual indication when a certain substance is present in the fluid in an amount in excess of a predetermined amount.
In its preferred embodiment, the test device of -the invention is specifically directed -to a flat absorbent test patch device used in the screening of persons for cystic fibrosis. Consequently, the invention although of general applicability is described herein with spew cilia reference to wits use in screen testing for cystic fibrosis.
A simple screening -test is particularly needed for cystic fibrosis because of its high incidence in children. About 1 in 1000 to 1 in 1~00 infants are born with cystic fibrosis. Those having cystic fiber-skis exhibit high mortality. As recently as 1963 one-third of the deaths from cystic fibrosis occurred in the first year of life; two-thirds in the firs-t five years. The prognosis has recently improved due to early therapy and mortality has decreased to less than five percent in -the first year of life. A group half-life of over 20 years can be reasonably expected if treatment is early.
An abnormality which is used to i~lenti~y persons having mystic fibrosis is the unusually high chloride concentration in -their sweat. A sweat chloride con-cent ration significantly greater than normal is constantly present in all persons suffering from this disease.
D it Brief Summary of the Invention The device includes a first reaction area, prefer-ably in the form of a circular, preferably flat, absorb bent booty contacted by a surrounding, preferably flat, body of absorbent material which provides a second reaction area Preferably the surrounding body is circular or ring-shaped, although it may be any other shape. The outer or perimeter edge of the circular first reaction area contacts the entire inner edge of the ring-shaped second reaction area. A third reaction area, preferably in the shape of a small absorbent -tab or even a complete, surrounding, outer body which may be ring-shapecl also or any other shape, contacts the outer diameter of the second reaction area body. The purpose of the tab or its equivalent is to signify when the device is saturated with a given volume of the fluid being absorbed for test.
The absorbent bodies are enclosed in a preferably flat, fluid tight envelope which is transparent on a-t least one side at least in the outer reaction area and frill indication area. The opposite side contains an inlet opening aligned with the center of -the first reaction area for the introduction of the test fluid, such as sweat, thereto. This side also preferably carries a fluid collector which directs fluid to the inlet opening.
By selecting absorbent bodies of known absorbency and sizing them properly, the device is constructed and arranged to absorb a predetermined fixed volume of test fluid, such as sweat, to be evaluated for its content owe a substance, such as chloride, in excess of a prude-termined amount.
The inner circle or first reaction area is impregnated with a predetermined amount of a reactant which is provided in an amount sufficient to react with '.
. ' : ,, all of the substance contained in the absorbed -test fluid below a predetermined concentration value. The second reaction area or outer ring is also impregnated with a reactant which reacts with the substance in the test fluid also. However, since the fluid is intro-duped at the center of the first reaction area an must migrate radially there through before reaching the con-centric ring or second reaction area, the composition in the first reaction area reacts with any substance in the fluid below the predetermined value first. Any substance in the fluid in excess of the predetermined value is free to react with the reactant in the second reaction area only upon migration of the fluid and substance thereto. The reactant in the second reaction area is selected to provide color change upon exposure to or reaction with the excess substance thus visually indicating the fact that substance in excess of the predetermined amount is present in the test fluid.
The tab or its equivalent contains a reactant son-sitive to the fluid or a component thereof which undergoes a visual change in appearance upon its being reached by the migraine fluid to indicate -that -the first and second reaction areas are saturated with the fluid and a fixed volume thereof has been collected.
Brief Description of the Drawings Fig. 1 and 2 are -top and bottom views, respect lively, of a device according to the invention.
Fig. 3 is a schematic cross section taken through -the center of the device shown in Fig. 1.
Detailed Description of the Preferred Embodiment . .
The preferred embodiment of the device is intended for use in screen testing of subjects for cystic fiber-skis. It is constructed and arranged to absorb a 50Jdl ' test sample of sweat and to indicate the presence of chloride in the sweat in excess of a concentration of 45 my by providing a suitable, visually apparent, color change in the outer ring of the device. It may he modified to absorb differing amounts of sweat or other test fluids and to provide visual indication of various excess amounts of chloride or other fluid-contained substances. It is particularly useful for aqueous fluids having a dissolved salt to be determined.
Referring now to -the Figures, the device is comprised of an indicating layer generally indicated at 10 in Fig. 3. Indicating layer 10 includes inner circle 12, concentric ring 14 and tax 16 (seen in Fig.
1). Circle 12, ring 14 and tab 16 are of fluid absorb bent material such as filter paper or chromatography paper and are preferably substantially flat. These bodies are assembled such that circle 12 lies inside ring 14 with the outer edge of circle 12 contacting the inner diameter of ring 14. Tab 16 contacts the outer diameter or edge of ring 14 as shown. Upon assembly of the three absorbent bodies into their operating rota-tionship they are preferably subjected to pressure erg., 2600 lbs/sq inch to press them together. Tab 16 may be modified into various other shapes. For example, it I may be a third concentric ring, ring segment or other shaped surrounding body. Generally, it may be any shape or form so long as it contacts the outer edge of ring 14 and provides a visually apparent color change when contacted by the fluid being absorbed or a keenest-tent thereof.
The arrangement shown provides an indicating layer capable of absorbing a given volume of sweat depending on the size and weight of the absorbent paper selected and the overall size of the circular and ring-shaped bodies.
I
The various reaction areas may also be portio7ls of a single body of absorbent material impregnated with a suitable pattern of reactant materials.
Indicating layer 10 is enclosed in a non-absorbent fluid-tight envelope comprised of an overlaying transparent layer 18 and an underlying hacking layer 20. Layer 18 is transparent at least in a visually apparent portion of the second reaction area and of the fill indicator area. Layer 20 may be transparent also but not necessarily. suitable and most preferred material for layers 18 and 20 is transparent adhesive plastic tape such as polyester tape obtained from Bel-Art Products, Picnic, New Jersey which markets a tape identified as "Lab Label Protection Tape". This tape has been found to be somewhat resistant to cold flow, nonabsorbent and suitably transparent for use in forming the envelope in which indicating layer 10 is sealed between opposing adhesive surfaces of the tape aye and aye, respectively. Ire 20 is then provided wit a small central opening 21 aligned with the center of circle 12 to provide an inlet opening for sweat to gain access to indicating layer 10.
A sweat collector 22, preferably comprised of high density polyethylene non-woven sheet such a TYVEK~, obtained from the Paper Manufacturing Company of Philadelphia, is then attached to layer 20. Preferably this is accomplished by means of a double backed ache-size plastic tape 24 (adhesive layers aye and 24b) such as tape No. 1512 available from the EM Company of S-t.
Paul, Minnesota. Sweat collector 22 and plastic tape 24 also contain a central inlet opening aligned with the opening in layer 20 and with the center of circle 12. A piece of absorbent paper or the like is inserted into the inlet opening of the sweat collector as a wick-like plug 28 through Welch sweat enters the device to gain access to indicating layer 10. Sweat collector 22 also preferably includes a plurality of radiating indentations (best seen in jig. I 26 which function to channel sweat to the inlet opening. These indentations may be formed by pressing or scribing the contact sun-face of the collector, i.e., the surface which is intended to contact the skin.
Inner circle 12 of indicating layer 10 is impregnated with a reactant so as to screen out all chloride in the sweat absorbed by the indicating layer below a predetermined concentration such as the alone-mentioned 45 my. Outer ring 14 of indicating layer 10 is impregnated with a reactant so as Jo reflect the presence of chloride in excess of the screened con-cent ration level by undergoing a color change to visually indicate the presence of the excess chloride.
Tab 16 is also impregnated with a suitable composition to provide a visual indication that the indicating layer is saturated with the intended volume of sweat such as the aforementioned 50 I amount. The fill tab indicator undergoes a color change only if -the device absorbs the required volume of sweat. This serves as an indication -that insufficient sweat has been generated and absorbed and likewise as an indicator that a sufficient amount of sweat has been generated and absorbed to complete the test.
he preferred absorbent medium for bodies 12, 14 and 16 is filter paper or chromatography paper. No. 20 chromatography paper from Whitman, Inc., Paper Division, Clifton, New Jersey, is most preferred.
Circles of desired size for inner circle 12 are preferably cut from sheets of such paper which have been impregnated with a controlled amount of silver phosphate. Preferably, the sheet is first impregnated with silver nitrate and dried. It is then impregnated l !
with sodium phosphate to cause -the formation of a silver phosphate precipitate in situ. These operations must be performed in subdued light. The silver phosphate thus formed has been found to be relatively immobile in the paper thus remaining fixed when sweat migrates through the circle. It gives the paper a yellow appearance.
Indicating rings 14 are cut to desired size from sheets of No. 20 chromatography paper which have been impregnated with silver cremate. The impregnation process is analogous to that described above in that the paper is first wet-ted with a silver nitrate soul-lion, dried and then wetted with a potassium chromates solution to form silver chromates in situ.
Fill indicator tabs 16 are cut from the same sheets of paper which have been impregnated with silver nitrate in the same way.
Circle 12 (silver phosphate paper) is fitted inside brown ring 14 (silver chromates paper) and pressed together at 2600 lbs/sq. inch. This assembly is then placed on the adhesive side aye of non-absorbent tape 18. Fill indicator tab 16 is placid on adhesive side aye of tape 18 so that one edge touches the outer edge of ring 14. A hole or inlet opening, preferably approximately .04 inches, is punched in a second piece of tape i.e., layer 20 and this tape is placed over the paper bodies which are then sealed between the two tape layers with gentle pressing. The hole therein should be aligned so that it is in the center of circle 12.
I Channels 26 are formed in a radiating pattern in collector 22 which is preferably a piece of high den-sty polyethylene non-woven fiber sheet. A hole, approximately .04 inches preferably, is punched in the center of sheet 22 and the sheet is attached to tape layer 20 with -the holes aligned by means of the non-I
I
absorbent, double-backed adhesive tape 24 (which also has a .04 inch hole in its center. Wick-like plug 28 is formed from a plain piece of No. 20 chromatography paper which is punched to fit into the hole in the polyethylene sheet 22 and inserted therein as indicated in Figure 3.
The operation of the device is as follows.
Sweating is induced in a subject by any of a variety of methods For example, sweat inducing drugs may be infused by iontophoresis techniques. After such a pro-seedier, the skin area is cleaned with distilled water and dried. The test device is then taped over this cleaned area with the collector side of the device next to the skin. As sweat is generated the collector chant nets direct it towards the inlet opening where it enters the device by passing through the plug. The sweat enters the device at the center of inner circle 12. It radially diffuses through this first reaction area. Chloride in the diffusing sweat reacts with the impregnated silver phosphate in circle 12 as shown in reaction (1).
(1) owe clue -I Agape axle + H2PO~ + 20H
As already indicated, sufficient silver phosphate has been impregnated in circle 12 so as to complex all I chloride in the absorbed sweat sample below a predator-mined concentration such as the aforementioned 45 my vet us.
The sweat sample continues to radially diffuse out-warmly and it enters ring 14. Any excess chloride i.e., chloride not reacted with the silver phosphate in circle 12, then reacts with the impregnated silverchromate in ring 14 as shown in reaction (2).
I
.
I. DESCRIPTION
Background of the Invention _ The test device of the invention is designed to perform a quantitative test on a given volume of a fluid to provide a visual indication when a certain substance is present in the fluid in an amount in excess of a predetermined amount.
In its preferred embodiment, the test device of -the invention is specifically directed -to a flat absorbent test patch device used in the screening of persons for cystic fibrosis. Consequently, the invention although of general applicability is described herein with spew cilia reference to wits use in screen testing for cystic fibrosis.
A simple screening -test is particularly needed for cystic fibrosis because of its high incidence in children. About 1 in 1000 to 1 in 1~00 infants are born with cystic fibrosis. Those having cystic fiber-skis exhibit high mortality. As recently as 1963 one-third of the deaths from cystic fibrosis occurred in the first year of life; two-thirds in the firs-t five years. The prognosis has recently improved due to early therapy and mortality has decreased to less than five percent in -the first year of life. A group half-life of over 20 years can be reasonably expected if treatment is early.
An abnormality which is used to i~lenti~y persons having mystic fibrosis is the unusually high chloride concentration in -their sweat. A sweat chloride con-cent ration significantly greater than normal is constantly present in all persons suffering from this disease.
D it Brief Summary of the Invention The device includes a first reaction area, prefer-ably in the form of a circular, preferably flat, absorb bent booty contacted by a surrounding, preferably flat, body of absorbent material which provides a second reaction area Preferably the surrounding body is circular or ring-shaped, although it may be any other shape. The outer or perimeter edge of the circular first reaction area contacts the entire inner edge of the ring-shaped second reaction area. A third reaction area, preferably in the shape of a small absorbent -tab or even a complete, surrounding, outer body which may be ring-shapecl also or any other shape, contacts the outer diameter of the second reaction area body. The purpose of the tab or its equivalent is to signify when the device is saturated with a given volume of the fluid being absorbed for test.
The absorbent bodies are enclosed in a preferably flat, fluid tight envelope which is transparent on a-t least one side at least in the outer reaction area and frill indication area. The opposite side contains an inlet opening aligned with the center of -the first reaction area for the introduction of the test fluid, such as sweat, thereto. This side also preferably carries a fluid collector which directs fluid to the inlet opening.
By selecting absorbent bodies of known absorbency and sizing them properly, the device is constructed and arranged to absorb a predetermined fixed volume of test fluid, such as sweat, to be evaluated for its content owe a substance, such as chloride, in excess of a prude-termined amount.
The inner circle or first reaction area is impregnated with a predetermined amount of a reactant which is provided in an amount sufficient to react with '.
. ' : ,, all of the substance contained in the absorbed -test fluid below a predetermined concentration value. The second reaction area or outer ring is also impregnated with a reactant which reacts with the substance in the test fluid also. However, since the fluid is intro-duped at the center of the first reaction area an must migrate radially there through before reaching the con-centric ring or second reaction area, the composition in the first reaction area reacts with any substance in the fluid below the predetermined value first. Any substance in the fluid in excess of the predetermined value is free to react with the reactant in the second reaction area only upon migration of the fluid and substance thereto. The reactant in the second reaction area is selected to provide color change upon exposure to or reaction with the excess substance thus visually indicating the fact that substance in excess of the predetermined amount is present in the test fluid.
The tab or its equivalent contains a reactant son-sitive to the fluid or a component thereof which undergoes a visual change in appearance upon its being reached by the migraine fluid to indicate -that -the first and second reaction areas are saturated with the fluid and a fixed volume thereof has been collected.
Brief Description of the Drawings Fig. 1 and 2 are -top and bottom views, respect lively, of a device according to the invention.
Fig. 3 is a schematic cross section taken through -the center of the device shown in Fig. 1.
Detailed Description of the Preferred Embodiment . .
The preferred embodiment of the device is intended for use in screen testing of subjects for cystic fiber-skis. It is constructed and arranged to absorb a 50Jdl ' test sample of sweat and to indicate the presence of chloride in the sweat in excess of a concentration of 45 my by providing a suitable, visually apparent, color change in the outer ring of the device. It may he modified to absorb differing amounts of sweat or other test fluids and to provide visual indication of various excess amounts of chloride or other fluid-contained substances. It is particularly useful for aqueous fluids having a dissolved salt to be determined.
Referring now to -the Figures, the device is comprised of an indicating layer generally indicated at 10 in Fig. 3. Indicating layer 10 includes inner circle 12, concentric ring 14 and tax 16 (seen in Fig.
1). Circle 12, ring 14 and tab 16 are of fluid absorb bent material such as filter paper or chromatography paper and are preferably substantially flat. These bodies are assembled such that circle 12 lies inside ring 14 with the outer edge of circle 12 contacting the inner diameter of ring 14. Tab 16 contacts the outer diameter or edge of ring 14 as shown. Upon assembly of the three absorbent bodies into their operating rota-tionship they are preferably subjected to pressure erg., 2600 lbs/sq inch to press them together. Tab 16 may be modified into various other shapes. For example, it I may be a third concentric ring, ring segment or other shaped surrounding body. Generally, it may be any shape or form so long as it contacts the outer edge of ring 14 and provides a visually apparent color change when contacted by the fluid being absorbed or a keenest-tent thereof.
The arrangement shown provides an indicating layer capable of absorbing a given volume of sweat depending on the size and weight of the absorbent paper selected and the overall size of the circular and ring-shaped bodies.
I
The various reaction areas may also be portio7ls of a single body of absorbent material impregnated with a suitable pattern of reactant materials.
Indicating layer 10 is enclosed in a non-absorbent fluid-tight envelope comprised of an overlaying transparent layer 18 and an underlying hacking layer 20. Layer 18 is transparent at least in a visually apparent portion of the second reaction area and of the fill indicator area. Layer 20 may be transparent also but not necessarily. suitable and most preferred material for layers 18 and 20 is transparent adhesive plastic tape such as polyester tape obtained from Bel-Art Products, Picnic, New Jersey which markets a tape identified as "Lab Label Protection Tape". This tape has been found to be somewhat resistant to cold flow, nonabsorbent and suitably transparent for use in forming the envelope in which indicating layer 10 is sealed between opposing adhesive surfaces of the tape aye and aye, respectively. Ire 20 is then provided wit a small central opening 21 aligned with the center of circle 12 to provide an inlet opening for sweat to gain access to indicating layer 10.
A sweat collector 22, preferably comprised of high density polyethylene non-woven sheet such a TYVEK~, obtained from the Paper Manufacturing Company of Philadelphia, is then attached to layer 20. Preferably this is accomplished by means of a double backed ache-size plastic tape 24 (adhesive layers aye and 24b) such as tape No. 1512 available from the EM Company of S-t.
Paul, Minnesota. Sweat collector 22 and plastic tape 24 also contain a central inlet opening aligned with the opening in layer 20 and with the center of circle 12. A piece of absorbent paper or the like is inserted into the inlet opening of the sweat collector as a wick-like plug 28 through Welch sweat enters the device to gain access to indicating layer 10. Sweat collector 22 also preferably includes a plurality of radiating indentations (best seen in jig. I 26 which function to channel sweat to the inlet opening. These indentations may be formed by pressing or scribing the contact sun-face of the collector, i.e., the surface which is intended to contact the skin.
Inner circle 12 of indicating layer 10 is impregnated with a reactant so as to screen out all chloride in the sweat absorbed by the indicating layer below a predetermined concentration such as the alone-mentioned 45 my. Outer ring 14 of indicating layer 10 is impregnated with a reactant so as Jo reflect the presence of chloride in excess of the screened con-cent ration level by undergoing a color change to visually indicate the presence of the excess chloride.
Tab 16 is also impregnated with a suitable composition to provide a visual indication that the indicating layer is saturated with the intended volume of sweat such as the aforementioned 50 I amount. The fill tab indicator undergoes a color change only if -the device absorbs the required volume of sweat. This serves as an indication -that insufficient sweat has been generated and absorbed and likewise as an indicator that a sufficient amount of sweat has been generated and absorbed to complete the test.
he preferred absorbent medium for bodies 12, 14 and 16 is filter paper or chromatography paper. No. 20 chromatography paper from Whitman, Inc., Paper Division, Clifton, New Jersey, is most preferred.
Circles of desired size for inner circle 12 are preferably cut from sheets of such paper which have been impregnated with a controlled amount of silver phosphate. Preferably, the sheet is first impregnated with silver nitrate and dried. It is then impregnated l !
with sodium phosphate to cause -the formation of a silver phosphate precipitate in situ. These operations must be performed in subdued light. The silver phosphate thus formed has been found to be relatively immobile in the paper thus remaining fixed when sweat migrates through the circle. It gives the paper a yellow appearance.
Indicating rings 14 are cut to desired size from sheets of No. 20 chromatography paper which have been impregnated with silver cremate. The impregnation process is analogous to that described above in that the paper is first wet-ted with a silver nitrate soul-lion, dried and then wetted with a potassium chromates solution to form silver chromates in situ.
Fill indicator tabs 16 are cut from the same sheets of paper which have been impregnated with silver nitrate in the same way.
Circle 12 (silver phosphate paper) is fitted inside brown ring 14 (silver chromates paper) and pressed together at 2600 lbs/sq. inch. This assembly is then placed on the adhesive side aye of non-absorbent tape 18. Fill indicator tab 16 is placid on adhesive side aye of tape 18 so that one edge touches the outer edge of ring 14. A hole or inlet opening, preferably approximately .04 inches, is punched in a second piece of tape i.e., layer 20 and this tape is placed over the paper bodies which are then sealed between the two tape layers with gentle pressing. The hole therein should be aligned so that it is in the center of circle 12.
I Channels 26 are formed in a radiating pattern in collector 22 which is preferably a piece of high den-sty polyethylene non-woven fiber sheet. A hole, approximately .04 inches preferably, is punched in the center of sheet 22 and the sheet is attached to tape layer 20 with -the holes aligned by means of the non-I
I
absorbent, double-backed adhesive tape 24 (which also has a .04 inch hole in its center. Wick-like plug 28 is formed from a plain piece of No. 20 chromatography paper which is punched to fit into the hole in the polyethylene sheet 22 and inserted therein as indicated in Figure 3.
The operation of the device is as follows.
Sweating is induced in a subject by any of a variety of methods For example, sweat inducing drugs may be infused by iontophoresis techniques. After such a pro-seedier, the skin area is cleaned with distilled water and dried. The test device is then taped over this cleaned area with the collector side of the device next to the skin. As sweat is generated the collector chant nets direct it towards the inlet opening where it enters the device by passing through the plug. The sweat enters the device at the center of inner circle 12. It radially diffuses through this first reaction area. Chloride in the diffusing sweat reacts with the impregnated silver phosphate in circle 12 as shown in reaction (1).
(1) owe clue -I Agape axle + H2PO~ + 20H
As already indicated, sufficient silver phosphate has been impregnated in circle 12 so as to complex all I chloride in the absorbed sweat sample below a predator-mined concentration such as the aforementioned 45 my vet us.
The sweat sample continues to radially diffuse out-warmly and it enters ring 14. Any excess chloride i.e., chloride not reacted with the silver phosphate in circle 12, then reacts with the impregnated silverchromate in ring 14 as shown in reaction (2).
I
.
(2) clue Ag2CrO4 _ axle + Crow (Brown) (White Consequently, any chloride above the predetermined concentration is indicated visually by -the appearance of a white area in ring 14.
Ring 14 preferably contains silver chromates formed in situ plus a slight excess amount of potassium cry-mate as shown in -the Example below. As the sweat sample continues to diffuse outwardly in ring 14 it carries some of the soluble potassium chromates with it.
When fill tab 16 is contacted by the sweat sample now containing the soluble chromates the following reaction takes place (3).
Ring 14 preferably contains silver chromates formed in situ plus a slight excess amount of potassium cry-mate as shown in -the Example below. As the sweat sample continues to diffuse outwardly in ring 14 it carries some of the soluble potassium chromates with it.
When fill tab 16 is contacted by the sweat sample now containing the soluble chromates the following reaction takes place (3).
(3) agony + Crow Ag2CrO4 + OWE
(Brown) The tab turning brown indicates that sufficient sweat has been collected to saturate indicating layer 10 and that the test is complete.
EXAMPLE
A test patch capable of holding a 50 I sweat sample and producing a color change in the indicating layer at 45 my level of chloride concentration should have the following characteristics:
(1) inner circle 12 - 1/2 inch diameter I impregnated with 1.7 X 10 6 moles of silver phosphate 2) indicating ring 14 1 inch Ozone half inch ID, impregnated with about 2.2 X 10-6 moles of silver chromates and 4 X 10-7 moles of potassium chromates The excess chromates is used to produce the color change in fill tab 16 when the device is completely filled with fluid.
(3) Fill tab 16 - 1/8 inch by 1/4 inch impregnated with 1.2 X 10 7 moles of silver nitrate.
(Paper used throughout - Whitman No. 20 chromatography grade, thickness 0.165) The amount of silver in circle 12 is slightly less than the amount required to complex all of the chloride in 50 I of a 45 my sample. The reason for this is what the last of the sweat sample to enter the test patch at inner circle 12 does not diffuse out to ring 14 and is therefore not involved in the reaction.
For cystic fibrosis application silver dichromate may also be used as the screening composition in ring 14. Cuprous chloride and chronic chloride may be used as color indicators for fill -tabs 16. Other reactants are also considered to be within the scope of this invention and will be determined for any specific test fluid.
The following procedure has been found to be useful in impregnating the paper with a reproducible and evenly distributed amount of reactant.
A piece of dry bulk paper of known weight and size is saturated with water, placed between two sheets of 5 mix plastic sheet (erg., Teflon) and passed through the rollers of a pasta maker to remove excess water. The bulk paper is immediately reweighed and from the dip-furriness in weight (wet-dry) the impregnation volume can be calculated. Using a #l setting on the pasta maker, the procedure has been found to yield an average impregnation amount of 39J~l/in2 inn. It was noted that the speed one uses in rotating the rollers I has an effect on impregnation amounts. If the speed is slow more liquid is squeezed out of the paper. If it is fast, less liquid is squeezed out and the resulting impregnation volume is higher. A uniform rotational speed should be selected and used throughout.
trade fv1Q ok, I
Once the impregnation volume of the paper is deter-mined, the concentration of -the various impregnation solutions can be determined for any given situation.
Two important volumes must be known in order to S construct this test patch. The first is the impregna-lion volume of the paper This is a volume of impregnation solutions per square inch that the paper will hold. It must be experimentally determined using whatever impregnation procedure is developed, such as the method using pasta rollers described above. For Whitman #20 paper -the impregnation volume was found to be 39 1 I per square inch under the condition described here. Once this volume is known the con-cent ration of chemicals needed to impregnate the bulk paper can easily be determined. The second volume of interest is the volume of test fluid the test patch will absorb during the screening test. It should be noted that this volume may be quite different from the impregnation volume. the absorption volume must be determined for the patch as constructed, i.e., with the specific kind of paper and the pressing conditions used during construction. For the test patch of the pro--furred embodiment the absorption volume was found to be 64 + 3 I per square inch. It must be remembered that a volume of solution equal to that absorbed by inner circle 12 will never migrate to outer ring 14 during the test. Therefore, the calculation of the amount of silver phosphate needed to be impregnated into inner circle 12 depends only upon the size of outer ring 14.
Thus, the volume of impregnation chemicals are cowlick-fated from the absorption volume and the size of theater ring. It turns out that 1.7 X 10 6 moles of chloride must be screened out in inner 1/2 inch circle 12 in the preferred embodiment described in the above Example. The impregnation volume for a 1/2 inch diameter circle is equal to 39Jul/sq. inch X 0.20 so.
inch (circle area) or 7.8J~l. This volume of solution must contain the required amount of silver for screening out the chloride or 1.7 X 10-6 moles. The concentration of the ~N03 impregnating solution is, therefore, 1.7 X 10-6 moles divided by 7.8~1 or 0.22 M. The Agony is reacted with Nope to provide the fixed silver phosphate reactant. A 0.21 M
Agony solution requires a 0.07 M Nope solution for stoichiometric formation of silver phosphate.
The preferred embodiment of the invention uses a test patch including an inner circle of 1/2 inch diameter and an outer ring about it bringing the total area to one inch. The inner circle must be impregnated with a specific amount of a certain concentration of Agony This is necessary so that the Agape can be formed in the inner circle in a predetermined amount which will screen out 45 my of chloride or whatever predetermined amount is desired) in a given volume of sweat, such as 50J~l.
Outer ring 14 is used only as an indicating layer for excess chloride and the specific concentration of Ag2CrO4 is not critical. However, it has been deter-mined that lower concentrations of Ag2CrO4 produce a more desirable result due to the fact that any excess chloride will produce a more significant visual change Specifically, if one uses a high concentration of Ag2CrO4, when the excess chloride enters outer ring 14 there is so much silver ion in close proximity to inner circle 12 that all Axle formation occurs in the area of the outer ring which is in very close proximity to thinner circle. By lowering the silver chromates con-cent ration somewhat in the outer ring, the chloride can migrate further into it to provide an enlarged area of reaction and hence an enlarged visual indication of Jo excess chloride. For example, one may preferably use 0.10 M Agony and 0.07 M Cry solutions to impregnate the outer ring for the most preferred embodiment of the invention.
For other applications, varying reactants may be used in the indicating layer. Various materials for the indicating layer per so and the sealing envelope as well as the collector and plug may also be used. The embodiments described herein has been by way of illustration only.
WHAT IS CLAIMED IS:
(Brown) The tab turning brown indicates that sufficient sweat has been collected to saturate indicating layer 10 and that the test is complete.
EXAMPLE
A test patch capable of holding a 50 I sweat sample and producing a color change in the indicating layer at 45 my level of chloride concentration should have the following characteristics:
(1) inner circle 12 - 1/2 inch diameter I impregnated with 1.7 X 10 6 moles of silver phosphate 2) indicating ring 14 1 inch Ozone half inch ID, impregnated with about 2.2 X 10-6 moles of silver chromates and 4 X 10-7 moles of potassium chromates The excess chromates is used to produce the color change in fill tab 16 when the device is completely filled with fluid.
(3) Fill tab 16 - 1/8 inch by 1/4 inch impregnated with 1.2 X 10 7 moles of silver nitrate.
(Paper used throughout - Whitman No. 20 chromatography grade, thickness 0.165) The amount of silver in circle 12 is slightly less than the amount required to complex all of the chloride in 50 I of a 45 my sample. The reason for this is what the last of the sweat sample to enter the test patch at inner circle 12 does not diffuse out to ring 14 and is therefore not involved in the reaction.
For cystic fibrosis application silver dichromate may also be used as the screening composition in ring 14. Cuprous chloride and chronic chloride may be used as color indicators for fill -tabs 16. Other reactants are also considered to be within the scope of this invention and will be determined for any specific test fluid.
The following procedure has been found to be useful in impregnating the paper with a reproducible and evenly distributed amount of reactant.
A piece of dry bulk paper of known weight and size is saturated with water, placed between two sheets of 5 mix plastic sheet (erg., Teflon) and passed through the rollers of a pasta maker to remove excess water. The bulk paper is immediately reweighed and from the dip-furriness in weight (wet-dry) the impregnation volume can be calculated. Using a #l setting on the pasta maker, the procedure has been found to yield an average impregnation amount of 39J~l/in2 inn. It was noted that the speed one uses in rotating the rollers I has an effect on impregnation amounts. If the speed is slow more liquid is squeezed out of the paper. If it is fast, less liquid is squeezed out and the resulting impregnation volume is higher. A uniform rotational speed should be selected and used throughout.
trade fv1Q ok, I
Once the impregnation volume of the paper is deter-mined, the concentration of -the various impregnation solutions can be determined for any given situation.
Two important volumes must be known in order to S construct this test patch. The first is the impregna-lion volume of the paper This is a volume of impregnation solutions per square inch that the paper will hold. It must be experimentally determined using whatever impregnation procedure is developed, such as the method using pasta rollers described above. For Whitman #20 paper -the impregnation volume was found to be 39 1 I per square inch under the condition described here. Once this volume is known the con-cent ration of chemicals needed to impregnate the bulk paper can easily be determined. The second volume of interest is the volume of test fluid the test patch will absorb during the screening test. It should be noted that this volume may be quite different from the impregnation volume. the absorption volume must be determined for the patch as constructed, i.e., with the specific kind of paper and the pressing conditions used during construction. For the test patch of the pro--furred embodiment the absorption volume was found to be 64 + 3 I per square inch. It must be remembered that a volume of solution equal to that absorbed by inner circle 12 will never migrate to outer ring 14 during the test. Therefore, the calculation of the amount of silver phosphate needed to be impregnated into inner circle 12 depends only upon the size of outer ring 14.
Thus, the volume of impregnation chemicals are cowlick-fated from the absorption volume and the size of theater ring. It turns out that 1.7 X 10 6 moles of chloride must be screened out in inner 1/2 inch circle 12 in the preferred embodiment described in the above Example. The impregnation volume for a 1/2 inch diameter circle is equal to 39Jul/sq. inch X 0.20 so.
inch (circle area) or 7.8J~l. This volume of solution must contain the required amount of silver for screening out the chloride or 1.7 X 10-6 moles. The concentration of the ~N03 impregnating solution is, therefore, 1.7 X 10-6 moles divided by 7.8~1 or 0.22 M. The Agony is reacted with Nope to provide the fixed silver phosphate reactant. A 0.21 M
Agony solution requires a 0.07 M Nope solution for stoichiometric formation of silver phosphate.
The preferred embodiment of the invention uses a test patch including an inner circle of 1/2 inch diameter and an outer ring about it bringing the total area to one inch. The inner circle must be impregnated with a specific amount of a certain concentration of Agony This is necessary so that the Agape can be formed in the inner circle in a predetermined amount which will screen out 45 my of chloride or whatever predetermined amount is desired) in a given volume of sweat, such as 50J~l.
Outer ring 14 is used only as an indicating layer for excess chloride and the specific concentration of Ag2CrO4 is not critical. However, it has been deter-mined that lower concentrations of Ag2CrO4 produce a more desirable result due to the fact that any excess chloride will produce a more significant visual change Specifically, if one uses a high concentration of Ag2CrO4, when the excess chloride enters outer ring 14 there is so much silver ion in close proximity to inner circle 12 that all Axle formation occurs in the area of the outer ring which is in very close proximity to thinner circle. By lowering the silver chromates con-cent ration somewhat in the outer ring, the chloride can migrate further into it to provide an enlarged area of reaction and hence an enlarged visual indication of Jo excess chloride. For example, one may preferably use 0.10 M Agony and 0.07 M Cry solutions to impregnate the outer ring for the most preferred embodiment of the invention.
For other applications, varying reactants may be used in the indicating layer. Various materials for the indicating layer per so and the sealing envelope as well as the collector and plug may also be used. The embodiments described herein has been by way of illustration only.
WHAT IS CLAIMED IS:
Claims (25)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A test device which provides a visual indica-tion of the content of a substance in a fluid in excess of a predetermined amount, comprising: absorbent means of a predetermined absorbency for absorbing a predeter-mined volume of fluid, the absorbent means defining first and second reaction areas; the first reaction area being circular in shape, of a predetermined diameter and including a centrally located opening defining an inlet to the first reaction area for the introduction of the substance-containing fluid thereto;
the second reaction area being arranged in intercon-necting relationship with the first reaction area about the perimeter of the first reaction area whereby fluid introduced into the center of the first area migrates radially outward through the first area and into the second area; the first reaction area including a com-position of predetermined amount which reacts with an initial amount of the substance in the fluid, up to the predetermined amount, so as to preclude any substantial effect of such initial amount of the substance in the second reaction area; the second reaction area including a composition which undergoes a visual change in appearance upon contact with any substance remaining in the fluid after migration of the fluid through the first reaction area to produce a visual change in appearance of at least a portion of the second reaction area upon migration of substance-containing fluid into the second reaction area thereby indicating the pre-sence of the substance in the fluid in excess of the predetermined amount.
the second reaction area being arranged in intercon-necting relationship with the first reaction area about the perimeter of the first reaction area whereby fluid introduced into the center of the first area migrates radially outward through the first area and into the second area; the first reaction area including a com-position of predetermined amount which reacts with an initial amount of the substance in the fluid, up to the predetermined amount, so as to preclude any substantial effect of such initial amount of the substance in the second reaction area; the second reaction area including a composition which undergoes a visual change in appearance upon contact with any substance remaining in the fluid after migration of the fluid through the first reaction area to produce a visual change in appearance of at least a portion of the second reaction area upon migration of substance-containing fluid into the second reaction area thereby indicating the pre-sence of the substance in the fluid in excess of the predetermined amount.
2. The indicator device of claim 1 wherein the second reaction area defines an inner edge surrounding and contacting the perimeter of the first reaction area and an outer edge and there is included a third absor-bent reaction area in contact with the outer edge of the second reaction area.
3. The indicator device of claim 2 wherein the second reaction area is ring-shaped.
4. The indicator device of claim 2 wherein the third absorbent reaction area is tab-shaped.
5. The device of claim 1 wherein the composition in the first reaction area comprises silver phosphate and the composition in the second reaction area compri-ses silver chromate.
6. The device of claim 1 wherein the composition in the first reaction area comprises silver phosphate and the composition in the second reaction area compri-ses silver dichromate.
7. The device of claim 5 wherein the second reac-tion area defines an inner edge contacting the peri-meter of the first reaction area and an outer edge and there is included a third absorbent reaction area in contact with the outer edge of the second reaction area, the third reaction area including a composition comprised of silver nitrate.
8. A test device of substantially flat construc-tion for application to the body and the collection of a test sample of sweat, comprising: an upper layer of absorbent means of predetermined absorbency for absorbing a predetermined volume of sweat, the absor-bent means defining first and second reaction areas, the first reaction area being circular in shape, of a predetermined diameter and including a centrally located opening defining an inlet to the first reaction area for the introduction of sweat thereto; the second reaction area being arranged in interconnecting rela-tionship with the first reaction area about the peri-meter thereof whereby sweat introduced at the inlet migrates radially outwardly through the first area and into the second area; the first reaction area including a predetermined amount of a composition for reaction with an initial predetermined amount of chloride in the sweat; the second reaction area including a composition which undergoes a visual change in appearance upon contact with any chloride remaining in the sweat after its migration through the first reaction area thereby indicating the presence of any chloride remaining in the sweat in excess of the prede-termined amount, and a lower substantially non-absorbent, collector layer for contacting the skin and collecting the sweat sample, the lower layer including on its skin contacting surface a central inlet opening aligned with the inlet opening of the first reaction area and a plurality of radially extending channels leading to the opening for collecting sweat and directing it into the device.
9. The indicator device of claim 8 wherein the second reaction area defines an inner edge contacting the perimeter of the first reaction area and an outer edge, and there is included a third absorbent reaction area in contact with the outer edge of the second reac-tion area.
10. The indicator device of claim 9 wherein the second reaction area is ring-shaped.
11. The indicator device of claim 9 wherein the third absorbent reaction area is tab-shaped.
12. The device of claim 8 wherein the composition in the first reaction area comprises silver phosphate and the composition in the second reaction area compri-ses silver chromate.
13. The device of claim 12 wherein silver dichro-mate replaces the silver chromate.
14. The device of claim 12 wherein the second reaction area defines an inner edge contacting the perimeter of the first reaction area and an outer edge, and there is included a third absorbent reaction area in contact with the outer edge of the second reaction area, the third reaction area including a composition comprised of silver nitrate.
15. The device of claim 12 wherein the silver phosphate is included in an amount to react with about 45 mM of chloride in the sweat.
16. The device according to claim 8 wherein the absorbent means defining the first and second reaction areas is comprised of a circular-shaped body defining the first reaction area and a ring-shaped body defining the second reaction area, the circular-shaped body being positioned within the enclosed central area of the ring-shaped body, the two bodies being of such size relative to each other so as to be substantially con-tiguous along the outer edge of the circular-shaped body and the inner edge of the ring-shaped body.
17. The device according to claim 16 wherein the composition in the circular-shaped body comprises silver phosphate and the composition in the ring-shaped body comprises silver chromate.
18. The device of claim 17 wherein silver dichro-mate replaces the silver chromate.
19. The device according to claim 16 wherein the circular-shaped body and the ring-shaped body are of an absorbency and size selected to provide a holding capa-city for a predetermined volume of the fluid.
20. The device according to claim 16 including a tab of absorbent material contacting the ring-shaped body at its outer periphery.
21. The device according to claim 20 wherein the composition in the tab is silver nitrate.
22. The device of claim 8 including:
a transparent cover layer means on top of the absorbent means and a backing layer under the absorbent means, the two layers being sealed together to enclose the absorbent means therebetween, the backing layer including an opening aligned with the center of the first reaction area of the absorbent means, and the collector layer is attached to the backing layer with the inlet opening thereof aligned with the opening in the backing layer.
a transparent cover layer means on top of the absorbent means and a backing layer under the absorbent means, the two layers being sealed together to enclose the absorbent means therebetween, the backing layer including an opening aligned with the center of the first reaction area of the absorbent means, and the collector layer is attached to the backing layer with the inlet opening thereof aligned with the opening in the backing layer.
23. The device of claim 8 wherein the absorbency of the porous medium is selected to absorb about 45-55 µ1 of sweat.
24. The method of forming silver phosphate in situ in an absorbent medium whereby the silver phosphate is substantially fixed in the medium and resistant to displacement by a migrating fluid, comprising the steps:
wetting the absorbent medium with silver nitrate solution;
drying the medium, and reacting the silver nitrate in the medium with sodium phosphate solution.
wetting the absorbent medium with silver nitrate solution;
drying the medium, and reacting the silver nitrate in the medium with sodium phosphate solution.
25. The method of forming silver chromate or silver dichromate in situ in an absorbent medium comprising the steps:
wetting the absorbent medium with silver nitrate solution;
drying the medium, and reacting the silver nitrate in the medium with a quantity of potassium chromate or dichromate solution slightly in excess of the silver nitrate.
wetting the absorbent medium with silver nitrate solution;
drying the medium, and reacting the silver nitrate in the medium with a quantity of potassium chromate or dichromate solution slightly in excess of the silver nitrate.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US338,274 | 1982-01-11 | ||
| US06/338,274 US4444193A (en) | 1982-01-11 | 1982-01-11 | Fluid absorbent quantitative test device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1217698A true CA1217698A (en) | 1987-02-10 |
Family
ID=23324133
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000419172A Expired CA1217698A (en) | 1982-01-11 | 1983-01-10 | Fluid absorbent quantitative test device |
Country Status (4)
| Country | Link |
|---|---|
| US (1) | US4444193A (en) |
| EP (1) | EP0083941B1 (en) |
| CA (1) | CA1217698A (en) |
| DE (1) | DE3368325D1 (en) |
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| US4209020A (en) * | 1978-09-19 | 1980-06-24 | Nielsen R Frederick | Electrode assembly |
| US4230105A (en) * | 1978-11-13 | 1980-10-28 | Merck & Co., Inc. | Transdermal delivery of drugs |
| US4250878A (en) * | 1978-11-22 | 1981-02-17 | Motion Control, Inc. | Non-invasive chemical species delivery apparatus and method |
| US4329999A (en) * | 1980-03-03 | 1982-05-18 | Michael Phillips | Patient attached patch and method of making |
-
1982
- 1982-01-11 US US06/338,274 patent/US4444193A/en not_active Expired - Lifetime
-
1983
- 1983-01-10 DE DE8383100142T patent/DE3368325D1/en not_active Expired
- 1983-01-10 CA CA000419172A patent/CA1217698A/en not_active Expired
- 1983-01-10 EP EP83100142A patent/EP0083941B1/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2013057470A1 (en) | 2011-10-19 | 2013-04-25 | The Secretary Of State For Defence | Heat acclimatisation monitoring |
Also Published As
| Publication number | Publication date |
|---|---|
| EP0083941A1 (en) | 1983-07-20 |
| DE3368325D1 (en) | 1987-01-22 |
| EP0083941B1 (en) | 1986-12-10 |
| US4444193A (en) | 1984-04-24 |
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| Date | Code | Title | Description |
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| MKEX | Expiry |