# Patent

## Title
Changed condition indicator

## Abstract

A system and method for indication of temperature exposures beyond a set of predetermined limits employs the salts of weak acid-strong base or of a strong acid-weak base compound as reactants. A device includes a housing and capsule. A first reactant and a liquid are included within the capsule. The liquid is chosen such that it expands upon freezing. The capsule is sized such that when the liquid freezes and expands, the capsule fractures. A second reactant is provided within the housing. The location of the second reactant and the method of attaching (if any) the second reactant to the housing may take various forms. When the liquid within the capsule freezes, it expands and fractures the capsule. Upon thawing, the reactant within the capsule escapes and mixes with the reactant located outside the capsule. A second embodiment is a time-temperature indicator. A flexible housing is used, allowing the user to manually deform the housing to fracture a capsule enclosed therein. The reactants combine to produce a color. The color is chosen to be a different color than the housing, allowing a person viewing the indicator device to quickly and easily determine the status of the object being monitored. The threshold temperature at which the device will indicate a changed condition may be varied. Exemplary temperatures include below the freezing temperature, at the freezing temperature, and above the freezing temperature. The capsule composition may be varied such that it melts at a predetermined temperature. Thus, the device may also be used to indicate whether a high temperature has been met or exceeded.

## Background
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a Continuation-in-Part of Ser. No. 10/782,801 filed Feb. 23, 2004 U.S. Pat. No. 7,011,037 entitled Changed Condition Indicator issued Mar. 14, 2006, which is a Continuation-in-Part of Ser. No. 09/925,538 filed Aug. 10, 2001 U.S. Pat. No. 6,694,913 entitled Changed Condition Indicator which issued on Feb. 24, 2004.


FIELD OF THE INVENTION
This invention relates to an indicating apparatus and more particularly, to devices for indicating a change in temperature.
BACKGROUND OF THE INVENTION
In the preparation and storage of foodstuffs, both raw and cooked, it is desirable to have some manner of indicating whether frozen items have previously been thawed. This is true in both home and commercial (such as a grocery store, supermarket, or restaurant) settings. Such information is useful from health, safety, and nutritional standpoints.
In the healthcare industry, it is well known that some vaccines, blood, various medications, etc. are temperature-sensitive. Because such materials may not function properly if frozen and then thawed, it is not only desirable but also essential to know whether these materials have been previously frozen. Similarly, it would be very beneficial to know whether material, which is stored frozen, is allowed to thaw and subsequently is refrozen. Furthermore, it would be very beneficial to know whether material has been cooled below and then heated above a threshold temperature other than the freezing temperature (i.e., above or below the freezing temperature).
It is also desirable in the foodstuff, medical, and other industries to know whether material has been raised above a certain temperature. For example, some vaccines are known to not function properly if stored above a certain temperature. Thus, it would be beneficial to know whether stored material has previously been heated above a predetermined temperature.
Maximum-minimum thermometers may be used to indicate the range of temperatures to which an item has been exposed. However, the use of such apparatus with every item in a frozen food department of a grocery store or supermarket, or with every container of vaccine, blood, drug, or other heat fragile item, is both impracticable and prohibitively costly.
Freeze-thaw indicators are known. For example, the Applicant's previous patent, U.S. Pat. No. 4,163,427, which is incorporated by reference herein in its entirety, discloses an apparatus in which melting ice is used to activate a dye formation in producing a color indication of thawing. The present invention uses a pigment rather than a dye to indicate a transition over the threshold temperature. The use of a pigment allows for a greater clarity of indication, a reduced chance of error, and a reduction in manufacturing costs.
Another known device is marketed under the name “ColdMark Freeze Indicators.” This device comprises three liquids that provide a color change upon extended exposure below a certain temperature and another color change upon extended exposure above the temperature. However, this device is much larger than, and much more expensive than, the device of the present invention.
SUMMARY OF THE INVENTION
The present invention is a system and method for indication of temperature exposures beyond a set of predetermined limits employs the salts of weak acid-strong base or of a strong acid-weak base compound as reactants.



BRIEF DESCRIPTION OF THE DRAWINGS
A more complete understanding of the present invention may be obtained from consideration of the following description in conjunction with the drawings in which like reference characters reference like elements, and wherein:
FIG. 1 is a perspective view of a preferred embodiment of the indicator of the present invention;
FIG. 2 is a top view of the indicator of FIG. 1 indicating a safe condition;
FIG. 3 is a top view of the indicator of FIG. 1 indicating a transition from a temperature below the threshold temperature to a temperature above the threshold temperature;
FIG. 4 is a sectional view of the indicator of FIG. 1 taken along line 4-4;
FIG. 5 is a sectional view of another preferred embodiment of the indicator of the present invention;
FIG. 6 is a sectional view of another preferred embodiment of the indicator of the present invention;
FIG. 7 is a sectional view of another preferred embodiment of the indicator of the present invention; and
FIG. 8 is a sectional view of another preferred embodiment of the indicator of the present invention.
FIG. 9 is a perspective view of another preferred embodiment of the indicator of the present invention.



DETAILED DESCRIPTION OF VARIOUS ILLUSTRATIVE EMBODIMENTS
The present invention is a system and method for indication of temperature exposures beyond a set of predetermined limits. The apparatus of the present invention indicates a temperature transition condition using two reactants that combine to produce a pigment. A pigment is insoluble in the medium in which it is applied, while a dye is soluble. The use of a pigment is superior to the use of a dye since, for example, a pigment can produce a more brilliant color with smaller amounts of each reactant.
Additionally, pigment reactants are less likely to produce a color change with anything other than the complementary reactant.
A housing is provided, with one or more capsules are provided within the housing. As used herein, “capsule” refers to any closed receptacle and includes microcapsules. A first reactant and a liquid are provided inside the capsule. The liquid is chosen such that it expands upon freezing. The capsule is designed such that when the liquid freezes and expands, the capsule fractures. A second reactant is provided within the housing. The location of the second reactant and the means of coupling (if any) to the housing may take various forms. For example, the second reactant may take the form of a coating on the housing. The second reactant may also be mixed with an adhesive for coupling the second reactant to the housing. The second reactant may also take the form of a coating on the outside of the capsule. The second reactant may be coupled to a piece of material, such as paper, and the material placed inside the housing.
When the capsule and the liquid located therein freeze, the liquid expands. Since the capsule does not expand upon freezing, the expansion of the liquid fractures the capsule. When the capsule is subsequently thawed, the liquid melts, releasing the first reactant. The first and second reactants then combine to form a pigment. The pigment is a brilliant color that is chosen to be a different color than the housing, allowing a person viewing the changed condition indicator device to quickly and easily know whether the device has been previously frozen and thawed.
The device of the present invention may also be used as a high temperature indicator, either alone or in conjunction with the low temperature indicator embodiment as a dual indicator. The composition of the capsules may be altered such that the capsules will melt at a predetermined high temperature. When the capsules are raised to this temperature, they melt, releasing the enclosed reactant. The reactants then mix, forming a pigment.
The device of the present invention may be attached to any number of items in order to determine whether the temperature of items has been allowed to increase above a threshold temperature. Exemplary threshold temperatures include the freezing temperature and a temperature above which the item being monitored will be rendered ineffective. Exemplary preferred items to monitor include, but are not limited to, vaccines, other medications, food, and other temperature-sensitive items.
The device of the present invention may also be initiated manually. Rather than fracture via expansion upon freezing, the device of the current invention can be initiated by manually fracturing the capsule, thus allowing the device to be used as a time-temperature indicator.
The present invention is a system and method for indication of temperature exposures beyond a set of predetermined limits that involves two or more reactants which produce an irreversible color change when a thermal threshold is crossed. One or more of the reactants are incorporated in microcapsules and one or more of the reactants are in a coating, gel, or solution which is in direct contact with the microcapsules.
The microcapsules can be composed of paraffin wax, wax blends, natural plastics, synthetic resins, as well as a variety of other suitable compatible materials. The microcapsules have an interior variable volume and are of such size that the ratio of the interior volume to capsule wall volume can vary to provide proper mechanical and handling properties while meeting the thermal criteria requirements. Almost any shape or form of container can be used to seal the co-reactant systems together with the microcapsules.
Many of the reactants can be used for both high temperature conditions as well as low temperature conditions depending on the co-reactants used as coatings, gels and solvents which are in contact with the microcapsules.
One embodiment of the present invention is a system and method for indication of temperature exposures beyond a set of predetermined limits that employs the salts of a weak acid-strong base or of a strong acid-weak base compound as reactants, used together with different co-reactants and with different capsule walls to give both high temperature and low temperature indications with the same salt compound.
By varying the specific reactants, microcapsule wall compositions, and the specific design of the enclosure, a series of simple manufacturer items which indicate low temperature threshold, high temperature threshold, low and high temperature threshold, as well as exposure time temperature threshold can be manufactured on one type of machine.
An exposure time temperature threshold indicator is implemented using a whole series of enzymatic reactions and substrates together with flexible containers in conjunction with the microcapsule technique to separate the enzymes from the substrate until activated by bursting.
By incorporating together with the reactants, non-reactive colorless UV (Ultra Violet) fluorescing compounds within the walls of the microcapsules, the body of the container or both, a method of anti-counterfeiting protection is provided.
To more completely understand the range of reactants and indicators that can be used and incorporated into the present invention's system and method for indication of temperature exposures beyond a set of predetermined limits, tables 1 through 7 are provided. Table 1 represents alkali-metals, corresponding water soluble salts, resultant inorganic precipitants, and color of the precipitant.










TABLE 1







PRECIPITANTS.



Alkali-

Inorganic precipitants
Color of


Metals
Water Soluble Salts
*water soluble
Product







Potassium
KOH; KC2H3O2;
tests for potassium



(#19)
K2Al2O4•3H20;
1)*Sodium cobaltinitrite
1)yellow



KBOC4H4O6•1⁄2H2O; K2AsO4;
(solid)



KH2AsO4; KAsO2; K2HAsO4;
2)*Sodium cobaltinitrite
2)yellow



KAuCl4; K2B4O7•H2O; KBr;
(solid) and *silver



KBrO3; K2PtBr6; K2CO3;
nitrate



KHCO3; KCl; KClO; KClO3;
3)*Dipicrylamine
3)red



KClO4; K2CrO4; K2Cr2O7;
4)*sodium
4)white



KCN; KCNO; KAg(CN)2;
tetraphenylborate



K3Fe(CN)6; K4Fe(CN)6•3H2O;
5)all other tests are for
5)See



KF; KBF4; 3KF—AlF3; KI; KI3;
the various water soluble
individual



KIO3; KIO4; KMnO4;
salts of the particular
elements in the



K2MNO4; K2MoO4; KNO2;
elements involved as
water soluble



KNO3; K2C2O4•H2O; KOH;
indicted in the other
salts column



KH2PO4; K4P2O7; K2HPO3;
tables for that element



K3PO4; K2SiO3; K2SeO4; K2S5;



K2SO3;•2H2O; KHSO4; K2SO4;



K2S2O5; K2S2O7; K2S2O8;



KCNS; K2C4H2O6•1⁄2H2O;



K2WO4•2H2O; KReO4.


Rubidium
RbCO3; RbHCO3; Rb2CO3;
1)*LiDipicrylaminate
1)red


(#37)
RbCrO4; Rb2CrO4; RbF;
2)*AuBr3 + *H2PtBr6
2)black-brown



RbBr; RBrO3; RbCl; RbI;
3)*Na2AgBi(NO2)6
3)yellow



RbIO3; RbOH; RbNO3; Rb2S;



RbSO4; Rb2


Cesium
CsF; CsBr; CsBRO3; CsCl;
1)*AuBr3 + *H2PtBr6
1)deep black


(#55)
CsClO3; CsClO4; CsI; CsIO3;
2)*Potassium-bismuth
2)orange-



CsNO3; Cs2CO3
iodide
yellow




3)*AuCl3 + PdCl2
3)black-brown




4)*Sodium
4)black-brown




triphenyl(cyanoborate)


Lithium
LiC2O4; LiC2H2O2•2H2O;
1)Thoron
1)yellow


(#3)
LiHCO3; LiBr; LiBrO3; LiCL;
2)*Complex ferric
2)yellow-white



LiClO3; LiClO4; LiI; LiIO3;
periodate



LiHPO3; LiNO2; LiNO3;



LiOH; LiSCN; Li2CO3; Li2S;



Li2SO4; Li2SiO3; Li3(PO4)3


Sodium
NaC2H3O2; Na2C2O4; NaAlO2;
tests for sodium


(#11)
Na3AsO4•12H20;
1)*Zinc uranyl acetate
1)yellow



Na2HAsO4•12H2O;
2)*Zinc uranyl acetate
2)green-yellow



Na2HAsO3; NaBO2;
in ultraviolet light.
fluorescence



Na2B4O7•10H2O; NaBr;
3)Alpha-
3)white



NaBrO3; NaCO3•H2O;
Methoxyphenylacetic



Na2CO3•10H2O; NaHCO3;
acid



NaCl; NaClO•2.5H2O;
4)*Magnesium 8-amino-
4)dark grey



NaClO2; NaClO3; NaClO4;
1-



NaPtCl4•4H2O;
naphthalenesulfonate



Na2PtCl6•6H2O;
5)5-
5)orange-



Na2CrO4•10H2O;
benzamidoanthroquinone-
yellow



Na2Cr2O7•2H2O; NaCN;
2-sulfonic acid



NaCu(CN)2; NaFe(CN)6•H2O;
6)*potassium croconate
6)red



NaFe(CN)6•10H2O;
all other tests are for the
See the table



Na2Fe(CN)5NO•2H2O;
various water soluble
for the



NaCbO3; NaF;
salts of the particular
individual



3NaF-AlF3; NaCHO2; NaI;
elements involved as
elements in the



NaIO3; NaIO4;
indicated in the other
water soluble



NaMnO4•3H2O;
tables for those elements
salt column.



Na2MnO4•10H2O; Na2MoO4;



NaNO2; NaNO3; NaOH;



Na2C2O4; NaH2PO2•H2O;



NaHPO3•5H20; NaH2PO4•H2O;



Na2HPO4•12H2O;



Na2PO4•12H2O; Na3PO4;



Na4P2O7•10H20;



NaKCO2, 6H2O; NaReO4;



Na2SeO3; NaSeO4; NaSiO3;



Na2Si4O9; NaSn(OH)4; Na2S;



Na2S5; Na2SO3;



Na2S2O3•5H2O;



NaHSO4; Na2SO4;



Na2SO4•10H2O; Na2S2O5;



NaCNS; Na2C4H4O6•2H2O;



Na3VO4; Na2WO4;









Table 2 represents alkali earth metals, corresponding water soluble salts, resultant inorganic precipitants, and color of the precipitant.










TABLE 2





Alkali

PRECIPITANTS.



Earth

Inorganic precipitants
Color of


Metals
Water Soluble Salts
*water soluble
Product







Beryllium
BeBr2; BeCl2; BeI2;
1)Quinalizarin;
1)blue


(#4)
Be(ClO4)2;
2)p-Nitrobenzeneazoorcinol;
2)orange-red



Be(NO3)2•3H2O;
3)*Beryllon = [tetrasodium 2-(3,6-
3)light blue



BeC2O4•3H2O;
disulfo-8-hydroxynaphthylazo)-



BeSO4•4H2O
1,8-dihydroxynaphthalene-3,6-




disulfonate] = (Beryllon II);




4)Chrome Azural S;
4)blue-violet




5)Chrome Azural S + Cetyltrimethylammonium
5)blue




bromide;




6)Erichrome Cyanine R;
6)red




7)Erichrome Cyanine R + Cetyltrimethylammonium
7)red




bromide




8)Morin
8)green-yellow





fluorescence


Magnesium
Mg(C2H3O2)2•4H2O;
1)*Alkali hypoiodite;
1)brown


(#12)
MgBr2,
2)Quinalizarin;
2)blue



MgCl2•6H2O; MgI2,
3)p-Nitrobenzeneazo-alpha-
3)blue



Mg(NO3)2•6H2O;
naphthol;



MgSO3;
4)Titan Yellow;
4)flame red



MgSO4•7H2O;
5)p-Nitrobenzeneresorcinol.
5)blue



Mg(BrO3)2;
6)Eriochrome Black T
6)?



Mg(ClO3)2;
7)8-Hydroxyquinoline
7)?



Mg(ClO4)2;
8)8-Hydroxyquinoline + Butylamine
8)?



Mg(IO3)2;
Butylamine



MgCr2O7;
9)Xylidyl Blue
9)purple



Mg(NO2)2;
10)Chromotrope 2B
10)blue



MgS2O3.
11)*pentamethinedibarbituric acid
11)blue




12)*Ammonia + phenolphthalein
12)pink




13)Diphenylcarbizide
13)deep red


Calcium
Ca(C2H3O2)2•H2O;
1)Chlorophosphonazo III;
1)?


(#20)
CaBr2; CaCl2•6H2O;
2)Glyoxal-bis(2hydroxyanil);
2)blue



Ca(ClO3)2•4H2O;
3)Murexide;
3)?



Ca(ClO4)2; CaI2;
4)Phthalein Purple;
4?



Ca(IO3)2; CaCrO4;
5)*Ammonium ferrocyanide,
5)white



Ca(NO2)2;
6)*Dihydoxytartaric acid osazone
6)white flock



Ca(NO3)2•4H2O,
(solid)



Ca(MnO4)2•4H2O,
7)*Sodium rhodizonate. And
7)violet



Ca(H2PO2)2; CaSO4;
alkali hydroxide



CaSeO4•2H2O
8)Chloroindazone C
8)red-violet




9)*Ferric fluoride and *potassium
9)red




thiocyanate




10)Alizarin Red S and *Zirconium
10)red-violet




oxychloride




11)Calcichrome
11)blue


Strontium
Sr(OH)2;
1)*Sodium rhodizonate.
1)red-brown


(#38)
SrBr2•6H2O;



Sr(BrO3)2;



SrCl2•6H2O,



Sr(ClO2)2; Sr(ClO3)2;



SrI2•6H2O; Sr(IO3)2;



Sr(NO2)2•4H2O;



Sr(NO3)2;



SrS2O5.


Barium
BaO; Ba(OH)2;,
1)*Sodium rhodizonate;
1)red-brown


(#56)
BaBr2•2H2O,
2)Tetrahydroxyquinone + KCl;
2)red (acid)



Ba(BrO3)2;
3)*Sulfonazo III
3)blue-green



BaCl2•2H2O;
4)*Induction of precipitation of
4)white



Ba(ClO2)2;
lead sukfate



Ba(ClO3)2•2H2O;
5)*Potassium permanganate and
5)violet



Ba(ClO4)2, BaI2,
*sodium sulfate



Ba(NO2)2;
6)Nitro-3-hydroxybenzoic acid
6)red ring



Ba(NO3)2;



Ba(MnO4)2;



BaH4(PO4); BaS;



Ba(SCN)2; BaC2O4;



Ba(C2H3O2)•2H2O.









Table 3 represents transition elements, corresponding water soluble salts, resultant inorganic precipitants, and color of the precipitant.










TABLE 3







PRECIPITANTS.



Transition

Inorganic precipitants
Color of


Element
Water Soluble Salts
*water soluble
Product







Fourth Row





Scandium
ScCl3, ScBr3, Scl3,
1)Tetrahydroxyflavanol
1)green


(#21)
Sc2(SO4)3, Sc(NO3)3
(“Morin”);
flourescence




2)*Alizarin red S;
2)?;




3)*Xylenol Orange;
3)?;




4)Arsenazo III;
4)?;




5)Chrome Azural S.
5)?.




6)Methylthymol Blue
6)deep blue


Titanium
TiCl2; TiCl3.; TiCl4
1)*Pyrocatechol,
1)yellowish-


(#22)
TiK2F6,

red



Ti2(C2O4)3•10H2O,
2)*Chromotropic Acid;
2)brown-red



TiO(C2O4K)2•2H2O,
3))*Chromotropic Acid + conc.
3)violet



Ti(SO4)2•9H2O,
*Sulfuric acid



TiOSO4•H2SO4•8H2O
4)*Tiron;
4)orange-red




5)*Hydrogen peroxide;
5)yellow




6)*Tannin + antipyrine;
6)red




7)Diantipyrinylmethane.
7)?




8)*Methylene blue and zinc.
8)discharge of





methylene blue




9)Acetylacetone
9)Ti (III) - red





Ti (IV) -





yellow




10)Morin
10)brown




11)*Alizarin Red S and zinc
11)green




12)Resoflavine
12)red-orange




13)Tetraphenylarsonium
13)yellow




chloride




14)Tetraphenylphosphonium
14)yellow




chloride




15)Benzyl 2-hydroxyphenyl
15)yellow




ketone




16)Ammonium hypophosphite melt
16)blue


Vanadium
Na(C6H14O3)2V(CO)6*,
1)*Cacotheline;
1)violet


(#23)
V2O2Cl4•5H2O,
2)8-Hydroxyquinoline;
2)blue-black



VOSO4•2H2O, VCl2,
3)Aniline;
3)aniline black



VCl3, VCl4.
4)Phosphomolybdic acid;
4)molybdenum





blue




5)*Hydrogen peroxide;
5)red-brown to





blood red.




6)N-Benzoyl-N-
6)?




phenylhydoxylamine;




7)4-(2-pyridylazo)resorcinol.
7)?




8)*Reduction of ferric salts by
8)red




tervalent vanadium




9)alpha-Benzoinoxime
9)yellow




10)3.3′-Dimethylnaphthidine
10)blue-violet




11)Quercetin
11)green




12)2-(salicylideneimino)benzoic
12)violet




acid




13)Sulphosalicylic acid and
13)blue




*phosphoric acid




14)*Koji acid
14)red-brown




15)*8-Hydroxy-7-iodoquinoline-
15)green




5-sulfonic acid (“Ferron”)




16)Resorcinol and *syrupy
16)deep blue




phosphoric acid
(fluoresces red





under U, V,)




17)*Ammonium hypophosohite
17)green




melt


Chromium
Cr(C2H3O3)3•H2O,
1)1,5-Diphenylcarbizide (for
1)violet (alk.)


(#24)
CrO3,
chromates, alkaline);
to red



CrCl3•6H2O,
2)4-(2-Pyridylazo)resorcinol;
2)?



CrF3•4H2O, CrF3•9H2O,
3)4-(2-Pyridylazo)resorcinol + *Tetradecyldimethylbenzyl-
3)?



Cr(OH)(HCOO)2,
ammonium chloride;



CrF3•9H2O,
4)*Acetic acid Benzidine (for
4)blue



Cr(OH)(HCOO)2,
chromates) solution;



Cr(NO3)3•9H2O,
5)Acid Alizarin RC;
5)orange lake



Cr(NO3)3•9H2O,
6)*Silver nitrate (for chromates);
6)red



CrSO4•7H2O,
7)*Lead acetate (for chromates);
7)yellow



Cr2(SO4)3•15H2O,
8)4-(2-Pyridylazo)resorcinol + *Hydrogen
8)?



Cr2(SO4)3•18H2O,
peroxide.



CrNH4(SO4)2•12H2O,
9)Chromotropic acid
9)brown-red



CrK(SO4)2•12H2O,
10)1,2-diaminocyclohexane-
10)reddish-



CrBr2, CrCl2, CrCL3,
N,N,N′N′-tetraacetic acid
violet



CrC2O4•H2O,
11)Diphenylcarbizide + phthalicanhydride
11)violet




12)2,7-Diamino-diphenylene
12)blue




oxide




13)Sel-K5 exchange resin
13)red-





violet(Cr+6)




14)*Hydrogen peroxide + cation
14)gray, violet-




exchange resin(Amberlite
blue,




IRA-4II [Cl— form 30 mesh)
or violet brown




15)Methyl violet
15)deep blue




16)Pyrrole
16)“pyrrole





blue”




17)Strychnine
17)blue-violet





to red




18)Ammonium hypophosphite
18)green




melt


Manganese
Mn(C2H3O2)2•4H2O,
1)*Formaldioxime hydrochloride;
1)orange-red


(#25)
MnSO4•(NH4)2SO4•6H2O,
2)a)*Periodate;
2)a)violet



MnSO4•(NH4)2SO4•6H2O,
b)*Periodate + tetrabase;
b)blue



Mn3(C6H5O7)2,
3)Alkali hydroxide + benzidine;
3)blue



MnS2O6,
4)*Ammoniacal silver nitrate
4)black



Mn(C6H11O7)2•2H2O,
5)Sodium perxenate(solid)
5)violet to pink



CH2OHCHOHCH2OP(O)O2Mn,
6)Benzidine
6)blue



Mn(H2PO2)•H2O,
7)*Tollens reagent
7)black



Mn(C3H5O3)2•3H2O,
8)Lead dioxide
8)violet



MnBr2, MnCl2,



MnCl2•4H2O,



Mn(IO3)2;



Mn(NO3)2•6H2O,



MnSO4•5H2O, Mn2O7


Iron (#26)
Ferric ammonium
1)*8-hydroxyquinoline-7-iodo-5-
1)green



citrate,
sulfonic acid;



(NH4)3Fe(C2O4)3•3H2O,
2)Potassium ferrocyanide;
2)prussion blue



FeNH4(SO4)2•12H2O,
3)Alpha,alpha′-Dipyridyl;
3)deep red



ferric ammonium
4)Potassium thiocyanate;
4)deep red



tartrate, FeF3, FeBr2,
5)Dimethylglyoxime
5)red



FeCl2, FeCl3,
6)*Sodium dimethylglyoxime
6)red



Fe(ClO4)2,
7)*Disodium-1,2-
7)pH <5 deep



Fe[(CH3)2AsO2]3,
dihydroxybenzene-3,5-
blue, pH 5.7 to



FeC6H5O7•2H2O,
disulfonate;
6.5 violet,



Fe2(Cr2O7)3,

pH7red.



Fe[C3H5(OH)2PO4]3•xH2O,
8)*Thioglycolic acid;
8)purple-red



Fe2(C4H4O5)2,
9)*Quercitrin;
9)olive green



Fe(NO3)2,
10)*2-Nitroso-1-naphthol-4
10)green



Fe(NO3)3•9H2O,
sulfonic acid.



FeSO4, Fe2(C2O4)3,
11)*Sodium Phosphate;
11)Yellow-



ferric potassium citrate,

white



ferric pyrophosphate
12)Bathophenanthroline;
12)red



soluble (A combination
13)* Bathophenanthroline
13)red



of ferric pyrophosphate
disulfonic acid;



(Fe4(P2O7)3•xH2O) and
14)Ferene;
14)?



sodium citrate).
15)Chrome Azurol S + *Cetyltrimethylammonium
15)?




bromide;




16)1,10-Phenanthroline;
16)red




17)1,10-Phenanthroline + Bromothymol
17)?




Blue;




18)*Ferrozine
18)?




19)Isonitrosobenzoylmethane
19)blue




20)Phenyl 2-pyridyl ketoxime
20)violet




21)Pyridine-2,4,6-tricarboxylic
21)purple




acid




22)5,7-Dibromo-8-
22)green-black




hydroxyquinoline




23)Quercetin or quercitin
23)olive-green




24)Alpha-Furil monoxime
24)red




25)p-Amino-N,N-dimethylaniline
25)rose




26)o-Phenylenediamine
26)yellow to





red


Cobalt (#27)
Co(C2H3O2)2•4H2O,
1)Alpha-nitroso-beta-naphthol;
1)red-brown



CoSO4•(NH4)2SO4•6H2O,
2)Beta-Nitroso-alpha-naphthol;
2)red-brown



CoBr2•6H2O, CoCl2,,
3)Rubeanic acid;
3)yellow-



CoCl2•6H2O,

brown



Co(ClO4)2,
4)*Ammonium Thiocyanate and
4)deep blue



CoF2, Co(CHO2)2•2H2O,
acetone;



CoI2•6H2O, Co(NO2)2,
5)*2-Nitroso-1-naphthol-4-
5)red



Co(NO3)2,
sulfonic acid.



CoSiF6•6H2O, CoSO4,
6)*Nitroso R salt;
6)red



CoSO4•7H2O,
7)4-(2-Pyridylazo)resorcinol;
7)?



K3Co(NO2)6,
8)4-(2-Pyridylazo)resorcinol + Diphenylguanidine;
8)?



Co(SCN)2
9)*Sodium thiosulfate
9)blue




10)Chromotropic acid dioxime
10)blue




11)*Sodium
11)greenish-




pentacyanopiperidine ferrate
blue




12)*Hydrogen peroxide and
12)green




*sodium bicarbonate




13)*Mangabous sulfate &
13)brown




butyraldehyde




14)*Sodium azide & o-tolidine
14)blue




15)Diacetylmonoxime p-
15)violet or




nitrophenyl-hydrozone
purple




16)3-Hydroxyiminopentane-2-
16)red




one




p-nitrophenylhydrozone




17)Ammonium hypophosphite
17)blue




melt


Nickel (#28)
Ni(OOCCH3)2•4H2O,
1)Dimethylglyoxime;
1)Red ppt.



NiF2, NiCl2•NH4Cl,
2)*Sodium Dimethylglyoxime;
2)Red ppt;



Ni(ClO4)2,
3)Dimethylglyoxime and
3)Red to



NiCl2•NH4Cl•4H2O,
bromine water;
orange



NiBr2, NiBr2•3H2O,
4)Rubeanic Acid (dithiooxamid);
4)blue to blue



NiCl2, NiCl2•6H2O,

violet;



NiI2,
5)2,2′-Furildioxime;
5)?



(HCOO)2Ni•2H2O,
6)2-(5-Bromo-2-pyridylazo)-
6)?



Ni(NO3)2•6H2O,
diethylaminophenol;



Ni(NO3)2,
7)2-(2-Pyridylazo)-2-naphthol;
7)?



Ni(NO3)2•4NH3•2H2O,
8)4-(2-Pyridylazo)resorcinol;
8)?



NiSO4•K2SO4•6H2O,
9)*4-(2-Pyridylazo)resorcinol
9)?



NiSO4•6H2O,
sodium salt;



NiSO4•7H2O;
10)Quioxaline-2.3-dithiol
10)red



Ni(SCN)2


Copper
Cu(C2H3O2)2•H2O,
1)Benzoin oxime
1)green


(#29)
CuBr2, CuCl2,
2)* 4)Salicylaldoxime;
2)yellow-green



CuCl2•2H2O,
3)o-Tolidene and *ammonium
3)light to dark



Cu(ClO4)2,
thiocyanate;
blue



CuCr2O7•2H2O,
4)*Phosphomolybdic acid;
4)deep blue



CuSiF6•4H2O,
5)*1,2-Diaminoanthraquinone
5)blue



[CH2OH(CHOH)4COO]2Cu,
sulfonic acid;



Cu(C3H5O3)2•2H2O,
6)Rubeanic acid;
6)black



Cu(NO3)2•3H2O,
7)Dithizone;
7)yellow-



Cu(NO3)2•6H2O,

brown



[C6H4(OH)SO3]2Cu•6H2O,
8)Benzidine + *potassium
8)blue



CuCl2•2NaCl•2H2O,
bromide;



CuSO4•5H2O,
9)p-Dimethylaminorhodanine;
9)red



Cu(NH3)4SO4•H2O,
10)8-hydroxyquinolline + *potassium
10)red



CuSeO4
cyanide;




11)*Ammonium mercury
11)violet




thiocyanate + *zinc salts;




12)*Hydrobromic acid;
12)violet to





brown.




13)*2-Nitroso-1-naphthol-4-
13)orange(pH




sulfonic acid.
7-8)




14)Phennetidine + hydrogen
14)violet




peroxide;




15)Diphenylcarbazone;
15)violet




16)Di-m-nitrophenylcarbazone;
16)violet




17)Bathocuproine;
17)?




18)* Bathocuproine disulfonic
18)?




acid;




19)Neocuprine;
19)?




20)Cuprizone
20)?




21)*Potassium ferrocyanide
21)brick red




22)Zinc ferrocyanide
22)brick red




23)*Sodium
23)brown




diethyldithiocarbamate




24)Zinc diethyldithiocarbamate
24)brown-





yellow




25)2,2′-Biquinoyl (Cuproin)
25)purple-red




26)*Catalysis of the ferric-
26)deep violet




thiosulfate reaction




27)p-Phenylenediamine &
27)black




*ammonium thiocyanate(on




Dowex 50-X or 1% DVB)




28)Alizarin Blue
28)cornflower-





blue




29)*Ammonium bromide &
29)violet




*Concentrated Phosphoric acid




30)Alkali tartrate, *hydrogen
30)indigo blue




peroxide &




o-hydroxyphenylfluorone




31)Catalysis of the autoxidation
31)brown




of resorcinol




32)Benzamiidoxime
32)green




33)Acetylene
33)intense red




34)Lumocupferron
34)green





fluorexcence




35)Potassium guaiacol-o-sulfate
35)greenish-





yellow




36)8,8′-Diquinolyldisulfide
36)?


Zinc (#30)
Zn(C2H3O2)2•2H2O,
1)*Potassium ferricyanide and
1)yellow to



ZnF2, ZnCl2•2NH4Cl,
diethyl aniline;
brownish red



ZnO 45% B2O3 34%
2)Dithizone
2)purple-red



may have 20% water of
3)*Potassium ferricyanide + p-
3)blue



hydration,
phenetidine;



Zn(BrO3)2•6H2O,
4)Uranyl ferrocyanide;
4)white on



ZnBr2,

brown



Zn(ClO3)2•4H2O,
5)Resorcinol.
5)blue



ZnCl2, Zn(ClO4)2, Zinc
6)1-(2-Pyridylazo)-2-naphthol
6)?



chloroiodide (A
7)*Xylenol Orange
7)?



mixture of chloride and
8)Zircon
8)?



iodide),
9)*Potassium ferricyanide and
9)dark red-



Zn(C2H5SO4)2•2H2O,
3.3′-dimethylnaphthidine
brown



ZnSiF6•6H2O,
10)Induced precipitation of
10)blue



Zn(HSO2•CH2O)2
Co[Hg(CN)4}



(normal),
11)Trisodium pentacyano-p-
11)pale green



Zn(CHO2)2•2H2O, Zinc
nitroso-dimethylanilino-ferrate(II)
to blue



gluconate,
12*Potassium cobalticyanide
12)green



C3H5(OH)2OPO3Zn,
13)Vanillinazin
13)dark red



ZnS2O4, Zn(OH)2,
14)*Potassiumferricyanide and
14)blue



Zn(H2PO2)2•H2O, ZnI2,
methylene blue



Zn(IO3)2,
15)*Potassiumferrocyanide,
15)violet



Zn(C3H5O3)2•3H2O,
*thiourea, and Rhodamine B



Zn(OOCCH2CHOHCOO)•3H2O,
16)*Potassiumferrocyanide and
16)yellow



Zn(NO3)2•6H2O,
methyl violet



Zn(MnO4)2•6H2O,
17)4-aminobenzenethiol
17)rose



Zn(SO3C6H4OH)2•8H2O,
18)*Potassiumferrocyanide,
18)deep blue



Zn(OOC2H5)2,
*potassium iodide and starch



Zn[C6H4(OH)COO]2•3H2O,



ZnSO4•7H2O,



ZnSO4•H2O,



Zn(CNS)2, “Calgon



composition TG”(a



glassy composition of



sodium zinc



hexametaphosphate).



ZnSeO4


Fifth Row


Ytrium
Y(C2H3O2)3•8H2O,
1)*Alizarin Red S;
1)?


(#39)
YBr3•9H2O,
2)Arsenzo III;
2)?



YCl3•6H2O, Y(NO3)3
3)*Xylenol Orange.
3)?




4)Catechol and organic bases
4)white




5)Complex of catechol violet
5)blue




with *boric acid


Zirconium
H2ZrO2(C2H3O2)2
1)2-Nitroso-1-naphthol;
1)green-yellow


(#40)
available as 22% and
2)1-Nitroso-2-naphthol;
2)red



13% ZrO2 aqueous
3)Alizarin;
3)red brown to



solutions, Zr(NH4)2F6,

dark violet



H4ZrO(CH3CHOCO2)3,
4)p-
4)brown



Zr(NO3)4•5H2O,
Dimethylaminoazophenylarsonic



ZrOCl2, 8H2O, ZrK2F6
acid;



(hot), Zr(SO4)2•4H2O,
5)a)*Carminic acid
5)a)yellow to



ZrOOHCl•nH2O,

red,



ZrO(OH)NO3.
[or} b)gallocyanine];
b)pink to blue




6)5-Chlorobromoamine acid;
6)red




7)*Alizarin Red S;
7)?




8)Arsenazo III;
8)?




9)*Xylenol Orange.
9)?




10)m-(2-Hydroxynaphthalene-1-
10)pink




azo)-mandelic acid


Niobium
NbO(HC2O4)3•4H2O,
1)N-Benzoyl-N-
1)?


(#41)
K2NbOF5•H2O.
phenylhyroxylamine;




2)*Pyrocatechol + EDTA;
2)?




3)2,2′-Bipyridil;
3)?




4)1-(2-thenoyl)-3.3.3-
4)?




trifluoroacetone;




5)Bromopyrogallol red;
5)?




6)Bromopyrogallol red + Cetylpyridinium
6)?




chloride;




7)4-(2-Pyridylazo)resorcinol;
7)?




8)Sulfochlorophenol S;
8)?




9)*Xylenol Orange.
9)?




10)*Pyrpgallol-4-sulfonic acid
10)orange-





orange red




11)Ammonium hypoohosphite
11)black




melt




12)*Zinc chloride
12)blue-black


Molybdenum
H4SiMo12O40•xH2O x = usually
1)Phenylfluorone;
1)?


(#42)
6-8,
2)Bromopyrogallol Red + Cetylpyridinium
2)?



Heteromolybdates such
chloride;



as Na3PMo12O40 (can
3)Toluene-3,4-dithiol,
3)?



contain phosphorous,
4)*Potassium thiocyanate + stannous
4)brick red



arsenic, iron, and
chloride;



tellurium as hetero
5)*Potassium xanthate;
5)pink to violet



atoms and any of 35
6)*Zinc or *cadmium xanthate;
6)red



elements can be
7)Phenylhydrazine;
7)blood red



present. The acids and
8)Tincture of cochineal;
8)Flame red



most of the salts are

fluorescence



very soluble,

(pH 5.7-6.2)



Na2MoO2,
9)Alpha,alpha′-Dipyridil + *stannous
9)violet



Na4SiMol2O40, MFP.
chloride;




10)Diphenylcarbazide;
10)violet




11)Di-beta-naphthylcarbazone
11)violet




12)*Potassium ethyl xanthate
12)deep red-





blue




13)Zinc ethyl xanthate
13)deep red-





blue




14)Methylene blue and hydrazine
14)Fading of





blue




15)o-Hydroxyphenylf; uorone
15)carmine




16)Morin and butanol
16)brown




17)Ammonium hypophosphite
17)red-brown




melt


Ruthenium
Ru2(OH)2Cl4•7NH3•3H2O,
1)1,10-Phenanthroline;
1)?


(#44)
RuCl3.
2)*Thiourea;
2)?




3)1,4-Diphenylthiosemicarbazide;
3)?




4)*Potassium chlorate + potassium
4)blue black




iodide (+starch);




5)Rubeanic acid;
5)blue




6)Benzidene;
6)blue or green




7)*Potassium ferrocyanide.
7)blue or green


Rhodium
RhCl3(if hydrated),
1)1-(2-Pyridylazo)-2-naphthol
1)?


(#45)
Rh(NO3)2•2H2O,
2)*Stannous chloride + *ammonium
2)cherry red



Rh(SO4)2•12H2O,
chloride and




*potassium iodide


Palladium
PdCl2, PdCl2•2H2O,
1)*Mercuric cyanide + *Stannous
1)orange-red to


(#46)
Pd(NO3)2, PdCl2•2KCl,
chloride.
yellow gold



PdCl2•2NaCl,
2)Nickel dimethylgloxime;
2)pink to red




3)Naphthalene-4′-sulfonic acid-1-
3)orange-




azo-5-o-8-hydroxyquinoline;
yellow




4)p-Dimethylaminobenzylidene
4)red-violet




rhodanine;




5)Diphenylcarbazide and
5)violet




*mercuric cyanide;




6)2-(5bromo-2-pyridylazo)-5-
6)?




diethylaminophenol;




7)Dithizone;
7)?




8)2-Nitroso-1-Napthol;
8)?




9)4-(2-Pyridilazo)resorcinol
9)?




10)*Mercuric iodide
10)black or





grey




11)p-Nitrosophenylamine
11)red or





purplish brown




12)Phenooxithine
12)yellow to





red brown




13)3-Hydroxy-3-phenyl-1-sulfo-
13)?




phenyltriazene




14)Mercaptobenzoindazole
14)orange




15)*Mercuric cyanide and methyl
15)red




yellow




16)Parafuchsin
16)brown




17)Alpha-nitroso-beta-naphthol
17)dark-brown




18)Potassium ferrocyanide and
18)red




alpha-alpha′-dipyridyl




19)Triphenylstilbene
19)pink to red




20)Voluric acid
20)yellow-





brown




21)Ammonium molybdate and
21)blue




sodium hypophosphate


Silver (#47)
AgF•H2O, AgNO2,
1)Dithizone;
1)violet



AgNO3, KAg(CN)2,
2)*Eosin + 1,10Phenanthroline;
2)?



Ag2S2O3•2Na2S2O3•2H2O,
3)Methylthymol blue + *Barium
3)?



Ag2SO4 (hot), AgClO2,
(II) (Sulfate)



AgClO3, AgClO4,
4)N,N,-Dimethyl-1,4-
4)?




phenylenediamine (Sulfide);




5)Pararosaniline + *Formaldehyde
5)?




(Sulfite);




6)*Manganese Nitrate and alkali;
6)black




7)p-Dimethylaminobenzylidene
7)red violet




rhodanine;




8)*Potassium Chromate;
8)red




9)*Stannous chloride and
9)black




chromotropic acid;




10)*Stannous Chloride
10)free silver




11)*Sodium selenosulfate
11)brown




12)*Persulfate and pyridine
12)yellow




13)1,10-Phenanthroline and
13)blue




bromo-pyrogallol red




14)*Cuprous thiocyanate
14)smoke-





brown




15)p-
15)red violet




Dimethylaminobenzylidenethio-




barbituric acid




16)Ethylenediaminetetraacetic
16)black or




acid + *FeSo4 + *sodium acetate
grey




17)Potassium ferrocyanide and
17)red




alpha,alpha′-dipyridyl




18)Potassium nickel cyanide and
18)red




dimethylglyoxime


Cadmium
Cd(OOCCH3)2•3H2O,
1)Dithizone;
1)?


(#48)
CdF2, CdBr2•4NH4Br,
2)Cadion;
2)?



Cd5(BW12O40)•18H2O,
3)2-(5-Bromo-2-pyridylazo)-5-
3)?



CdBr2, CdBr2•4H2O,
diethylaminophenol;



Cd(ClO3)2•2H2O, CdCl,
4)4-(2-Pyridylazo)rersorcinol;
4)?



CdCL2•2.5H2O,
5)Di-p-nitrophenylcarbazide:
5)green-blue



Cd(ClO4)2,,
6)Ferrous dipyridyl iodide;
6)red-violet



CdI2(alpha), Cd(NO3)2•4H2O,
7)Di-beta-naphthylcarbazone;
7)red to violet



Cd(NO3)2,
8)Diphenylcarbazide;
8)violet



CdI2•2KI•2H2O, CdSO4,
9)p-Nitrodiazoaminoazo benzene
9)bright pink



3CdSO4•8H2O,
(Cadion 2B)



CdSO4•4H2O, CdSeO4
10)*Sodium Sulfide
10)yellow




11)Zinc Sulfide
11)yellow




12)Glyoxal bis-(2-hydroxyanil)
12)blue




13)*Cyanide and *sodium sulfite
13)yellow




14)Bis-(p-
14)intense




ethylbenzylaminophenyl)-
crimson




antipyrinyl-methanol




15)Dithizone and cyclohexanone
15)orange


Sixth Row


Lanthanum
La(C2H3O2)3•xH2O,
1)Arsenzo III.
1)?


(#57)
La(NO3)3 × 2NH4NO3 × 4H2O,
2)Acid Monochrome Bordeaux S
2)orange



LaCl3•7H2O,



La(NO3)3•6H2O.


Hafnium
HfOCl2•8H2O,
1)Arsenzo III.
1)?


(#72)
K2HfF6, HfBr4, HfCl4.
2)Arsenzo I
2)red-violet




3)Quercetin and *perchloric acid
3)green





fluorescence





(UV)


Tantalum
Na8Ta6O19•25H2O,
1)*Methyl Violet;
1)?


(#73)
K2TaF7(hot).
2)4-(2-Pyridylazo)resorcinol;
2)?




3)Phenylfluorone
3)?




4)Catechol violet
4)blue-violet




5)*Pyrogallol-4-sulfonic acid
5)yellow




and *oxalic acid


Tungsten
See Hetromolybdates
1)*Pyrocatechol Violet;
1)?


(#74)
for heterotungstates,
2)*Tetraphenylarsonium chloride + *Thiocyanate;
2)?



especially
3)Toluene 3,5-dithiol;
3)?



phosphotungstates such
4)*Stannous chloride;
4)blue



as H3PW12O40•xH2O,
5)Diphenylene.
5)white ppt.



Na2WO4•2H2O, WCl5,
6)8-Hydroxyquinoline
6)orange



WBr5,

yellow



(NH4)6W7O24•6H2O,
7)Ammonium hypophosphite
7)blue



K2WO4•2H2O,
melt



2(NH4)3PO4•24WO3•xH2O,



(NH4)6H2W12O40•xH2O


Rhenium
Re2O7, ReCl3, ReO3,
1)2.2′-Furildioxime.
1)?


(#75)
NaReO4.
2)*Tris(alpha,alpha′-dipyridyl)-
2)red




iron(II)sulfate


Osmium
OsO4, (NH4)2OsCl6.
1)1.5-Diphenylcarbazide;
1)?


(#76)

2)*Potassium chlorate + potassium
2)blue




iodide + starch;




3)*Benzidene acetate;
3)blue or green




4)Potassium ferrocyanide.
4)blue or





green




5)3.3′-Dimethylnapthidine
5)red




6)Apomorhine
6)brownish-red




7)p-Phenylenediamine
7)violet-red


Iridium
IrCl2, IrCl•xH2o,
1)Rhodamine 6G + Tin(II);
1)?


(#77)
IrCl4•2NH4Cl,
2)N,N-Dimethyl-4-
2)red



Ir3•3NH4Cl,
nitrosoaniline.



Ir2(SO4)•3(NH4)2SO4•24H2O,
3)a)Alizarin or
3)a)dark red,



IrCl4, IrBr3•4H2O,
b)Quinalizarin
b)violet



K2IrCl6.
4)Benzidine
4)blue


Platinum
(NH4)2PtCl6,
1)Dithizone;
1)?


(#78)
H2PtCl6•6H2O,
2)2-Mercaptobenzothiazole;
2)?



BaPt(CN)4•4H2O,
3)Sulfochlorophenolazorhodamine
3)?



PtCl4, PtCl4•5H2O,
4)*Thallium nitrate* + *Stannous
4)yellow to



PtCl4•8H2O,
chloride.
orange red



Na2PtCl4•4H2O
5)*Alkali iodide
5)brown



Na2PtCl6•6H2O,
6)1.4.-Diphenyl-3-
6)green



Pt(SO4)2•4H2O, PtI4.
thiosemicarbazide


Gold (#79)
Au(CN)33H2O,HAu(CN)4•3H2O,
1)*Rhodamine B;
1)red-violet



NaOOCCH(SAu)CH2COONa•H2,
2)5-(4-
2)red-violet



AuCl3,
Diethylaminobenzylidene)



AuCl3•2H2O,
rhodanine;



AuCL2•HCl•4H2O,
3)Benzidene.
3)blue



HAuCl4•4H2O,
4)Alpha-Naphthylamine and
4)violet



NaAuCl4•2H2O,
butanol



NaAu(CN)2, AuBr3,
5)N,N′-di-2-naphthyl-p-
5)red-brown



HAuBr4•5H2O,
phenylene-diamine



Au2O3•2SO3•H2O,



HAu(NO3)4•3H2O.


Mercury
Hg(C2H2O2)2,
1)Diphenylcarbazone);
1)blue or


(#80)
HgCl2•2NH4Cl•2H2O,

violet



HgBr2•BaBr2,
2)*Xylenol Orange;
2)?



HgI2•BaI2•5H2O, HgCl2,
3)Michler's thioketone;
3)?



Hg(CN)2, HgF2,
4)*Stannous chloride and
4)grey or black



Hg(C3H5O3)2,
aniline;



Hg(NO3)2•2H2O,
5)p-Dimethylaminobenzylidene
5)violet



Hg(NO3)2•1⁄2H2O,
rhodanine;



HgO•Hg(CN)2,
6)*Copper(I) iodide;
6)



Hg(CN)2•2KCN,
7)*Chromotropic acid.
7)brown or



K2HgI4 or 2KI•HgI2,

yellow



“merbromin”C20H8Br2
8)Dithizone
8)orange



HgNa2O6, mercurol
9)Potassium ferrocyanide + nitrosobenzene
9)violet



(contains 20%
or other nitrosos



mercury), Hg2(ClO3)2,
10)Chromotropic Acid
10)brown or



HgSO4

yellow




11)Potassium ferrocyanide and
11)red




alpha,alpha′-dipyridyl




12)Glyoxal bis-(2-mercaptoanil)
12)dark red to





pale pink




13)Ammonium sulfide
13)?









Table 4 represents metals, corresponding water soluble salts, resultant inorganic precipitants, and color of the precipitant.










TABLE 4







PRECIPITANTS.





Inorganic precipitants
Color of


Metals
Water Soluble Salts
*water soluble
Product







Aluminum
Al(ClO3)2•6H2O;
1)*Alizarin Red S;
1)red


(#13)
Al(ClO4)3; AlF3;
2)*Aluminon;
2)red lake



AlCl3; AlI3;
3)*Aluminon + *Cetyltrimethyl-
3)red



Al(NO2)3•9H2O;
ammonium bromide;



Al(NO3)3; Al2(SO4)3;
4)Chrome Azurol S;
4)blue



AlNH4(SO4)2•12H2O;
5)Chrome Azurol S + *Cetyltrimethyl-
5)orange



AlTl(SO4)2•12H2O;
ammonium



AlK(SO4)2•12H2O.
bromide;




6)Chromazol KS + *Cetylpyridinium
6)violet




bromide;




7)*Eriochrome Cyanin R;
7)violet




8)*Eriochrome Cyanin R + *Cetyltrimethylammonium
8)violet




bromide;




9)8-Hydroxyquinoline;
9)yellow-green





fluorescence




10)Morin and Morin under U.V.
10)intense




light;
green





fluorescence




11)Alizarin sulfonic acid;
11)red




12)Alizarin;
12)deep violet




13)Qunalizarin;
13)red to red-





violet




14)Pontachrome blue black R;
14)orange-red





fluorescence




15)*Ammonium aurin
15)red lake




tricarboxylate (“Aluminon”)




16)Tannin
16)?




17)Chrome Fast Pure Blue B
17)magenta or





pink




18)Salicylidene-o-aminophenol
18)yellow-





greenish





fluorescence




19)Glyoxal bis-(2-hydroxyanil)
19)red


Gallium
GaCl2; GaCl3;GaBr3.
1)*Pyrocatechol violet + Diphenylguanidine;
1)?


(#31)

2)8-Hydroxyquinoline;
2)?




3)1-(2-Pyridylazo)-2-naphthol;
3)?




4)4-(2-Pyridylazo)resorcinol;
4)?




5)Rhodamine B;
5)?




6)*Xylenol Orange;
6)?




7))*Xylenol Orange; + 8-
7)?




Hydroxyquinoline;




8)*Potassium ferrocyanide and
8)red-brown




*manganese chloride




9)Salicylidene-o-aminophenol + *NaBF4
9)yellow





fluorescence





(UV)




10)Rhodamine S
10)fluorescence





(UV)




11)*Gallion
11)blue





fluorescence





(UV)




12)Lumogallion
12)orange





fluorescence





(UV)




13)Eriochrome Red B
13)blue





fluorescence





(UV)


Germanium
GeF4•2H2O
1)Brilliant Green + *Molybdate;
1)


#(31)

2)Phenylfluorone;
2)




3)*Ammonium molybdate and
3)blue




benzidene;




4)Hydroxyanthroquinone
4)a)yellowish-





red,





b)orange-wine





red





c)violet-blue




5)9-Phenyl-2,3,7-trihydroxy-6-
5)pink




fluorone




6)Haematoxylin and anion
6)violet to black




exchange resin(Amberlite




IRA-411)




7)Diphenylcarbazone
7)purple




8)*Ammonium molybdate and
8)evanescent




*hydoxylamine hydrochloride
blue-green


Indium (#49)
InCl3; InI3; In2(SO4)3
1)Bromopyrogallol Red;
1)?




2)Chrome Azurol S;
2)?




3)Chrome Azurol S + Cetyltrimethylammonium
3)?




bromide




4)Dithizone
4)?




5)8-Hydroxyquinoline
5)?




6)1-(2-Pyridylazo)-2-naphthol
6)?




7)4-(2-Pyridylazo)resorcinol;
7)?




8)Alizarin
8)dark red




9)Quinalizarin
9)violet


Tin (#50)
H2SnCl6•6H2O;
1)*Pyrocatechol violet
1)?



SnBr2;
2)*Pyrocatechol violet + *Cetyltromethylammonium
2)?



SnCl2; •2H2O; SnSO4;
bromide



Sn(SO4)2•2H2O.
3)Gallein
3)?




4)Phenylfluorone
4)?




5)Toluene-3,4-dithiol + Dispersant
5)?




6)*Mercuric Chloride and aniline
6)brown




7)Cacotheline
7)violet




8)Dimethylglyoxime and *ferric
8)red to clear




salts




9)*Sodium Dimethylglyoxime
9)red to clear




and *ferric salts




10)Diazine green
10)violet to red




11)2-Benzyl pyridine
11)red




12)*Ammonium
12)yellow to




phosphomolybdate
deep blue




13)1,2,7-
13)orange




Trihydroxyanthroquinone




14)*Anthroquinone-1-azo-4-
14)blue-violet




dimethylaniline hydrochloride




15)*Ferric ferricyanide
15)blue




16)Ammonium sulfotellurate
16)black




17)Dithiol
17)red




18)Ammonium
18)blue




phosphomolybdate




19)Morin
19)yellow-





green





fluorescence




20)*Nitronaphthol sulfonic acid
20)blue





fluorescence




21)Mercuric chloride and aniline
21)brown




22)Oxidation products of o-
22)geen to blue-




aminophenols
geen




23)*Phosphomolybdic acid and
23)blue




ammonium acetate




24)Glyoxal bis-2-hydroxyanil
24)blue




25)*Sodium rhodizonate
25)violet


Antimony
SbBr3; SbCl3; SbF3;
1)Brilliant green
1)?


(#51)
(SbO)KC4H4O6•1⁄2H2O
2)*Brompyrogallol Red
2)?




3)*Silver diethyldithiocarbamate
3)?




4)*Rhodamine B
4)violet or blue




5)*Phosphomolybdic acid
5)blue




6)9-Methyl-2,3,7-
6)red




trihydoxyfluorone




7)*Ammonium sulfotellurate
7)black




8)*Mercuric cyanide
8)black or gray




9)*Phosphomolybdic acid
9)blue




10)9-methyl-2,3,7-trihydroxy-6-
10)red




fluorone




11)Gallein
11)violet




12)Morin
12)blue green





fluorescence





(UV)


Thallium
TlOH; TlCO2;
1)Brilliant green
1)?


(#81)
TlClO4;
2)Dithizone
2)?



TlF; TlNO3;
3)*Rhodamine B
3)?



(NH4)3Tl6•2H2O;
4)*Potassium Iodide
4)bright yellow



TlP2O7; Tl2SO4
5)Benzidene
5)blue




6)*Phosphomolybdic acid + *hydrobromic
6)blue




acid




7)*Dipycryl amine (or *sodium
7)red




salt)




8)*Ammonium sulfide
8)black-brown




9)*Sodium sulfotellurate
9)brown




10)*Oxidation to trivalent
10)blue




thallium in acid solution




11)*Sodium carbonate and
11)black-brown




ammonium sulfide




12)*Gold chloride and palladium
12)cinnamon-




chloride
brown




13)*Alkaline ferricyanide
13)blue-green




14)*Uranyl sulfate
14)fluorescence





fade




15)8-Hydroxyquinoline
15)?


Lead (#82)
Pb(C2H3O2)2•2H2O;
1)Dithizone
1)brick red



PbBr2; PzbCL2;
2)*Sodium
2)?



Pb(ClO4)2; Pb(NO3)2;
Diethyldithiocarbamate




3)4-(2-Pyridylazo)resorcinol
3)?




4)*Sodium rhodizonate
4)a)violet(neutral)





b)scarlet-





red(weak





acid




5)*Cadmium-stannous iodide + iodine
5)orange-red




6)Gallocyanine
6)violet




7)Carminic acid
7)violet




8)Benzidine
8)blue




9)Chloranilic acid
9)brown


Bismuth
Bi(NO3)2•5H2O in dil.
1)Dithizone
1)?


(#83)
HNO3;
2)*Pyrocatechol violet
2)?



Bi2(SO4)3 in H2SO4.
3)*Pyrocatechol violet + Cetyltromethylammonium
3)?




bromide




4)*Thiourea
4)?




5)*Xylenol Drange
5)?




6)Cinchonine and *potassium
6)orange-red




iodide




7)*Alklali stannate and *lead
7)free




salts
lead(grey)




8)*Potassium chromium
8)brick red




thiocyanate




9)*Alkali stannite + *lead
9)orange or




chloride
black-brown




10)*Potassium manganese (II)
10)black




cyanide




11)Quinoline and *potassium
11)orange-red




iodide




12)*Thioacetamide
12)yellow-





green









Table 5 represents non-metals, corresponding water soluble salts, resultant inorganic precipitants, and color of the precipitant.









TABLE 5







Color of


Non-Metals
Water Soluble Salts
Product




















PRECIPITANTS.





Inorganic precipitants




*water soluble


Boron (#5)
H2BO3; Borates,
1)*Azomethine H
1)?



Boranes and
2)*Carminic acid
2)red to blue



Borohydrides
3)*Curcumin
3)blue to





greenish black




4)*Methylene Blue
4)?




5)*Alizarin S
5)yellowish red





to red




6)Purpurin(*hot)
6)orange to





wine red




7)Quinalizarin
7)violet to blue




8)Chromotrope 2B
8)greenish-blue




9)Benzoin
9)yellow-green





fluorescence




10)*Triphenyltetrazolium
10)red (boranes




chloride
and





borohydrides in





soln.)




TESTS FOR AMMONIA


Nitrogen (as
NH4OH;
1)*Phenol + *Sodium
1)?


Ammonia)
NH4C2H3O2;
Hypochlorite


(#7)
NH4H2AsO4;
2)*pNitrobenzenediazonium
2)red



NH4AsO4;
chloride



NHBr;
3)*Manganese sulfate-*Hydrogen
3)blue



(NH4)2CO3•2H2O;
peroxide + Benzidene



NH4HCO3; NH4Cl;
4)Litmus
4)blue



NH4ClO4;
5)*Manganese sulfate and *silver
5)black



(NH4)2CrO4;
nitrate



NH4CNO; NH4CN;
6)8-Hydroxyquinoline and *zinc
6)light yellow



(NH4)2Cr2O7; NH4F;
chloride



NH4I; NH4IO3;
7)Formation of indophenol blue
7)blue



(NH4)6Mo7O24•H20;
8)*Silver nitrate and tannin
8)metallic silver



NH4NO2; NH4NO3;
9)Nessler's reagent
9)yellow or



(NH4)2C2O4•H2O;

orange-red



NH4MnO4;
10)Formation of manganese
10)blue (with



(NH4)2S2O8;
dioxide
bezidene or



(NH4)2PtCl4;

tetrabase)



(NH4)2HPO4;
11)All other tests are for the
11)See



(NH4)3PO4;
various water soluble salts of the
individual



NH4H2PO4;
particular elements involved as
elements for the



(NH4)2SO4; (NH4)2S;
indicated in the other tables for
water soluble



(NH4)2S2O5;
that element.
salts and the



(NH4)2SO3•H2O;

ligands and



(NH4)2S2O3;

colors



(NH4)2SeO4;

produced.



NH4SCN;



(NH4)2C4H4O6


Phosphorous
HPO3; H3PO2;
1)Rhodamine B + *Molybdate + Benzidene
1)blue


(#15)
H3PO3; H3PO4;
2)Malachite Green + *Molybdate
2)?



H4P2O7; PH4I; PH4Cl.
3)*Ammonium molybdate and
3)blue




benzidine




4)o-Dianisidine molybdate and
4)brown to blue




*hydrazine




5)Qinolinium molybdate
5)yellow


Arsenic
AsO3; AsBr3; AsCl3;
1)*Silverdiethyldithiocarbamate;
1)?


(#33)
AsI3; AsOCl;
2)*Stannous chloride;
2)brownish-



H2AsO4•1⁄2H2O;

black



H2AsO7.
3)*Silver nitrate + *HCl + Zn
3)a)lemon





yellow





b)blue to





blue-red




4)Kairine(*with HCl) - *ferric
4)red-brown




chloride




5)*Ammonium sulfotellurate
5)black




6)Gold chloride
6)metallic gold


Selenium
SeO2; H2SeO3;
1)3,3′-Diaminobenzene
1)?


(#34)
H2SeO4
2)*Hydriodic acid
2)red-brown




3)Pyrrole
3)blue




4)Diphenylhydrazine
4)red-violet




5)*Thiourea (solid)
5)red




6)*Ferrous sulfate
6)reduction to





Se




7)*Thiourea (10% solution)
7)red-blue





fluorescence




8)1,8-Naphthalenediamine
8)brown




9)4-Dimethylamino-1,2-
9)red




phenylenediamine




10)4-Methylthio-1,2-
10)blue




phenylenediamine


Tellurium
H6TeO6
1)*Hypophosphorous acid
1)black or grey


(#62)

2)* Alkali Stannite
2)black or grey




3)Formation of complex cupric
3)yellow




(III) tellurate




4)*Ferrous sulfate and
4)reduction to




*phosphoric acid
Te




5)*Ammonium polysulfide and
5)black




sodium sulfite









Table 6 represents halogens, corresponding water soluble salts, resultant inorganic precipitants, color of the precipitant as well as a references.










TABLE 6







PRECIPITANTS.





Inorganic precipitants
Color of


Halogens
Water Soluble Salts
*water soluble
Product







Fluorine (#9)
Fluorides;
1)Alizarin Fluorine Blue + Lanthanum
1)red to blue



Silicofluoride; Boron
(III) ion



fluoride, etc,
2)Zirconium alizarinate
2)red-violet




3)Zirconium azoarsenate
3)brown to red




4)Thymol blue and zirconium salt
4)blue




5)Xylenol orange and zircomium
5)orange




salt


Chlorine (#17)
HClO3•7H2O;
1)N,N-Dethyl-1.4-
1)?



HClO4; Cl2O; ClO2;
phenylenediamine



and most chlorate
2)*Manganese sulfate and
2)violet



compounds
*Phosphoric acid



Hypochlorites are
3)*Triphenylselenonium salts
3)white



tested with 4), 5)&6).,
4)*Safranin(C.I. Basic Red)
4)violet



Chlorites use 7)
5)*Thallous hydroxide
5)brown



Chlorides use 8)
6)ZnCl2 + KI + starch
6)blue




7)Nickel hydroxide
7)black




8)Formation of chromyl chloride + diphenylcarbizide
8)violet


Bromine
HBrO3; and most
1)*Fluorescein
1)pink to red


(#35)
bromate compounds,
2)Phenol Red
2)?



Hypobromites are
3)*Manganese sulfate and
3)red



tested with 6), 7), 8).
*Sulfuric acid + Benzidene



Bromides use 11)
4)*Fuchsin
4)violet




5)*Permolybdate and alpha-
5)orange-red




napthaflavone




6)*Safranin(C.I. Basic Red)
6)violet




7)*Thallous hydroxide
7)brown




8)*ZnCl2 + *KBr + fluorescein
8)red




9)*Sulfanilic acid
9)violet to





brown




10)*Phosphomolybdic acid + *sulfosalicylic
10)blue or




acid
green




11)*KMnO4 + *CuSO4 + *iodide + starch
11)blue


Iodine (#35)
H5IO6; I2O5; and
1)*Hypophosphorous acid + starch
1)blue-blue



many iodide and

black



iodate compounds,
2)*Potassium thiocyanate + starch
2)blue-blue



KI, KIO3 etc.

black



Iodates use
3)*Pyrogallol
3)pink to red



1), 2). 3), 16)
4)Neocuproine *copper(II)
4)?



Iodides use
5)*Starch + *KI
5)blue-blue



13), 14), 15)and othe

black for free



tests as adapted

Iodine




6)*Manganeses sulfate and
6)violet




*Phosphorous acid + diphenylcarbizide




7)*Manganese salt and tetrabase
7)blue




8)*Fluorescein
8)red-yellow




9))*Fluorescein + *peroxides
9)red-yellow




10)*Starch + *peroxides
10)blue-blue-





black




11)*Thallous hydroxide
11)brown




12)*ZnCl2 + Thiodene
12)blue




13)*Palladium chloride
13)black-brown




14)*Potassium nitrite + starch
14)blue




15)*AgNO3
15)yellow




16)p-Aminophenol (for iodates)
16)blue-violet









Table 7 represents other reactants, corresponding water soluble salts, resultant inorganic precipitants, and color of the precipitant.










TABLE 7







PRECIPITANTS.





Inorganic precipitants
Color of


Metals
Water Soluble Salts
*water soluble
Product




















Luminol
Hemin
1)
*Peroxides
1)
Intense blue







luminescence


Amino Acids
Glycocoll, alanine, 1-
1)
*Sodium hypochlorite
1)
red



asparginic acid,

(saturated solution) + Fuchsin-



tyrosine, diiodotyrosine,

sulfurous acid



d-arginine, etc,


Proteins
Egg albumin,
1)
*Tetrabromonaphthalein ethyl
1)
yellow to



hemoglobin, serum

ester (potassium salt)

blue



albumin, casein, any



other native protein,



etc.


Nitrogen (#7)
A) Nitrate
A)
1) Brucine
A)
1) ?





2) Chromotropic acid

2) ?





3) Sulfanilamide + N-(1-

3) ?





Naphthyl)ethylenediamine





dihydrochloride



B) Nitrite
B)
1) Sulfanilamide + N-(1-
B)
1) ?





Naphthyl)ethylenediamine





dihydrochloride





2) Sulfanilic acid + 1-

2) ?





Naphthylamine



C) Nitric Acid
C)
1) *Ferrous sulfate (soliD) and
C)
1) brown





*sulfuric acid

ring around







crystal





2) Diphenylamine or

2) blue





diphenylbenzidene





3) Brucine

3) red




D)
1) Alpha-naphthylamine and
D)
1) red





sulfanilic acid





2) 1,8-Naphthalenediamie

2) orange-red





3) *Iodide and starch

3) blue





4) Chrysean

4) red to dark







brown





5) Benzidene

5) yellow to







brown





6) *Ferrous sulfate and

6) brown ring





*acetic acid

around crystal


Sulfur (#16) 
A) Persulfuric acid
A)
Benzidene
A)
blue



B) Sulfuric acid
B)
Barium rhodizonate
B)
red-brown



  (soluble sulfate)



C) Sulfuric acid (free)
C)
*Glucose
C)
charring



D) Sulfurous acid
D)
1) *Sodium nitroprusside
D)
1) red



  Sulfates A)

2) *Zinc nitroprusside

2) pink to



  Sulfides D)



dark red



  Sulfites D)

3) Decolorization of malachite

3) decolrization





green





4) 2-Benzylpyridene

4) red









Many other reactions as shown in “Qualitative Analysis By Spot Tests”, Feigl (1946 ed.) and newer can also be used. All water soluble substances, whether Inorganic, Organic, Proteinaceous, Enzymatic, etc. Precipitants include water soluble reagents or reagents that can be made water soluble by alkali or acid treatment and that individually or together with another water soluble or dispersible reagent can cause a color to form either as a precipitate or as a color on a filter paper.
Fluorescent indicators are substances which show definite changes in fluorescence with change in pH. A long wavelength ultraviolet lamp is used to show the fluorescence. Referring to table 8 there are shown representative fluorescent indicators which can be used with the present invention.










TABLE 8







Color change



Name
pH range
acid to base
Indicator solution







Benzoflavine
−0.3 to 1.7  
Yellow to green
1


3,6-Dihydroxyphthalimide
  0 to 2.4
Blue to green
1



6.0 to 8.0
Green to




yellow/green


Eosin (tetrabromofluorescein)
  0 to 3.0
Non-fl to green
4, 1%


4-Ethoxyacridone
1.2 to 3.2
Green to blue
1


3,6-Tetramethyldiaminoxanthone
1.2 to 3.4
Green to blue
1


Esculin
1.5 to 2.0
Weak blue to




strong blue


Anthranilic acid
1.5 to 3.0
non-fl to light
2 (50% ethanol)




blue



4.5 to 6.0
Light blue to dark




blue



12.5 to 14  
Dark blue to non-




fl


3-Amino-1-naphthoic acid
1.5 to 3.0
Non-fl to green
2 (as sulfate in 50%





ethanol)



4.0 to 6.0
Green to blue



11.6 to 13.0
Blur to non-fl


1-Naphthylamino-6-sulfonamide
1.9 to 3.9
Non-fl to green
3


(also the 1-, 7-)
 9.6 to 13.0
Green to non-fl


2-Naphthylamino-6-sulfonamide
7.9 to 3.9
Non-fl to dark
3




blue


(also the 2-, 8-)
 9.6 to 13.0
Dark blue to non-




fl


1-Naphthylamino-5-sulfonamide
2.0 to 4.0
Non-fl to
3




yellow/orange



 9.5 to 13.0
Yellow/orange to




non-fl


1-Naphothoic acid
2.5 to 3.5
Non-fl to blue
4


Salicyclic acid
2.5 to 4.0
Non-fl to dark
4 (0.5%)




blue


Phloxin BA extra
2.5 to 4.0
Non-fl to dark
2


(tetrachlorotetrabromofluorescein)

blue


Erythrosin B
2.5 to 4.0
Non-fl to light
4 (0.2%)


(tetraiodofluorescein)

green


2-Naphthylamine
2.8 to 4.4
Non-fl to violet
1


Magdala red
3.0 to 4.0
Non-fl to purple


p-
3.0 to 4.0
Non-fl to light
3


Aminophenylbenzenesulfonamide

blue


2-Hydroxy-3-naphthoic acid
3.0 to 6.8
Blue to green
4 (0.1%)


Chromotropic acid
3.1 to 4.4
Non-fl to light
4 (5%)




blue


1-Naphthionic acid
3 to 4
Non-fl to blue
4



10 to 12
Blue to yellow-




green


1-Naphthylamine
3.4 to 4.8
Non-fl to blue
1


5-Aminosalicylic acid
3.1 to 4.4
Non-fl to light
1 (0.2% fresh)




green


Quinine
3.0 to 5.0
Blue to weak
1 (0.1%)




violet



 9.5 to 10.0
Weak violet to




non-fl


o-Methoxybenzaldehyde
3.1 to 4.4
Non-fl to green
4 (0.2%)


o-Phenylenediamine
3.1 to 4.4
Green to non-fl
5


p-Phenylenediamine
3.1 to 4.4
Non-fl to
5




orange/yellow


Morin(2′,4′,3,5,7-
3.1 to 4.4
Non-fl to green
6 (0.2%)


pentahydroxyflavone
  8 to 9.8
Green to




yellow/green


Thioflavine S
3.1 to 4.4
Dark blue to light
6 (0.2%)




blue


Fluorescein
4.0 to 4.5
Pink/green to
4 (1%)




green


Dichlorofluorescein
4.0 to 6.6
Blue green to
1




green


β-Methylescletin
4.0 to 6.2
Non-fl to blue
1



 9.0 to 10.0
Blue to light




green


Quininic acid
4.0 to 5.0
Yellow to blue
6 (satd)


β-Naphthoquinoline
4.4 to 6.3
Blue to non-fl
3


Resorufin(7-oxyphenoxazone)
4.4 to 6.4
Yellow to orange


Acridine
5.2 to 6.6
Green to violet
2


3,6-Dihydroxyxanthone
5.4 to 7.6
Non-fl to
1




blue/violet


5,7-Dihydroxy-4-methylcoumarin
5.5 to 5.8
Light blue to dark




blue


3,6-Dihydroxyphthalic acid
5.8 to 8.2
Blue to green
1


dinitrile


1,4-Dihydroxybenzenedisulfonic
6 to 7
Non-fl to light
4 (0.1%)


acid

blue


Luminol
6 to 7
Non-fl to blue


2-Naphthol-6-sulfonic acid
5-7 to 8-9
Non-fl to blue
4


Quinoline
6.2 to 7.2
Blue to Non-fl
6 (satd)


1-Naphthol-5-solfonic acid
6.5 to 7.5
Non-fl to green
6 (satd)


Umbelliferone
6.5 to 8.0
Non-fl to blue


Magnesium-8-hydroxyquinolinate
6.5 to 7.5
Non-fl to yellow
6 (0.1% in 0.01 M HCl)


Orcinaurie
6.5 to 8.0
Non-fl to green
6 (0.03%)


Diazo brilliant yellow
6.5 to 7.5
Non-fl to blue


Coumaric acid
7.2 to 9.0
Non-fl to green
1


β-Methylumbelliferone
>7.0  
Non-fl to blue
2 (0.3%)


Harmine
7.2 to 8.9
Blue to yellow


2-Naphthol-6,8-disulfonic acid
7.5 to 9.1
Blue to light blue
4


Salicylaldehyde semicarbazone
7.6 to 8.0
Yellow to blue
2


1-Naphthol-2-sulfonic acid
8.0 to 9.0
Dark blue to light
4




blue


Salicylaldehyde acetylhydrazone
8.3
Non-fl to
2




green/blue


Salicylaldehyde
8.4
Non-fl to
2


thiosemicarbazone

blue/green


1-Naphthol-4-solfonic acid
8.2
Dark blue to the
4




light blue


Naphthol AS
 8.2 to 10.3
Non-fl to
4




yellow/green


2-Naphthol
8.5 to 9.5
Non-fl blue
2


Acridine orange
 8.4 to 10.4
Non-fl to




yellow/green


Orcinsulfonephthalein
 8.6 to 10.0
Non-fl to yellow


2-Naphthol-3,6-disulfonic acid
9.0 to 9.5
Dark blue to light
4




blue


Ethoxyphenylnaphthostilbazonium
 9 to 11
Green to non-fl
1


chloride


o-Hydroxyphenylbenzothiazole
9.3
Non-fl to blue
2




green


o-Hydrozyphenylbenzoxazole
9.3
Non-fl to
2




blue/violet


o-Hydroxyphenylbenzimidazole
9.9
Non-fl to
2




blue/violet


Coumarin
 9.5 to 10.5
Non-fl to light




green


6,7-Dimethoxyisoquinoline-1-
 935 to 11.0
Yellow to blue
0.1% in


carboxylic acid


clycerine/ethanol/water





in 2:2:18 ratio


1-Naphthylamino-4-sulfonamide
 9.5 to 13.0
dark blue to
3




white/blue









Some of the common acid-base indicators which can be used with the present invention are shown in table 9 with the corresponding pH range.










TABLE 9









pH range
Color











Indicator
Minimum
Maximum
Acid
Alkaline














Brilliant cresyl blue
0.0
1.0
red-orange
blue


Methyl violet
0.0
1.6
yellow
blue


Crystal violet
0.0
1.8
yellow
blue


Ethyl violet
0.0
2.4
yellow
blue


Methyl violet 6B
0.1
1.5
yellow
blue


Cresyl red
0.2
1.8
red
yellow


2-(p-Dimethylaminophenylazo)
0.2
1.8
yellow
blue


pyridine


Malachite green
0.2
1.8
yellow
blue-green


Methyl green
0.2
1.8
yellow
blue


Cresol red (o-
1.0
2.0
red
yellow


Cresolsulfonephthalein)


Quinaldine red
1.0
2.2
colorless
red


p-Methyl red
1.0
3.0
red
yellow


Metanil yello
1.2
2.3
red
yellow


Pentamethoxy red
1.2
2.3
red-violet
colorless


Metanil yellow
1.2
2.4
red
yellow


p-Phenylazodiphenylamine
1.2
2.6
red
yellow


Thymol blue
1.2
2.8
red
yellow


(Thymolsulfonephthalein)


m-Cresol purple
1.2
2.8
red
yellow


p-Xylenol blue
1.2
2.8
red
yellow


Benzopurpurin 4B
1.2
3.8
violet
red


Tropeolin OO
1.3
3.2
red
yellow


Orange IV
1.4
2.8
red
yellow


4-o-Tolylazo-o-toluidine
1.4
2.8
orange
yellow


Methyl violet 6B
1.5
3.2
blue
violet


Phloxine B
2.1
4.1
colorless
pink


Erythrosine, disodium salt
2.2
3.6
orange
red


Benxopupurine 4B
2.2
4.2
violet
red


N,N-dimethyl-p-(m-tolylazo)
2.6
4.8
red
yellow


aniline


2,4-Dinitrophenol
2.8
4.0
colorless
yellow


N,N-Dimethyl-p-
2.8
4.4
red
yellow


phenylazoaniline


Methyl yellow
2.9
4.0
red
yellow


Bromophenol blue
3.0
4.6
yellow
blue-violet


Tetrabromophenol blue
3.0
4.6
yellow
blue


Direct purple
3.0
4.6
blue-purple
red


Congo red
3.1
4.9
blue
red


Methyl orange
3.1
4.4
red
yellow


Bromochlorophenol blue
3.2
4.8
yellow
blue


Ethyl orange
3.4
4.8
red
yellow


p-Ethoxychrysoidine
3.5
5.5
red
yellow


Alizarin sodium sulfonate
3.7
5.2
yellow
violet


α-Naphthyl red
3.7
5.7
red
yellow


Bromocresol green
3.8
5.4
yellow
blue


Resazurin
3.8
6.4
orange
violet


Bromophenol green
4.0
5.6
yellow
blue


2,5-Dinitrophenol
4.0
5.8
colorless
yellow


Methyl red
4.2
6.2
red
yellow


2-(p-Dimethylaminophenylazo)
4.4
5.6
red
yellow


pyridine


Lacmoid
4.4
6.2
red
blue


Azolitmin
4.5
8.3
red
blue


Litmus
4.5
8.3
red
blue


Alizarin red S
4.6
6.0
yellow
red


Chlorophenol red
4.8
6.4
yellow
red


Cochineal
4.8
6.2
red
violet


Propyl red
4.8
6.6
red
yellow


Hematoxylin
5.0
6.0
red
blue


Bromocresol purple
5.2
6.8
yellow
violet


Bromophenol red
5.2
7.0
yellow
red


Chlorophenol red
5.4
6.8
yellow
red


p-Nirophenol
5.6
6.6
colorless
yellow


Alizarin
5.6
7.2
yellow
red


Bromothymol blue
6.0
7.6
yellow
blue


Indo-oxine
6.0
8.0
red
blue


Bromophenol blue
6.2
7.6
yellow
blue


m-Dinitrobenzoylene urea
6.4
8.0
colorless
yellow


Phenol red
6.4
8.0
yellow
red


(Phenolsulfonephthalein)


Rosolic acid
6.4
8.0
yellow
red


Brilliant yellow
6.6
7.9
yellow
orange


Quinoline blue
6.6
8.6
colorless
blue


Neutral red
6.8
830
red
orange


Phenol red
6.8
8.4
yellow
yellow


m-Nitrophenol
6.8
8.6
colorless
yellow


Cresol red (o-
7.0
8.8
yellow
red


Cresolsulfonephthalein)


α-Naphtholphthalein
7.3
8.8
yellow
blue


Curcumin
7.4
8.6
yellow
red


m-Cresol purple (m-
7.4
9.0
yellow
violet


Cresolsulfonephthalein)


Tropeolin OOO
7.6
8.9
yellow
rose-red


2,6-
7.8
9.4
yellow
red


Divanillydenecyclohexanone


Thymol blue
8.0
9.6
yellow
purple


(Thymolsulfonephthalein)


p-Xylenol blue
8.0
9.6
yellow
blue


Turmeric
8.0
10.0
yellow
orange


Phenolphthalein
8.0
10.0
colorless
red


o-Cresolphthalein
8.2
9.8
colorless
red


p-Naphtholphthalein
8.2
10.0
colorless
pink


Ethyl bis(2,4-
8.4
9.6
colorless
blue


dimethylphenylacetate)


Ethyl bis(2,4-dimtrophenyl
8.4
9.6
colorless
blue


acetate)


α-Naphtholbenzein
8.5
9.8
yellow
green


Thymolphthalein
9.4
10.6
colorless
blue


Nile blue A
10.0
11.0
blue
purple


Alizarin yellow CG
10.0
12.0
yellow
lilac


Alizarin yellow R
10.2
12.0
yellow
orange red


Salicyl yellow
10.0
12.0
yellow
orange-brown


Diazo violet
10.1
12.0
yellow
violet


Nile blue
10.1
11.1
blue
red


Curcumin
10.2
11.8
yellow
red


Malchite green gydrochloride
10.2
12.5
green-blue
colorless


Methyl blue
10.6
13.4
blue
pale violet


Brilliant cresyl blue
10.8
12.0
blue
yellow


Alizarin
11.0
12.4
red
purple


Nitramine
11.0
13.0
colorless
orange-brown


Poirier's blue
11.0
13.0
blue
violet-pink


Tropeolin O
11.0
13.0
yellow
orange


Indigo carmine
11.4
13.0
blue
yellow


Sodium indigosulfonate
11.4
13.0
blue
yellow


Orange G
11.5
14.0
yellow
pink


2,4,6-Trinitrotoluene
11.7
12.8
colorless
orange


1,3,5-Trinitrobenzene
12.0
14.0
colorless
orange


2,4,6 Trinitrobenzoic acid
12.0
13.4
blue
violet-pink


Clayton yellow
12.2
13.2
yellow
amber









Some of the oxidation-reduction indicators which can be used with the present invention are shown in table 10.











TABLE 10






Reduction
Potential
Suitable




(30° C.) in
Volts at
pH
Color Change


Name
pH = 0
pH = 7
range
Upon Oxidation



















Bis(5-bromo-1,10-phenanthroline)
1.41*


Red to faint blue


ruthenium(II) dinitrate


Tris(5-nitro-1,10-phenanthroline)
1.25*


Red to faint blue


iron(II) sulfate


Iron(II)-2,2′,2′′-tripyridine sulfate
1.25*


Pink to faint blue


Tris(4,7-diphenyl01,10-
1.13 (4.6 M


Red to faint blue


phenanthroline)
H2SO4)*


iron(II) disulfate
0.87 (1.0 M



H2SO4)*


o,m1-Diphenylaminedicarboxylic
1.12


Colorless to blue


acid



violet


Setopaline
1.06


Yellow to orange



(trans)


p-Nitrodiphenylamine
1.06


Colorless to violet


Tris(1,10-Phenanthroline)-iron(II)
1.06 (1.00 M


Red to faint blue


sulfate
H2SO4)*



1.00 (3.0 M



H2SO4)*



0.89 (6.0 M



H2SO4)*


Setoglaucine O
1.01


Yellow-green to



(trans)


yellow red


Xylene cyanole FF
1.00


Yellow-green to



(trans)


pink


Erioglaucine A
1.00


Green yellow to



(trans)


bluish red


Eriogreen
0.99


Green yellow to



(trans)


orange


Tris(2,2′-bipyridine)-iron(II)
0.97*


Red to faint blue


hydrochloride


2-Carboxydiphenylamine[N-
0.94


Colorless to pink


phenyl-anthranilic acid]


Benxidine dihydrochloride
0.92


Colorless to blue


o-Toluidine
0.87


Colorless to blue


Bis(1,10-phenanthroline)-
0.859 (0.1 M


Green to pink


osmium(II)
H2SO4)


perchlorate


Diphenylamine-4-sulfonate (Na
0.85


Colorless to violet


salt)


3,3′-Dimethoxybenzidine
0.85


Colorless to red


dihydrochloride


[o-dianisidine]


Ferrocyphen
0.81


Yellow to violet


4′-Ethoxy-2,4-diaminoazobenzene
0.76


Red to pale yellow


N,N-Diphenylbenzidine
0.76


Colorless to violet


[o-dianisidine]



Colorless to red


Ferrocyphen
0.81


Yellow to violet


4′-Ethoxy-2,4-diaminoazobenzene
0.76


Red to pale yellow


N,N-Diphenylbenzidine
0.76


Colorless to violet


Diphenylamine
0.76


Colorless to violet


N,N-Dimethyl-p-
0.76


Colorless to red


phenylenediamine


Variamine blue B hydrochloride
0.712
0.310
1.5-6.3 
Colorless to blue


N-Phenyl-1,2,4-benzenetriamine
0.70


Colorless to red


Bindschedler's green
0.680
0.224
 2-935


2,6-Dichloroindophenol (Na salt)
0.668
0.217
6.3-11.4
Colorless to blue


2,6-Dibromophenolindophenol
0.668
0.216
7.0-12.3
Colorless to blue


Brilliant cresyl blue [3-amino-9-
0.583
0.047
0-11
Colorless to blue


dimethyl-amino-10-


methylphenoxyazine chloride]


Iron (II)-tetrapyridine chloride
0.59


Red to faint blue


Thionine [Lauth's violet]
0.563
0.064
1-13
Colorless to violet


Starch (soluble potato, I3 present)
0.54


Colorless to blue


Gallocyanine (25° C.)

0.021

Colorless to violet


Methylene blue
0.532
0.011
1-13
Colorless to blue


Nile blue A
0.406
−0.199
1.4-12.3
Colorless to blue


[aminonaphthodiethylamino-


phenoxazine sulfate]


Indigo-5,5′,7,7′-tetrasulfonic acid
0.365
−0.046
<9
Colorless to blue


(Na salt)


Indigo-5,5′,7-trisulfonic acid (Na
0.332
−0.081
<9
Colorless to blue


salt)


Indigo-5,5′-disulfonic acid (Na
0.291
−0.125
<9
Colorless to blue


salt)


Phenosafranine
0.280
−0.252
1-11
Colorless to violet


Indigo-5-monosulfonic acid (Na
03262
−0.157
<9
Colorless to blue


salt)


Safranine T
0324
−03289
1-12
Colorless to violet


Bis(dimethylglyoximato)-iron(II)
0.155

6-10
Red to colorless


chloride


Induline scarlet
0.047
−0.299
 3-8.6
Colorless to red


Neutral red

−0.323
2-11
Colorless to red-






violet









FIG. 1 is a perspective view of a preferred embodiment of the indicator of the present invention. For exemplary purposes only, the embodiment of a freeze-thaw indicator will be discussed; however, other embodiments are equally available for use. The device 10 comprises a housing 20 and a capsule 30. Housing 20 defines an interior 22. Interior 22 is bounded by a first surface 24 and a second surface 27 (see FIG. 4). A first reactant 26 is provided within housing 20. Reactant 26 may be located within housing 20 in various ways. For example, reactant 26 can be applied directly to surface 24 or reactant 26 may be applied to a piece of material, such as filter paper, and the material placed inside housing 20. In addition to filter paper, other carriers may also be used with the present invention.
Capsule 30 is located within housing 20. Capsule 30 contains a second reactant 32. Capsule 30 also contains a liquid 34. Liquid 34 is chosen such that it expands upon freezing. A preferred form of liquid 34 is an aqueous solution. Capsule 30 is designed such that it will fracture when liquid 34 freezes. After fracture, reactant 32 can escape capsule 30 to mix with reactant 26. This will not occur, however, while device 10 is in a frozen condition. When device 10 enters a thawed condition, liquid 34 melts/thaws, releasing reactant 32. Reactant 32 then mixes with reactant 26 to form a pigment, indicating that device 10 has made the transition from a frozen condition to a thawed condition. Note that the rigidity of housing 20 can function as a means to protect against crushing of capsule 30.
FIG. 2 is a top view of the freeze-thaw indicator of FIG. 1 indicating a safe condition. Either device 10 has never been frozen or has been frozen and not thawed. One can view first surface 24 through second surface 27. In this condition, surface 24 has a first color 40.
FIG. 3 is a top view of the freeze-thaw indicator of FIG. 1 indicating a transition from a frozen condition to a thawed condition. Device 10 has been frozen and capsule 30 has been fractured. Reactants 32 and 26 have combined to form a pigment. This pigment causes surface 24 to become brilliantly colored to a second color 42, color 42 being different than color 40. Alternatively, if reactant 26 were placed on a piece of material, the material and not necessarily surface 24 will become colored upon mixture of reactants 26, 32. Thus a person can easily determine whether device 10—and therefore any item to which device 10 has been attached—has previously been frozen and thawed.
FIG. 4 is a sectional view of the freeze-thaw indicator of FIG. 1 taken along line 4-4. It is seen that in a preferred embodiment, housing 20 can have two layers 46, 48. At least a portion of layer 46 is transparent, allowing one to view inside housing 20. At least a portion of layer 48 contains an adhesive, allowing device 10 to be coupled to an item to be monitored. One preferred material for housing 20 is foam-board. This material is readily available and inexpensive. Another preferred material for housing 20 is cork. Cork is also readily available and is less crushable than foam-board, which facilitates the manufacturing process. However, housing 20 can be made of any suitable material.
For illustrative purposes only, a preferred manufacturing process will be discussed using cork as the material of housing 20. Device 10 may be manufactured by first providing an amount of cork, preferably in the form of a roll. The cork can then be machined in known fashion to form interior 22. Several interiors 22 can be formed simultaneously. Preferably, the cork has already been treated with an adhesive on each side. Alternatively, adhesive can be applied subsequent to machining interiors 22 in the cork. Once interior 22 has been formed, first reactant 26 can be added. Reactant 26 may be applied to a piece of material, such as paper, and that material placed within interior 22. Capsule 30, which has been manufactured previously and has second reactant 32 and liquid 34 located therein, is then added to interior 22. Transparent layer 46 and adhesive layer 48 can then be added on either side of housing 20, creating a closed volume for interior 22. A preferred method of attachment is lamination. The completed device 10 can then be coupled to an item to be monitored. It should be noted that the order of the steps of the above process can be altered. For example, transparent layer 46 or adhesive layer 48 can be applied to housing 20 prior to adding first reactant 26. In this manner, first reactant 26 can be applied directly to transparent layer 46 or adhesive layer 48.
The reactants discussed above cooperate to form a pigment upon mixing. Use of a pigment as an indicator is better than use of a dye for several reasons. First, pigments are insoluble in water and are solid particles rather than solutions. Dyes completely dissolve in water and are, therefore, solutions. Thus, a smaller amount of each reactant is needed to create a reliable indicator with a pigment than with a dye. This allows an indicator using pigment reactants to use fewer capsules and be smaller than an indicator using dye reactants. As few as a single capsule may be used with the present invention. A smaller indicator may be attached to more items—such as an individual vaccination vial—than are possible with a larger indicator.
Secondly, it is possible to get more “color” into pigments than into dyes. Therefore, pigmented colors tend to be more vibrant and brilliant than dye-based colors. A more brilliant, vibrant color is desirable with a changed condition indicator to increase readability and decrease the likelihood of an erroneous reading. Thus, an indicator with pigment reactants is more reliable than one with dye reactants.
Thirdly, pigment reactants are less likely to react with anything other than the complementary reactant. Thus, an indicator with pigment reactants is more reliable than one with dye reactants.
Finally, the molecules in a dye are spread out and are therefore prone to fading. The molecules in a pigment are spaced closer together and are therefore less prone to fading. If the color in an activated indicator (that is, an indicator that has been cooled below and then heated above the threshold temperature) fades, one might erroneously be lead to believe that the item to which the indicator is attached has been continuously maintained below the threshold temperature. As discussed above, this could lead to grave consequences. Thus, an indicator with pigment reactants is more reliable than one with dye reactants.
Exemplary reactants include water soluble sodium dimethylglyoxime and any water soluble nickel salt, such as nickel chloride. The sodium dimethylglyoxime could be inside the capsule and the nickel salt outside or vice versa. These reactants combine to form a brilliant scarlet, solid, colloidal crystal. These reactants are highly specific and are unlikely to form such a color with other substances. Other pigment reactants may also be used with the indicator of the present invention and other pigment colors may be produced upon a freeze-thaw transition. Once the reactants combine to form a pigment, the pigment remains even if the device is subsequently refrozen.
The capsules that are used with the present invention were manufactured using the equipment described in U.S. Pat. No. 3,389,194, the disclosure of which is incorporated herein in its entirety. Three capsule shell materials were developed. The first shell composition was made of paraffin wax. The second shell composition was made of a paraffin wax blended with a hydrocarbon resin. The third shell composition was made of a paraffin wax blended with a hydrocarbon resin and a polyethylene. Piccolyte S-115 is a preferred hydrocarbon resin. All the capsules were prepared with 5% dimethylglyoxime as a solute in water and the fill to shell ratio ranged from 50/50 to 60/40. Upon testing, the third shell composition was found to result in more completely cracked capsules upon freezing.
A preferred composition comprises 40% paraffin wax, 50% piccolyte S-115 (a hydrocarbon resin), and 10% polyethylene, with a 60% fill to 40% shell ratio. This composition was found to result in proper brittleness at freezing so that assurance of capsule cracking was increased.
The capsule composition may also be altered to provide a high temperature indicator. For example, pure paraffin wax melts at approximately 95° F. Thus, if the capsules are formed of pure paraffin wax, they will melt at approximately 95° F., allowing the reactants to mix and causing a color change. Additives, such as polyethylene, may be added to the paraffin to increase the melting temperature without adversely affecting brittleness. Thus, by selectively adding polyethylene to the paraffin wax and creating the capsules, they may be designed to melt at a predetermined temperature. The indicator can therefore function as a high temperature indicator. Note that this high temperature indicator embodiment may be used in conjunction with the low temperature embodiments discussed above and below, resulting in a dual indicating device.
Although the capsules were filled with a 5% solution of dimethylglyoxime and the co-reactant was located externally to the capsules, the location of the reactants could have been reversed. Also, the capsules could be loaded with a reducing agent such as a 10% solution of sodium bisulfite, or an acid solution, or a base solution and placed upon a colored matrix which when reduced, acidified or alkalinized changes from one color to another.
The threshold temperature at which the device of the present invention will indicate a changed condition may be varied by varying the composition of liquid 34. By adding and varying the composition of sodium dimethylglyoxime within liquid 34 within capsules 30, capsules 30 may be made to fracture at temperatures as low as −26° C. This allows indicator 10 to be used with items that should be maintained at a temperature below freezing, such as frozen vaccines.
Varying the composition of sodium dimethylglyoxime within liquid 34 may be accomplished by adding salt (NaCl) to water (H2O) and encapsulating the mixture within capsule 30. By controlling the amount of salt, according to the well-known Arrenhius equation, the freezing point of liquid 34 can be adjusted to freeze, and therefore fracture capsule 30, at any temperature between 0° C. and approximately −26° C. An unexpected advantage of the salt addition is that the intensity of the color change that occurs when nickel-dimethylglyoxime pigment is formed is greater than when no additional salt other than the sodium dimethylglyoxime is present in the aqueous solution 34.
Other substances, such as propylene glycol, glycerin, magnesium chloride, calcium chloride and/or other salts, may be used to lower the freezing point of liquid 34. However, sodium chloride (NaCl) is preferred because it is inexpensive and non-toxic. Additionally, while other metallic salts might adversely interfere with the reaction, sodium chloride essentially does not, and, if anything, enhances the reaction. This is probably due to the common ion (sodium or chloride or both) effect. Substances such as alcohol, acetone, propylene glycol, and glycerin are not preferred for use in altering the freezing temperature of liquid 34 since they may soften the shell of capsule 30 if a wax composition is used.
Table 11, which was taken from “Lange's Handbook of Chemistry,” Revised Tenth Edition (1966), illustrates the percent salt in an aqueous solution and the lowered freezing point resulting therefrom.












TABLE 11









% NaCl
Spec. Gravity
Freezing Point













by weight
15° C. (59° F.)
° C.
° F.
















 0
1.000
0.00
32.0



 1
1.007
−0.58
31.0



 2
1.014
−1.13
30.0



 3
1.021
−1.72
28.9



 4
1.028
−2.35
27.8



 5
1.036
−2.97
26.7



 6
1.043
−3.63
25.5



 7
1.051
−4.32
24.2



 8
1.059
−5.03
22.9



 9
1.067
−5.77
21.6



10
1.074
−6.54
20.2



11
1.082
−7.34
18.8



12
1.089
−8.17
17.3



13
1.097
−9.03
15.7



14
1.104
−9.94
14.1



15
1.112
−10.88
12.4



16
1.119
−11.90
10.6



17
1.127
−12.93
8.7



18
1.135
−14.03
6.7



19
1.143
−15.21
4.6



20
1.152
−16.46
2.4



21
1.159
−17.78
0.0



22
1.168
−19.19
−2.5



23
1.176
−20.69
−5.2



23.3 (E)
1.179
−21.13
−6.0



24
1.184
−17.0*
1.4*



25
1.193
−10.4*
13.3*



26
1.201
−2.3*
27.9*



26.3
1.203
0.0*
32.0*







*Saturation temperatures of sodium chloride dihydrate; at these temperatures NaCl2H2O separates leaving the brine of the eutectic composition (E).






Color-coding may be used to differentiate the threshold temperature of the capsules. For example, one set of capsules 30 may be made with the natural color of the standard formulation discussed above. Another set of capsules may be prepared with salt added to the liquid 34 to adjust to the required threshold temperature, these capsules 30 being dyed light blue to distinguish them. No other change to the indicators 10 is necessary, and the same manufacturing process may be used.
Alternatively, the composition of liquid 34 could be varied such that it freezes at a temperature above 0° C. Thus, exemplary threshold temperatures include below the freezing temperature, at the freezing temperature, and above the freezing temperature. It may be desirable to determine whether capsules 30 are suitable for use prior to manufacturing device 10. To do this, one can immerse capsules 30 in a solution containing a complementary reactant to that included within capsule 30. For example, if sodium dimethylglyoxime is used as the reactant within capsules 30, the solution can contain a solution of nickel chloride. A preferred solution contains 5% nickel chloride in water, to which 20% by weight glycerol is added. If a capsule is already fractured, and therefore unsuitable for use, the reactants will combine to produce a brilliant pigment when the capsule is immersed in the solution. Those capsules that do not produce a color change are suitable for use and may be separated for subsequent use in the present invention.
During testing of the present invention, it was discovered that capsules tested according to the above process retained a coating of reactant on the outer surface of the capsule 30 when removed from the solution and allowed to dry. When the capsules 30 that tested as good for use were subsequently fractured, the reactant inside capsule 30 combined with the reactant on the outer surface of capsule 30 to form a brilliant pigment. This indicates that capsules 30 may be coated with the second reactant and used in the device 10 of the present invention, without the need of separately including a reactant in the interior 22 of housing 20.
FIG. 5 is a sectional view of another preferred embodiment of the freeze-thaw indicator of the present invention. Device 110 comprises a housing 20 and a capsule 30 (described above). Housing 20 includes layers 46, 48 and defines a volume 22. Capsule 30 has a first reactant 26 and a liquid 34 included therein. Liquid 34 is chosen such that it expands upon freezing. Device 110 further comprises a piece of material 120. Material 120 may be impregnated with second reactant 32. Alternatively, reactant 32 may be topically applied to material 120. Material 120 may take any desired form, as long as it is able to host reactant 32. Preferred forms of material 120 include, but are not limited to, paper (such as filter paper) and cotton. Upon freezing and expansion of liquid 34, capsule 30 fractures. Upon subsequent melting or thawing of liquid 34, reactant 26 is released from capsule 30 such that it contacts material 120 and reactant 32. Reactants 26 and 32 cooperate to form a brilliant pigment, notifying a viewer that device 110—and therefor any item to which device 110 has been attached—has previously been cooled below and then heated above the threshold temperature.
FIG. 6 is a sectional view of another preferred embodiment of the changed condition indicator of the present invention. Device 210 comprises a capsule 30 (described above) and a blister pack 220. Blister packs 220 are known and commonly used to package, for example, over-the-counter medications. Blister pack 220 includes a cover 222 and a backing 224. Cover 222 is substantially transparent, allowing one to view inside device 210. Backing 224 includes a first surface 225. An adhesive may be applied to surface 225 to couple device 210 to an item to be monitored. A first reactant is included within capsule 30. A second reactant may be applied to a piece of material 230, which is enclosed along with capsule 30 within blister pack 220. Alternatively, the second reactant may be applied to a second surface 226 of backing 224 using, for example, an adhesive such as latex. A preferred adhesive is polyvinyl acetate latex; a preferred reactant-latex mix includes 10-20% by volume latex. Alternatively, the second reactant may be applied to the outer surface of capsule 30. With the latter two alternatives, material 230 is not required. As discussed above, when capsule 30 fractures upon freezing and subsequently thaws, the reactants combine to form a pigment, notifying an observer that the item to which device 210 is attached has experienced a changed condition.
FIG. 7 is a sectional view of another preferred embodiment of the freeze-thaw indicator of the present invention. Device 310 comprises a housing 320 and a capsule 30. Housing 320 is substantially cylindrical and has an outer surface 330. The longitudinal ends of housing 320 may be crimped or sealed in any known manner. Device 310 may be attached to an item to be monitored in known manner, such as by applying an adhesive to surface 330. The reactants are included in any manner described above. Upon a freeze-to-thaw transition, the reactants mix as described above to produce a vibrant color, allowing one to easily determine whether the item to which device 310 is attached has been previously frozen and thawed.
FIG. 8 is a sectional view of another preferred embodiment of the changed condition indicator of the present invention. The device 410 of FIG. 8 is similar to the device 310 of FIG. 7, but includes an additional housing 420. Housing 420 and housing 320 cooperate to define a volume 430. Volume 430 functions as an air space, which is an insulator. This insulation may prevent obtaining a premature indication of a thaw condition. The amount of insulation can be varied as desired by varying the relative diameters of the housings 320, 420 (which therefore will vary the size of volume 430).
A preferred method of including the second reactant for the embodiments of FIGS. 7 and 8 is to prepare a reactant-latex mix as described above. The reactant-latex mix can then be drawn into the housing 320, such as by suction. The reactant-latex mix can then be removed from housing 320, such as by draining due to gravity. A film of the mix will remain on an inner surface 340 of housing 320. During testing, it was discovered that a film formed accordingly contained enough reactant to produce a vibrant color change upon a changed condition. This process worked on a housing made of polyethylene, which is known not to be easily coated. This process also worked on a paraffin wax coating of the capsules themselves. This process is fast, inexpensive, and readily adaptable to devices of virtually any size.
By changing the reactants, the device of the present invention may also be used as a time-temperature indicator. For example, by coating the housing with a gelatin-immobilized urease (an enzyme that breaks down urea to ammonia and carbon dioxide) together with a mixture of pH indicators and filling the capsule with a urea solution, upon fracture of the capsule the reactants will mix. This will allow the urease to produce the breakdown products of urea in response to time and temperature according to the Arrenhius equation. As these products (ammonia and carbon dioxide) accumulate in response to time, temperature, or both, the pH of the coating will change. This change in pH will result in a color change based on the indicators chosen. The concentration of the urea solution can be varied in concentration to allow for various time or temperature scenarios. Note that the capsule can be fractured by either external or internal pressure. Other chemical combinations may also be used.
By providing a relatively flexible (or at least less rigid) housing 20, 220, 320, 420, a user can initiate the process by manually fracturing capsule 30. This can be done, for example, by squeezing housing 20, 220, 320, 420. The device 10, 110, 210, 310, 410 can then be attached to an item to be monitored. By doing so, an observer can determine how long the item being monitored has been in its current condition (for example, held at room temperature). Note that by providing a less rigid housing 20, 220, 320, 420, there is no need to freeze the device 10, 110, 210, 310, 410 prior to use. Device 10, 110, 210, 310, 410, when used as a time-temperature indicator, is of the same design and manufacturing as described above with respect to the changed condition indicators.
Numerous modifications and alternative embodiments of the invention will be apparent to those skilled in the art in view of the foregoing description. For example, the received signal can be delay rather than the reference sequence. Accordingly, this description is to be construed as illustrative only and is for the purpose of teaching those skilled in the art the best mode of carrying out the invention. Details of the structure may be varied substantially without departing from the spirit of the invention and the exclusive use of all modifications, which come within the scope of the appended claim, is reserved.
FIG. 9 is a perspective view of another preferred embodiment of the indicator of the present invention. Device 510 is a dual indicator that comprises a housing 20, a first reactant 26 within housing 20, a first capsule 30, (described above) and a second capsule 530 that will melt at a predetermined high temperature. Second capsule 530 contains second reactant 32 or alternatively contains a third reactant 532. After melting, second reactant 32 or third reactant 532 can escape capsule 530 to mix with first reactant 26 to produce a colored pigment.

## Claims

1. A device for indicating a transition across a threshold temperature comprising:
a housing;
a first surface, at least a portion of said first surface being of a first color;
a first reactant located on said first surface within said housing;
a capsule containing a liquid and a second reactant, said capsule being located within said housing;
wherein said liquid freezes at a first threshold temperature and expands upon freezing whereby said capsule fractures from the liquid expansion;
wherein said first and said second reactants combine on said first surface to produce a pigment of a second color upon mixing, said first and said second colors being different; and
wherein said first reactant and said second reactant are salts of a weak acid-strong base and a strong acid-weak base, respectively;
and further comprising a second capsule located within said housing and optionally a third reactant;
wherein the formulation of said second capsule comprises a component that melts at a second threshold temperature;
wherein said second capsule contains said second reactant or said optional third reactant;
wherein when said optional third reactant is present, said third and first reactants combine to produce a pigment of a third color upon mixing, said third color being different from said first color; and wherein said third reactant is a salt of a strong acid weak base.

2. A device for indicating a transition across a threshold temperature comprising:
a housing;
a first surface, at least a portion of said first surface being of a first color;
a first reactant located on said first surface within said housing;
a capsule containing a liquid and a second reactant, said capsule being located within said housing;
wherein said liquid freezes at a first threshold temperature and expands upon freezing whereby said capsule fractures from the liquid expansion;
wherein said first and said second reactants combine on said first surface to produce a pigment of a second color upon mixing, said first and said second colors being different; and
wherein said first reactant and said second reactant are salts of a strong acid-weak base and a weak acid-strong base, respectively;
and further comprising a second capsule located within said housing and optionally a third reactant;
wherein the formulation of said second capsule comprises a component that melts at a designated second threshold temperature;
wherein said second capsule contains said second reactant or said optional third reactant;
wherein when said optional third reactant is present, said third and first reactants combine to produce a pigment of a third color upon mixing, said third color being different from said first color; and wherein said third reactant is a salt of a weak acid-strong base.

3. A device for indicating a transition across a threshold temperature comprising:
a housing;
a first surface, at least a portion of said first surface being of a first color;
a first reactant located on said first surface within said housing;
a capsule containing a liquid and a second reactant, said capsule being located within said housing;
wherein said liquid freezes at a first threshold temperature and expands upon freezing whereby said capsule fractures from the liquid expansion;
wherein said first and said second reactants combine on said first surface to produce a pigment of a second color upon mixing, said first and said second colors being different; and
wherein said first reactant is a salt of a weak acid-strong base or of a strong acid-weak base, and said second reactant is a water soluble reactant,
or wherein said first reactant is a water soluble reactant and said second reactant is a salt of a weak acid-strong base or of a strong acid-weak base;
and further comprising a second capsule located within said housing and optionally a third reactant;
wherein the formulation of said second capsule comprises a component that melts at a designated second threshold temperature;
wherein said second capsule contains said second reactant or said optional third reactant;
wherein when said optional third reactant is present, said third and first reactants combine to produce a pigment of a third color upon mixing, said third color being different from said first color;
wherein when said first reactant is a salt of a weak acid-strong base or of a strong acid-weak base, then when said optional third reactant is present, said third reactant is a water soluble reactant; and
wherein when said first reactant is a water soluble reactant, then when said optional third reactant is present, said third reactant is a salt of a weak acid-strong base or of a strong acid-weak base.

4. A device for indicating a transition across a threshold temperature comprising:
a housing,
a first surface, at least a portion of said first surface being of a first color;
a first reactant located on said first surface within said housing; and
a capsule containing a liquid and a second reactant, said capsule being located within said housing;
wherein said liquid freezes at a threshold temperature and expands upon freezing whereby said capsule fractures from the liquid expansion;
wherein said first and said second reactants combine to produce a pigment of a second color upon mixing, said first and said second colors being different; and
wherein said pigment is fluorescent.

5. A device for indicating a transition across a threshold temperature comprising:
a housing,
a first surface, at least a portion of said first surface being of a first color;
a first reactant located on said first surface within said housing;
a capsule containing a liquid and a second reactant, said capsule being located within said housing; and
a third reactant located on said first surface within said housing;
wherein said liquid freezes at a threshold temperature and expands upon freezing whereby said capsule fractures from the liquid expansion;
wherein said first and said second reactants combine to produce a first product that increases in concentration over time or with a temperature change or both, wherein said first product reacts with said third reactant to produce a color change of said first surface so as to provide an exposure time-temperature threshold indicator.

6. The device of claim 5 wherein said first reactant is urease enzyme, said second reactant is urea, said first product is ammonia, and said third reactant is a pH indicator.

7. A device for indicating a transition across a threshold temperature comprising:
a housing;
a first surface, at least a portion of said first surface being of a first color;
a first reactant located on said first surface within said housing;
a capsule containing a liquid and a second reactant, said capsule being located within said housing;
wherein said liquid freezes at a threshold temperature and expands upon freezing whereby said capsule fractures from the liquid expansion;
wherein said first and said second reactants combine on said first surface to produce a pigment of a second color upon mixing, said first and said second colors being different; and
wherein said first reactant and said second reactant are salts of a weak acid-strong base and a strong acid-weak base, respectively or are salts of a strong acid-weak base and a weak acid-strong base, respectively.