U.S. patent application number 10/444243 was filed with the patent office on 2004-01-15 for reactive decontamination formulation.
Invention is credited to Cisar, Alan J., Fyffe, James, Giletto, Anthony, Hitchens, G. Duncan, White, William.
Application Number | 20040009095 10/444243 |
Document ID | / |
Family ID | 22257340 |
Filed Date | 2004-01-15 |
United States Patent
Application |
20040009095 |
Kind Code |
A1 |
Giletto, Anthony ; et
al. |
January 15, 2004 |
Reactive decontamination formulation
Abstract
The present invention provides a universal decontamination
formulation and method for detoxifying chemical warfare agents
(CWA's) and biological warfare agents (BWA's) without producing any
toxic by-products, as well as, decontaminating surfaces that have
come into contact with these agents. The formulation includes a
sorbent material or gel, a peroxide source, a peroxide activator,
and a compound containing a mixture of KHSO.sub.5, KHSO.sub.4 and
K.sub.2SO.sub.4. The formulation is self-decontaminating and once
dried can easily be wiped from the surface being decontaminated. A
method for decontaminating a surface exposed to chemical or
biological agents is also disclosed.
Inventors: |
Giletto, Anthony; (College
Station, TX) ; White, William; (College Station,
TX) ; Cisar, Alan J.; (Cypress, TX) ;
Hitchens, G. Duncan; (Bryan, TX) ; Fyffe, James;
(Bryan, TX) |
Correspondence
Address: |
STREETS & STEELE
13831 NORTHWEST FREEWAY
SUITE 355
HOUSTON
TX
77040
US
|
Family ID: |
22257340 |
Appl. No.: |
10/444243 |
Filed: |
May 23, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10444243 |
May 23, 2003 |
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09096435 |
Jun 11, 1998 |
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6569353 |
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Current U.S.
Class: |
422/28 ;
252/186.1; 588/303 |
Current CPC
Class: |
A61K 8/25 20130101; A62D
3/38 20130101; B01J 20/06 20130101; A61K 8/46 20130101; A61Q 17/00
20130101; B01J 20/08 20130101; A62D 2101/02 20130101; B01J 20/103
20130101 |
Class at
Publication: |
422/28 ;
252/186.1; 588/200 |
International
Class: |
A61L 002/16 |
Goverment Interests
[0001] This invention was made with government support under grant
DE-FG03-97ER82420 awarded by the Department of Energy. The
government has certain rights in this invention.
Claims
What is claimed is:
1. A system for decontaminating toxic agents comprising: an
HSO.sub.5.sup.- ion; an oxidant capable of forming free hydroxyl
radicals; an activating species dispersed within the oxidant; and a
sorbent material, wherein the HSO.sub.5.sup.- ions, the oxidant and
the activating species are dispersed within the sorbent
material.
2. The system of claim 1, further comprising a dispenser having a
first compartment for holding the HSO.sub.5.sup.- ions and the
oxidant dispersed in the sorbent material and a second compartment
for holding the metal catalyst dispersed in the sorbent
material.
3. The system of claim 2, wherein the dispenser comprises a nozzle
having a mixer for mixing the HSO.sub.5.sup.- ions and the oxidant
with the activating species.
4. The system of claim 1, wherein the compound containing
HSO.sub.5.sup.- ions is selected from potassium monopersulfate,
sodium monopersulfate, ammonium monopersulfate, HSO.sub.5.sup.-
salts of alkali metals, and HSO.sub.5.sup.- salts of alkaline earth
metals and contaminants thereof.
5. The system of claim 1, wherein the oxidant is selected from
perborates, persulfates, organic peroxides, alkali metal peroxides,
alkali metal superoxides, alkaline earth metal peroxides and
combinations thereof.
6. The system of claim 1, wherein the activating species is
selected from finely divided metals, iron salts, iron hydroxides
iron oxyhydroxides, iron oxides, salts of copper, titanium,
chromium, vanadium, zinc, cobalt, nickel and mixtures thereof.
7. The system of claim 1, wherein the activating species is a
ferrous salt.
8. The system of claim 1, wherein the activating species is ferrous
sulfate.
9. The system of claim 1, wherein the sorbent material is selected
from silicon oxide, silica gel, silicon oxyhydroxides, aluminum
oxide, alumina gel, aluminum oxyhydroxides, aluminates and mixtures
thereof.
10. The system of claim 1, wherein the compound has an
HSO.sub.5.sup.- ion concentration of from about 0.1M to about
0.3M.
11. The system of claim 1, wherein the oxidant concentration is
from about 0.5M to about 1.5M
12. The system of claim 1, wherein the activating species
concentration is from about 0.1M to about 0.3M.
13. The system of claim 1, wherein the sorbent material
concentration is from about 5 wt % to about 15 wt %.
14. The system of claim 1, wherein the ratio of oxidant to
HSO.sub.5.sup.- ion is 90:10.
15. A method for decontaminating a toxic agent disposed on a
surface, comprising. reacting the toxic agent with a sufficient
amount of a formulation containing an HSO.sub.5.sup.- ion, an
oxidant, and an activating species for activating the oxidant for a
sufficient time and under conditions sufficient to produce a
reaction product having less toxicity than the toxic agent.
16. The method of claim 15, wherein the reaction product produced
is non-toxic.
17. The method of claim 15, wherein the formulation further
comprises a sorbent gel with the HSO.sub.5.sup.- ion, the oxidant,
and the activating species dispersed therein.
18. The method of claim 15, further comprising absorbing the toxic
agent into the sorbent gel; blocking any contact between the toxic
agent and the surrounding atmosphere; and removing the formulation
and reaction product from the surface without damaging the
surface.
19. The method of claim 15, wherein the formulation further
comprises a sorbent gel.
20. The method of claim 15, wherein the toxic agent is selected
from mustard gas, G-agents, V-agents, spores and mixtures
thereof.
21. The method of claim 15, wherein the compound containing
HSO.sub.5.sup.- ions is selected from potassium monopersulfate,
sodium monopersulfate, ammonium monopersulfate, HSO.sub.5.sup.-
salts of alkali metals, and HSO.sub.5.sup.- salts of alkaline earth
metals.
22. The method of claim 15, wherein the compound containing
HSO.sub.5.sup.- ions comprises 2KHSO.sub.5, KHSO.sub.4,
K2SO.sub.4.
23. The method of claim 15, wherein the oxidant is selected from
perborates, persulfates, organic peroxides, alkali metal oxides,
alkali metal peroxides, alkali metal superoxides, and alkaline
earth metal peroxides.
24. The method of claim 15, wherein the activating species is a
ferrous salt.
25. The method of claim 15, wherein the activating species is
ferrous sulfate.
26. A method for preparing a decontamination product comprising,
mixing a compound containing an HSO.sub.5.sup.- ion and an oxidant
capable of forming free hydroxyl radicals to form an oxidation
component; and providing an activating species for the oxidation
component in a separate container.
27. The method of claim 26, further comprising mixing the oxidation
component and the HSO.sub.5.sup.- containing compound with a
sorbent material.
28. The method of claim 26, further comprising mixing the
activating species with a sorbent material.
29. The method of claim 26, further comprising, providing a
dispensing element that mixes the oxidation component with the
activating species on demand.
Description
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention relates to a formulation for decontaminating
a variety of toxic agents.
[0004] 2. Background of the Related Art
[0005] Over many years, various highly toxic chemical and
biological warfare agents have been developed and stockpiled by
several nations. These weapons are very efficient in causing
multiple casualties and cannot easily be detected, making their
production and eventual deployment difficult to monitor. In
addition, these weapons cost relatively little to produce and are
easy to manufacture. In view of the hazards associated with these
agents, it is essential to have formulations which can rapidly and
efficiently decontaminate surfaces which have been exposed to these
chemical and biological warfare agents.
[0006] An important aspect of any containment strategy is to be
able to neutralize the threat using chemical decontamination
methods. Most chemical warfare agents (CWA's) and biological
warfare agents (BWA's) can be destroyed or rendered harmless by
suitable chemical treatments. Unfortunately, existing chemical
treatments for neutralization of biological and chemical agents
have significant drawbacks. A "universal" formulation that can
decontaminate all biological and chemical threats is not available.
Existing decontamination solutions are only effective against a
certain class of agents. In order to be effective, emergency
response personnel would need several types of decontaminants
available on-hand. Use of existing decontaminants under
inappropriate conditions can result in the formation of dangerous
by-products. For example, a dilute bleach solution is very
effective at destroying anthrax spores, but an extremely toxic
by-product is formed if used to destroy VX. Furthermore, some
chemicals, such as sodium hydroxide dissolved in organic solvents
are unsuitable for use in certain conditions because they corrode,
etch or erode materials.
[0007] Today, many different types of CWA's and BWA's are known.
The CWA's fall into three main classes: mustards (HD, a blistering
agent and HN.sub.3), and organophosphorous nerve agents
(acetylcholinesterase inhibitors) of the G (GA, GB, GD, GE, GF) and
V (VX, VE, VG, VM) type. BWA's can be classified into at least five
categories: viruses, bacteria, rickettsia, biological toxins, and
genetically engineered agents.
[0008] Most decontamination processes include some form of
hydrolysis. Hydrolysis of CWA's creates intermediates or oxidation
by-products of organophosphorous compounds that are sometimes more
toxic than the agent itself. While hydrolysis may be acceptable for
many organophosphorous compounds, it is not universally effective
against all of these compounds and great care must be taken to
first identify then treat the agent under the proper hydrolyzing
conditions.
[0009] The oxidation of neutral organo-phosphorous esters (OPEs)
usually involves atoms other than phosphorus. In compounds
containing sulfur, oxidation generally occurs at the sulfur atom In
unprotected nitrogen moieties, oxidation at nitrogen will occur and
may result in increased inhibition of acetylcholine esterase. From
a toxicological standpoint, random oxidation of organophosphorous
compounds at critical sites could result in the production of
better esterase inhibitors.
[0010] These considerations highlight the need for a system capable
of decontaminating a broad range of chemical and biological agents
without producing toxic by-products. In addition, there is a need
for a decontamination system that is compatible with most common
materials, easy to dispense and environmentally safe.
SUMMARY OF THE INVENTION
[0011] The present invention provides for a formulation for
decontaminating toxic agents such as chemical and biological
warfare agents and pesticides. The formulation comprises a sorbent
containing HSO.sub.5.sup.- ions, an oxidant, and an activator
dispersed in the oxidant for activating the oxidant. Preferably,
the compound containing HSO.sub.5.sup.- ions is selected from
potassium monopersulfate, sodium monopersulfate, ammonium
monopersulfate, HSO.sub.5.sup.- salts of other alkali metals, and
HSO.sub.5.sup.- salts of alkaline earth metals, most preferably
having the formula 2KHSO.sub.5, KHSO.sub.4, K.sub.2SO.sub.4, which
is commercially available as OXONE.
[0012] The oxidant can be selected from perborates, persulfates,
organic peroxides, alkali metal peroxides, alkali metal
superoxides, and alkaline earth metal peroxides, preferably
hydrogen peroxide. There are a number of known activators for
peroxide oxidation reactions. Some useful activators include iron
salts, as well as the salts of copper, titanium, chromium,
vanadium, zinc, cobalt, and nickel. Finely divided metals capable
of being readily oxidized to form metal cations are considered to
be within the scope of this invention. Preferably, the activator is
in the form of ferrous ions. In addition, phosphate ions may also
be used in the formulation to control the temperature of the
reaction.
[0013] The sorbent material may be selected from silicon dioxide,
silica gel, silicon oxyhydroxides, aluminum oxide alumina gel,
aluminum oxyhydroxides, aluminates, other metal oxides, other metal
oxyhydroxides, clay minerals and mixtures thereof, preferably,
filmed silica. The ideal sorbent is inert and has a high surface
area and capacity for absorbing or adsorbing the contaminants.
[0014] The HSO.sub.5.sup.- ion concentration can range from about
0.05M to about 0.5M, preferably from about 0.1M to about 0.3M. The
oxidant concentration can range from about 0.5M to about 5M,
preferably from about 0.5M- to about 1.5M. The activator
concentration can range from about 0.05M to about 0.5M, preferably
from about 0.1M to about 0.3M. The final sorbent material
concentration may be from about 3% to about 20% by weight,
preferably from about 5% to about 15% by weight.
[0015] A system for decontaminating toxic agents is also provided.
The system comprises an HSO.sub.5.sup.- ion, an oxidant capable of
forming free hydroxyl radicals, a metal catalyst or activator
dispersed within the oxidant, and a sorbent material, wherein the
HSO.sub.5.sup.- ions, the oxidant and the metal catalyst are
dispersed within the sorbent material. Preferably, a dispenser is
provided with a first compartment for holding the HSO.sub.5.sup.-
ions and the oxidant dispersed in the sorbent material and a second
compartment for holding the metal catalyst or activator dispersed
in the sorbent material. The dispenser may also have a nozzle with
a mixer for mixing the HSO.sub.5.sup.- ions and oxidant with the
metal catalyst or activator. The sorbent compounds containing
HSO.sub.5.sup.- ions, the oxidant, and the metal catalyst are
described above. Preferably, the ratio of oxidant to
HSO.sub.5.sup.- ion is 90:10.
[0016] In another embodiment of the present invention, there is
provided a method for decontaminating a toxic agent disposed on a
surface. The method includes reacting the toxic agent with a
sufficient amount of a solution containing an HSO.sub.5.sup.- ion,
an oxidant, and a metal catalyst or activator for activating the
oxidant for a sufficient time and under conditions sufficient to
produce a reaction product having less toxicity than the toxic
agent. Preferably, the reaction product produced is non-toxic. The
non-corrosive compound may include a sorbent gel with the
HSO.sub.5.sup.- ion, the oxidant, and the metal catalyst or
activator dispersed therein. Preferably, the toxic agent is
absorbed into the sorbent gel, which blocks any contact between the
toxic agent and the surrounding atmosphere. Once the
decontamination reaction has taken place, the compound and reaction
product can be easily removed from the surface without damaging the
surface. A variety of toxic agents can be decontaminated using this
method, including but not limited to mustard gas, G-agents,
V-agents, spores and mixtures thereof.
[0017] The compound containing HSO.sub.5.sup.- ions is preferably
selected from potassium monopersulfate, sodium monopersulfate,
ammonium monopersulfate, HSO.sub.5.sup.- salts of other alkali
metals, and HSO.sub.5.sup.-, salts of alkaline earth metals, most
preferably having the formula 2KHSO.sub.5, KHSO.sub.4,
K.sub.2SO.sub.4. The oxidant can be selected from perborates,
persulfates, organic peroxides, alkali metal peroxides, alkali
metal superoxides, and alkaline earth metal peroxides, the
preferred metal catalyst or activator is ferrous cations.
[0018] In yet another embodiment, there is provided a method for
preparing a decontamination product. The method includes mixing a
compound containing an HSO.sub.5.sup.- ion and an oxidant capable
of forming free hydroxyl radicals to form an oxidation component
and providing a metal catalyst or activator to bring about the
formation of hydroxyl radicals in a separate container. Preferably,
the oxidation component is mixed with a sorbent material and the
metal catalyst or activator is mixed with a sorbent material. A
dispensing element may be provided that mixes the oxidation
component with the metal catalyst on demand for easy application of
the decontamination product.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] So that the above recited features and advantages of the
present invention can be understood in detail, a more particular
description of the invention, briefly summarized above, may be had
by reference to the embodiments thereof which are illustrated in
the appended drawings. It is to be noted, however, that the
appended drawings illustrate only typical embodiments of this
invention and are therefore not to be considered limiting of its
scope, for the invention may admit to other equally effective
embodiments.
[0020] FIG. 1 is a graph showing the destruction of Malathion under
different conditions.
[0021] FIG. 2 is a graph showing the destruction of spores using
various oxidant formulations.
[0022] FIG. 3 is a bar graph showing the presence of intermediates
after treatment with a formulation of the present invention.
[0023] FIG. 4 is a bar graph showing the elimination of
intermediates after treatment with a formulation of the present
invention.
[0024] FIG. 5 is a bar graph showing the concentrations of the
Mustard surrogate, chloroethyl ethyl sulfoxide, and chloroethyl
ethyl sulphone over time after treatment with a formulation of the
present invention.
[0025] FIG. 6 is a liquid chromatogram of the remaining V-agent
surrogate concentration in a carpet swatch after treatment with a
formulation of the present invention.
[0026] FIG. 7 is a graph showing spore destruction after treatment
with a formulation of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0027] The present invention provides a universal decontamination
formulation and method for detoxifying chemical warfare agents
(CWA's), biological warfare agents (BWA's) and other toxic agents
without producing any toxic by-products, as well as,
decontaminating surfaces that have come into contact with these
agents.
[0028] One aspect of the invention provides a formulation that is
universally applicable to decontamination of both biological and
chemical agents. The formulation includes a sorbent material or
gel, such as fumed silica, a peroxide source such as, hydrogen
peroxide (H.sub.2O.sub.2), and a peroxide activator, such as
iron(II) sulfate, or salts of copper, titanium, chromium, vanadium,
zinc, cobalt, and nickel. When the formulation is applied to a
biological or chemical agent, the hydrogen peroxide component
reacts with ferrous cation to form hydroxyl radicals OH.. Hydroxyl
radicals react non-selectively and rapidly with most chemical
agents, decomposing them to harmless end products. Also included in
the formulation is a small amount of a second oxidant containing a
mixture of KHSO.sub.5, KHSO.sub.4 and K.sub.2SO.sub.4 available
from the DuPont de Nemoirs Company of Wilmington, Del., under the
trademark OXONE. OXONE substantially enhances the formulation's
effectiveness against biological agents. The sorbent component is
preferably formed of fumed silica (silicon dioxide), a low cost
bulk industrial thickening agent used in cosmetics and food
preparations. In addition to silicon dioxide, aluminum oxide or
titanium oxide may also be used as a delivery agent. Hydrogen
peroxide is a widely available low cost bulk commodity which is
used at concentrations of 3 wt % as a disinfectant for skin and
tissues. The residual gel is self-decontaminating and once dried
can easily b e wiped from the surface being decontaminated. In
addition, the residual gel will have a low environmental impact
because it contains only silica and small amounts of colloidal iron
oxide (rust).
[0029] Another aspect of the invention provides a formulation that
has universal chemical and biological decontamination capability.
The formulation of the present invention destroys all major classes
of CWA's including mustard agents, G-agents and V-agents, such as
Tabun (GA), Sarin (GB), Soman (GD), VX, Mustard (HD), as well as
bacterial spores, such as Botulinum and viral agents.
[0030] In addition to decontaminating chemical and biological
agents, the formulation is also effective against other toxic
agents such as pesticides. In the experiments shown below,
Demeton-s, while used as a v-agent surrogate, has been used in
pesticides. Malathion is also a commercially available
pesticide.
[0031] The formulation produces sufficient chemical degradation of
the CWA's and BWA's to eliminate them and leave no toxic
by-products. In addition, the formulation causes little or no
damage to the surfaces to which it is applied, making it suitable
for use on walls, carpets, and other surfaces that are susceptible
to corrosion or etching. The formulation is easily applied by
spraying, is highly sorptive and is effective at removing and
decontaminating the agents from the surface.
[0032] In yet another aspect of the invention, there is provided a
method for detoxifying chemical and/or biological warfare agents.
The agents are detoxified by reacting the toxic agent with a
sufficient amount of a non-corrosive compound containing an
HSO.sub.5.sup.- ion, an oxidant, and a metal catalyst or activator
for activating the oxidant for a sufficient time and under
conditions sufficient to produce a reaction product having less
toxicity than the toxic agent. Preferably, the conditions are
sufficient that the reaction products are non-toxic and
environmentally safe. The underlying surface that the agent is on
will also be decontaminated by this method. The reaction can be
carried out in an aqueous environment, however, the method
preferably includes absorbing the toxic agent into a sorbent gel
containing the non-corrosive compound, the oxidant, and the metal
catalyst or activator. The gel acts to form a barrier between the
toxic agent and the surrounding atmosphere, thereby containing the
toxic agent. Once the reaction is complete, the gel containing the
compound and the reaction product is removed from the surface
without causing any damage to the surface. Thus, the method is
effective for detoxifying the toxic agent, as well as
decontaminating the exposed surface. The formulation including the
gel containing the non-corrosive compound, the oxidant, and the
metal catalyst or activator, is effective in decontaminating
mustard gas, G-agents, V-agents, and bacterial spores
simultaneously.
[0033] The compound containing HSO.sub.5.sup.- ions is selected
from potassium monopersulfate, sodium monopersulfate, ammonium
monopersulfate, HSO.sub.5.sup.- salts of other alkali metals, and
HSO.sub.5.sup.- salts of alkaline earth metals or mixtures thereof.
Preferably, the compound containing HSO.sub.5.sup.- ions comprises
2KHSO.sub.5, KHSO.sub.4, K.sub.2SO.sub.4 and is sold under the
commercial name OXONE. OXONE has a powerful oxidation potential and
has seen limited use as a decontamination agent. It has been shown
that OXONE is effective against HD and VX type agents. However,
OXONE appears to be ineffective against G-agents. KHSO.sub.5, the
active ingredient in OXONE, is prepared by a variety of methods
involving either H.sub.2O.sub.2 and chlorosulfonic acid or
potassium persulfate and H.sub.2SO.sub.4. The chemical formula of
the compound is shown below. 1
[0034] The oxidant may be selected from perborates, persulfates,
organic peroxides, alkali metal oxides, alkali metal peroxides or
mixtures thereof. Preferably, the oxidant is hydrogen peroxide.
Preferably, the hydrogen peroxide is catalyzed or activated by a
metal, selected from iron and iron salts, preferably, the metal
activator is Fe.sup.2+ in the form of Fenton's reagent. The
oxidation of the toxic agents and their by-products is primarily
based on Fe.sup.2+ activated hydrogen peroxide.
[0035] The activated hydrogen peroxide reaction is given in Eq.
1.
Fe.sup.2++H.sub.2O.sub.2.fwdarw.Fe.sup.3++OH.+HO.sup.- (1)
[0036] yielding hydroxyl radicals (OH.), one of the most powerful
oxidants.
[0037] The decomposition of H.sub.2O.sub.2 is extremely sensitive
to catalysis or activation (both heterogeneous and homogeneous) by
a wide variety of substances.
H.sub.2O.sub.2.fwdarw.H.sub.2O+O.sub.2 (2)
[0038] Both Fe.sup.2+ and Fe.sup.3+ react with hydrogen peroxide.
The "classical" mechanisms for these reactions involve hydroxyl
radical intermediates that can attack organic compounds. The
classical reaction of Fe.sup.2+ with H.sub.2O.sub.2, known as the
Fenton reaction, generates HO. in the rate-limiting step (Eq. 3).
Reaction with another Fe.sup.2+ (Eq. 4) or reaction with an organic
compound may scavenge HO.. Typical rates of reaction between
hydroxyl radicals and organic materials are 10.sup.9-10.sup.10
(M.sup.-1 s.sup.-1).
Fe.sup.2++H.sub.2O.sub.2.fwdarw.Fe.sup.3++OH.+OH.sup.- (3)
OH.+Fe.sup.2+.fwdarw.Fe.sup.3++OH.sup.- (4)
[0039] Fe.sup.3+ decomposes H.sub.2O.sub.2 to O.sub.2 and H.sub.2O.
The classical "radical chain" mechanism proposed for simple
Fe.sup.3+(aq) systems (i.e., no complexing ligands other than
water) involves HO. and the hydroperoxyl radical (HO.sub.2.) by the
following steps, inclusive of Equations (3) and (4):
Fe.sup.3++H.sub.2O.sub.2.fwdarw.Fe--OOH.sup.2++H.sup.+ (5)
Fe--OOH.sup.2+.fwdarw.HO.sub.2.+Fe.sup.2+ (6)
Fe.sup.2++HO.sub.2..fwdarw.Fe.sup.3++HO.sub.2.sup.- (7)
Fe.sup.3++HO.sub.2..fwdarw.Fe.sup.2++O.sub.2+H.sup.+ (8)
HO.+H.sub.2O.sub.2.fwdarw.H.sub.2O+HO.sub.2. (9)
[0040] In the presence of excess peroxide, the concentration of
Fe.sup.2+ is small relative to the concentration of Fe.sup.3+,
since reaction (6) is generally much slower than reaction (3).
Reaction (9) is an additional mechanism for HO. scavenging.
[0041] Compared to HO., HO.sub.2. is much less reactive, and its
conjugate base O.sub.2..sup.- (pK.sub.a, 4.8) is practically
unreactive as a free radical. Carbon-centered radicals generated by
hydroxyl radical attack may react with O.sub.2, if present, to give
organoperoxy radicals (ROO.), which can decompose to form HO.sub.2.
or ultimately nonradical oxygenated products.
[0042] In addition to iron, it is preferred that the formulation
include phosphate ions. The phosphate ions act as a masking agent
that slows the release of the Fe.sup.2+ available for the
generation of OH. radicals from H.sub.2O.sub.2.
[0043] The ideal gel or delivery agent for the decontamination
formulation is one that is inert or non-reactive with the oxidizing
agents. Fumed silicon dioxide (SiO.sub.2) has shown goods results.
Fumed silica has an extremely small particle size (0.007 to 0.014
.mu.m), enormous surface area (about 200 m.sup.2/g), high purity
(99.8%), and a low bulk density (250 kg/m.sup.3). Fumed silica
performs the two primary functions of reinforcement and rheology
(flow) control in the present delivery system. Reinforcement
increases the strength or viscosity of various materials, such as
the decontaminating agents, allowing them to be used in a wider
number of applications, such as on ceilings and walls. The
viscosity of the gel can be easily tailored to suit a specific
situation. Fumed silica is prepared by gas/oxygen flame oxidation
of SiCl.sub.4 or methyltrimethoxysilane as shown in Scherer, G. W.
and Bachrnan, D. L. "Sintering of Low-Density Glasses: II,
Experimental Study." J. Amer. Ceramic Soc. 60, 239 (1977).
[0044] Fumed silica is widely available and is generally used in
small quantities in many products such as toothpaste, detergents,
food, coatings, adhesives, concrete, cosmetics, inks, plastics, and
various types of rubbers. Fumed silica acts to thicken, and suspend
solids. Fumed silica gel provides good surface coverage because of
its free flowing character and holds the reactive components of the
formulation in-place for extended periods. Sorption of the
contaminant into the gel matrix is highly effective because of the
enormous surface area the fumed silica provides and because of the
relatively large volume available for dissolution.
[0045] Six chemical surrogates (1 mustard, 3 G-agents, and 2
V-agents) were selected along with Bacillus subtilus globigii
spores, which is the standard surrogate for Bacillus anthracis
(anthrax) spores, for experiments with the decontamination system
of the present invention. The structure of the six chemical
surrogates used in these experiments are shown below. Initially,
only one V-agent surrogate (MAL) was selected for testing; however,
an additional V-agent surrogate, Dem-S, which more closely
resembles VX at the phosphorous was selected for testing. 2
[0046] The following examples serve to illustrate the invention and
are therefore not to be considered limiting of its scope.
MATERIALS USED IN EXAMPLES
[0047] Unless otherwise indicated, the following materials and
reagents were used in the examples described below.
[0048] Surrogates: Dimethylmethylphosphonate (DMMP) and
Chloroethylethyl-sulfide (CEES)-Aldrich Chemical Co., 1001 West
Saint Paul Ave., Milwaukee, Wis. 53233; Diethylmethylphosphonate
(DEMP); Diisopropylmethylphosphonate (DIMP)-Alfa Aesar, 30 Bond
St., Ward Hill, Mass. 01835; Malathion (MAL)-Pfaltz & Bauer,
172 E. Aurora St., Waterbury, Conn. 06708; Demeton-S
(Dem-S)-ChemService, 660 Tower Lane, West Chester, Pa. 19381; and
Bacillus subtilus (globigii) spores-STERIS Corp., 5960 Heisley
Road, Mentor, Ohio 44060.
[0049] Reagents: Hydrogen Peroxide (3 wt %)-Walmart, College
Station, Tex. 77840; Phosphoric Acid (85 wt %), and Dichloromethane
(Suitable for GC/MS)-Fisher Scientific, 711 Forbes Avenue,
Pittsburgh, Pa. 15219; Sodium Hypochlorite (13 wt %), OXONE,
Hydrogen Peroxide (30 wt %), Ferrous Sulfate Heptahydrate, Sodium
Hydroxide, Chloroethylphenyl Sulfide (CEPS) were all purchased from
Aldrich Chemical Co.
Example 1. CEES Oxidation at 50:1
[0050] 1.5 mL of freshly prepared gel containing 8 wt % fumed
silica suspended in a 0.1 M sodium phosphate buffer, pH=3.2, was
added to a 20 mL vial containing 0.13 grams FeSO.sub.4.7H.sub.2O
(0.45 mmol). The vial was shaken/swirled until all the iron had
gone into solution. 12 .mu.L CEES (0.1 mmol) was then added to the
vial and the vial was shaken/swirled. 0.51 mL H.sub.2O.sub.2 (30 wt
%, 4.5 mmol) and 77 mg OXONE (0.5 mmol) was added, the vial was
capped with a TEFLON lined cap and shaken to mix reagents. The vial
was allowed to stand throughout the reaction.
[0051] At the desired time, the reaction was quenched by the
addition of 20 mL dichloromethane followed by vigorous shaking for
2-3 minutes. 10 .mu.L CEPS (as the internal standard) was added and
the vial was shaken for another 3-4 minutes. The capped vial was
allowed to stand for 30 minutes and a 2 mL sample was withdrawn
from the lower, organic phase and placed in a 2 mL autosampler
vial.
Example 2. CEES Oxidation at 20:1
[0052] 1.5 mL of freshly prepared gel containing 8 wt % fumed
silica suspended in a 0.1 M sodium phosphate buffer, pH=3.2, was
added to a 20 mL vial containing 56 mg FeSO.sub.4.7H.sub.2O (0.2
mmol). The vial was shaken/swirled until all the iron had gone into
solution. 12 .mu.L CEES (0.1 mmol) was then added to the vial and
the vial was shaken/swirled. 0.57 mL H.sub.2O.sub.2 (12 wt %, 2
mmol) and 31 mg OXONE was added, the vial was capped with a TEFLON
lined cap and shaken to mix reagents. The rest of the method was
identical to that mentioned above in Example 1.
[0053] CEES Detection and Quantitation
[0054] A Varian Saturn 4D GC/MS/MS System was used to detect and
quantitate CEES and CEPS (internal standard). The Saturn 4D system
is composed of: (1) Model 8200 Autosampler; Star 3600 CX GC with a
Model 1094 Septum-equipped Programmable Injector (SPI); (2) 30
meter.times.0.25 id.times.0.25 .mu.m stationary phase DB-5MS
capillary column or equivalent; (3) Saturn 4D MS/MS Ion Trap Mass
Detector; and (4) a Digital PC Computer equipped with NIST MS
database software for control, identification and data processing.
All samples were injected in triplicate to minimize variations from
individual runs. The GC conditions were: injector temperature:
270.degree. C.; segment 1: 80-180.degree. C. at 8.degree. C./min;
segment 2: 180.degree. C. and hold for 3 min; transfer line:
180.degree. C.; manifold temperature: 250.degree. C. The MS
settings were: mass range: 50-180 m/z(mass to charge ratio); scan
time: 1.000 seconds; segment length: 15 minutes; Fil/Mult(Filament
Multiplier) delay: 2.6 minutes; peak threshold: 1 count; background
mass: 10 m/z. The carrier gas was ultra-high purity Helium, greater
than 99.999% purity with a linear velocity of 25 cm/min. An
additional oxygen trap was added to the line to protect the column
and ion trap. The sample injection volume for all samples was 0.3
.mu.L.
Example 3. DMMP, DEMP, and DIMP Oxidation at 100:1
[0055] 1.5 mL of freshly prepared gel containing 12 wt % fumed
silica suspended in a 0.1 M sodium phosphate buffer, pH=3.2, was
added to each of three 40 mL vials containing 12 .mu.L DMMP, 15
.mu.L DEMP and 18 .mu.L DIMP, respectively. A 0.5 mL water solution
containing 0.28 g FeSO.sub.4.7H.sub.2O was added to the vials. The
vials were shaken/swirled to mix reagents. 1.03 mL H.sub.2O.sub.2
(30 wt %) and 0.154 g OXONE were added to each vial, the vials were
capped with a TEFLON lined cap and shaken to mix reagents. Each
vial was allowed to stand throughout the reaction. By allowing each
vial to stand, removal of the surrogate from glass was
simulated
[0056] At various time intervals of interest, the reaction was
quenched by the addition of 20 mL dichloromethane followed by
vigorous shaking for 2-3 minutes. 10 .mu.L DMMP (as the internal
standard) was added and the vial was shaken for another 3-4
minutes. (When the destruction of DMMP was being measured, DEMP was
used as the internal standard). The capped vial was allowed to
stand for 30 minutes and a 2 mL sample was withdrawn from the
lower, organic phase and placed in a 2 mL autosampler vial.
[0057] DMMP, DEMP, and DIMP Detection and Quantitation
[0058] The same GC/MS system used to detect and quantify CEES was
used for the detection and quantitation of DMMP, DEMP, and DIMP.
The GC conditions were: injector temperature: 270.degree. C.;
segment 1: 50-200.degree. C. @ 8.degree. C./min; segment 2:
200.degree. C. and hold for 2 min; transfer line: 180.degree. C.;
manifold temperature: 250.degree. C. The MS settings were: mass
range: 40-175 m/z; scan time: 0.500 seconds; segment length: 8
minutes; Fil/Mult. delay: 4.0 minutes; peak threshold: 1 count;
background mass: 10 m/z.
Example 4. Dem-S at 100:1 and MAL Oxidation at 1000:1
[0059] 2 mL of freshly prepared gel containing 6 wt % fumed silica
and 12.6 mg/mL FeSO.sub.4.7H.sub.2O was added to a 20 mL vial
containing 24 .mu.L Dem-S and a vial containing 2.5 .mu.L MAL. 15
mg of OXONE and 100 .mu.l of 30 wt % H.sub.2O.sub.2 were
simultaneously added to each vial and vortexed. At the desired
time, the reaction was quenched by the addition of 18 mL of
quenching solution which consisted of 10% isopropanol, 27%
acetonitrile, and 63% water (actually 10% isopropanol and 90%
liquid chromatograph mobile phase).
[0060] Dem-S and MAL Detection and Quantitation
[0061] The quantitation of Dem-S and MAL was accomplished primarily
by liquid chromatography (LC). The LC system was composed of two
Shimadzu LC-6 reciprocating piston pumps, a Rheodyne 6-port manual
injector fitted with a 100 .mu.l injection loop, an Econosphere 3
.mu.m, 4.6.times.25 mm C18 column, and a variable wavelength
Shimadzu 6AV UV/VIS detector. The whole system was controlled by
EZChrom software running on an IBM compatible PC with an Intel
486SX processor. The mobile phase for both Dem-S and MAL was 30%
acetonitrile/70% water at 2.0 mL/min. The wavelength monitored was
210 nm. All gel samples were routinely passed through a 0.45 .mu.m
filter to remove the gel prior to performing LC.
Example 5. Bacillus Subtilus Spore Oxidation
[0062] 100 .mu.L of 1.3.times.10.sup.9 spores/mL
(1.3.times.10.sup.8 spores) were heat fixed onto autoclaved glass
slides. After exposure to the decontaminantal gel, the slides were
washed with 30% ethanol to quench the reaction and were placed into
a test tube containing 3 mL of 20 mM potassium phosphate buffer, pH
7.1. A control was also tested by treating slides with the 0.1 M
phosphate pH 3.2 buffer. The control was exposed for the duration
of the experiment and was similarly washed with 30% ethanol and
placed into a test tube containing 3 mL of 20 mM potassium
phosphate buffer, pH 7.1.
[0063] Bacillus Subtilus Spore Detection and Quantitation
[0064] After collecting slides at all time points, the test tubes
containing the slides were sonicated for one hour to extract the
spores off of the slides. The buffer containing the extracted
spores was then serially diluted to 10.sup.-6 and 100 .mu.L
duplicates were plated onto nutrient agar out to a dilution factor
of 10.sup.-7. The plates were incubated for 24 hours and colony
forming units were counted. This method has a 99.8% spore recovery
rate. The maximum number of spores plated equals the number of
spores on the slide (1.3.times.10.sup.8) divided by the spore
recovery volume (3 mL) times the volume plated (0.1 mL) which
equals 4.3.times.10.sup.6. The detection limit is one spore per
plate out of 4.3.times.10.sup.6 which corresponds to a 6.6 log (log
4.3.times.10.sup.6-log 1) or 99.99998% detection limit.
Example 6. Spiking and Decontamination of Carpet Swatches
[0065] A sample of commercially available carpet was cut into
squares having sides 2 1/2 inches long. Two squares were used for
the experiment. Each of the two squares was spiked with 27 .mu.l of
Dem-S (about 30 mg, 0.12 mmole). The 27 .mu.l was distributed as
nine 3 .mu.l spots arranged in a 3.times.3 matrix on the square.
Each swatch was placed in a glass beaker. To the control swatch 25
mL quenching solution (10% isopropanol/90% LC mobile phase) was
added and to the other swatch 25 mL of freshly prepared
decontamination gel was added. The gel concentration was 3.1 wt %
H.sub.2O.sub.2, 2.5 wt % FeSO.sub.4.7H.sub.2O, 1.5 wt % OXONE, and
6 wt % fumed silica. This corresponded to a 200:1 molar excess of
oxidant to surrogate. After 5 minutes had elapsed, 25 mL of
quenching solution was added to each swatch for a total volume of
50 mL in each. 3 mL of each was filtered and injected into the LC
system previously described. Both swatches were removed from the
beakers and the treated swatch was washed with 25 mL of water to
remove the gel. (I deleted the last sentence from this
paragraph)
Example 7 Material Compatibility Testing
[0066] In addition to the carpet decontamination mentioned above,
other materials were treated with the gel, prepared according to
Example 10, to determine material compatibility. A single 150 g
piece of concrete was placed in a beaker and submerged in
decontaminating gel. After an hour of exposure, the concrete was
removed, rinsed with water and visually examined for damage
compared to an adjacent untreated sample.
Example 8
[0067] Similarly, a 1 inch.times.2 inch coupon of aluminum was
submerged for an hour in decontaminating gel prepared according to
Example 10. After being rinsed with water, the coupon was closely
examined next to an untreated aluminum coupon.
Example 9
[0068] Painted dry-wall coupons were also exposed to gel prepared
according to Example 10. First the coupons were prepared by
applying three coats of red indoor latex enamel paint to a large
sheet of 3/8 inch dry-wall. Both paint and dry-wall were purchased
at a local home improvement store. A section of the sheet was cut
into square coupons having 2 1/2 inch sides. To the painted surface
of a single piece of painted dry-wall was placed 1 mL of
decontaminating gel. This limited volume was selected to expose
only the paint on the coupon to the gel and not the unpainted sides
of the coupon. The gel was allowed to dry overnight (about 16 hrs).
The next day, the dried gel was wiped clean from the painted
surface with a damp cloth. The painted surface was visually
inspected for noticeable damage adjacent to a similar coupon that
was untreated. Similarly, a carpet swatch, identical to those
mentioned above, was treated with 1 mL of gel overnight. The next
day the swatch was rinsed and compared to a similar untreated
swatch.
Example 10 Spray Testing
[0069] The decontamination formulation was prepared by mixing 2.71
L of 0.1 M sodium phosphate buffer pH 3.2, 0.14 L deionized water,
121.6 g of FeSO.sub.4.7H.sub.2O and approximately 450 g of fumed
silica in a 10 pt. container. The silica was added last with the
aid of an impeller until the mixture was as thick as possible
before adding the following reagents. In a separate container,
73.15 g of OXONE, 0.5 L of 30 wt % H.sub.2O.sub.2 and approximately
100 g of silica were mixed together until the gel was a thick
consistency. The two gels were then mixed together to give a final
gel concentration of about 14% by weight.
[0070] Results
[0071] The experiments performed in Examples 1-4 compared activated
peroxide to OXONE for the oxidation of surrogates. OXONE rapidly
oxidized CEES and Dem-S to completion in 5 minutes, but could only
eliminate 11% of DEMP after 30 min at a 100:1 molar excess of OXONE
to surrogate. Catalyzed peroxide (also at 100:1) produced similar
rapid destruction of CEES and Dem-S and also eliminated 77% of DEMP
in 5 minutes. More importantly, when the oxidants were combined in
a 90:10 ratio of catalyzed or activated peroxide:OXONE, the
resulting formulation eliminated 98.8% of DEMP in 5 minutes while
maintaining its effectiveness against CEES and Dem-S (Table 1).
[0072] In addition to the synergy observed in the destruction of
chemical agents, the 90:10 combination of peroxide to OXONE also
proved substantially more effective against spores than either of
the oxidants alone (See Example 11 below).
[0073] 1. Chemical Decontamination
[0074] The ability of the 90:10 peroxide to OXONE, formulation to
destroy all six chemical surrogates in the gel is described below.
The results are summarized in Table 1. Below each of the surrogates
is listed the initial concentration of peroxide, OXONE, iron, and
surrogate in the reaction, followed by the percent of initial
surrogate remaining in the reaction at different time points.
[0075] It is important to note that both the concentrations of
oxidant and surrogates in the reactions listed in Table 1 are
environmentally safe. A 0.9 M solution of peroxide is equivalent to
about 3 wt % which is equivalent to peroxide solutions available at
local supermarkets and used as a topical disinfectant and
mouthwash. The highest concentration of peroxide in the table is
2.3 M or about 8 wt %. The initial concentration of surrogates used
in the reactions listed in the table range from 1 to 50 mM which is
in the range of the concentrations typically encountered under
field decontamination situations (10.sup.-2-10.sup.-1M).
[0076] All of the reactions were performed in a mixture whose total
peroxide concentration equaled 0.9 M. CEES (at a total oxidant to
CEES ratio of 20:1), Dem-S and MAL where all decontaminated at this
concentration. In the CEES (50:1), however, the GC/MS detection
limit for CEES prevented using 20 mM surrogate with the 0.9 M
peroxide/0.1 M OXONE decontamination gel. A higher concentration of
CEES was required and to preserve the molar ratio of oxidant to
surrogate, a more concentrated gel formulation was used. Similarly,
the GC/MS detection limit prevented using a 10 mM initial
concentration for the G-agent surrogate experiments and higher
concentrations of both surrogate and oxidants were necessary to
preserve. the 100:1 molar ratio of oxidant to surrogate.
[0077] From the data presented in Table 1, it is obvious that the
gel is a very effective decontaminant because of the six surrogates
listed in the table, detectable amounts of CEES and Dem-S are not
present at 3 minutes and detectable amounts of DEMP and DIMP are
not present after 10 minutes. DMMP is reduced to less than 1% in 30
minutes and MAL, a typically very difficult surrogate to oxidize,
is reduced to about 6% of its original concentration in 90
minutes.
1TABLE 1 Representative chemical surrogates from the three main
classes of chemical warfare agents are destroyed with the gel
formulation in less than 90 minutes. Numbers in the table express
the percent of surrogate remaining at the times listed. Mustard
Surrogate G-Agent Surrogates V-Agent Surrogates CEES CEES DMMP DEMP
DIMP Dem-S MAL 0.9 M H.sub.2O.sub.2 1.8 M H.sub.2O.sub.2 2.3 M
H.sub.2O.sub.2 2.3 M H.sub.2O.sub.2 2.3 M H.sub.2O.sub.2 0.9 M
H.sub.2O.sub.2 0.9 M H.sub.2O.sub.2 0.1 M OXONE 0.2 M OXONE 0.25 M
OXONE 0.25 M OXONE 0.25 M OXONE 0.1 M OXONE 0.1 M OXONE 0.1 M
Fe.sup.2+ 0.18 M Fe.sup.2+ 0.25 M Fe.sup.2+ 0.25 M Fe.sup.2+ 0.25 M
Fe.sup.2+ 0.09 M Fe.sup.2+ 0.09 M Fe.sup.2+ 6 wt % silica gel 6 wt
% silica gel 6 wt % silica gel 6 wt % silica gel 6 wt % silica gel
6 wt % silica gel 6 wt % silica gel Time 50 mM CEES 40 mM CEES 25
mM DMMP 25 mM DEMP 25 mM DIMP 10 mM Dem-S 1 mM MAL (min) (20:1)
(50:1) (100:1) (100:1) (100:1) (100:1) (1000:1) 0 100% 100% 100%
100% 100% 100% 100% 3 71% ND -- -- -- ND -- 5 59% ND 4.7% 1.2% 0.2%
-- 18% 10 -- -- -- ND ND ND 15 -- ND 5.7% ND ND -- 13% 20 -- -- --
-- -- ND 30 0.6% ND 0.9% ND ND -- -- 60 -- -- -- -- -- ND 90 ND --
-- ND ND ND 6.3% ND - None detected (less than 0.1%)
[0078] Inspection of Table 1 reveals that DMMP is a more persistent
surrogate than either DEMP or DIMP, although the reason for this
observation is currently unknown. In the literature, there are
examples of the decontamination of GB and GD in OXONE solutions. It
was reported that neither oxidation nor displacement of the OR
groups is observed in solutions containing 50 mM agent and 100 mM
OXONE at pH 2. Yang, Y. C., Baker J. A. & Ward, J. R., Chem.
Rev. 1992 Vol. 91 p. 1729-1743. In fact, simple hydrolysis of the
P-F bond to form the corresponding phosphonic acids is the
exclusive hydrolysis pathway and results in greater than 90%
destruction of GB in 2 hours and greater than 90% destruction of GD
in 5 hours. In the reactions described in Table 1, the initial
surrogate concentration is 25 mM; the initial OXONE concentration
is 250 mM; and the pH is about 2. Of course, peroxide and iron
catalyst or activator are also present resulting in a large excess
of oxidant to surrogate and greater than 90% destruction of all
surrogates occurs in less than 5 minutes. With the large excess of
oxidant present in the reactions listed in Table 1, it is possible
that oxidation of the G-agent surrogates is occurring.
[0079] The most likely mechanism of destruction of the G-agent
surrogates in the reactions in Table 1 is by hydrolysis,
particularly when considering that DMMP is the most persistent of
the three surrogates. Hydrolysis of the surrogates involves an
S.sub.N2 attack on the phosphorous atom resulting in inversion
about the phosphorous and release of the OR group generating the
corresponding phosphonic acid. When comparing the three G-agent
surrogates and the chemistry of an S.sub.N2 attack on each, it is
apparent that DMMP should be the most persistent since it has the
least stable leaving group, -Omethyl. Conversely, DIMP should be
the easiest of the three to destroy because it has the best leaving
group, -Oisopropyl. The data in Table 1 certainly agrees with this
trend.
[0080] Dem-S, which more closely resembles VX at the phosphorous
group, was no longer detected at 3 min. In addition to the sulfur
directly bound to the phosphorous, Dem-S has a highly accessible
sulfur atom in the long hydrophobic chain and it is this sulfur
that is the most likely the first atom to be oxidized in the
molecule followed by the sulfur proximal to the phosphorous.
[0081] Conversely, MAL persisted after 90 minutes when exposed to a
1,000 fold molar excess of oxidant. While collecting data for MAL
presented in the above table, small droplets were observed in the
gel suggesting that the poor solubility of MAL in the aqueous
decontaminating solution could be the reason for the slow kinetics
of oxidation observed. Therefore, an additional MAL oxidation
experiment was performed to examine the ability of a fluorinated
surfactant (FC-99, 3M Specialty Chemicals Division) to enhance the
solubility and therefore, oxidation of MAL. The gel was omitted
from this experiment in order to carefully observe whether MAL was
completely solubilized in the test samples. In addition, the
concentration of MAL was increased by a factor of 20 (20 mM) when
compared to the reaction described in Table 1. This decreased the
molar excess of oxidant from 1,000:1 to 50:1.
[0082] In the absence of surfactant, MAL droplets were observed in
solution and as shown in FIG. 1, 85% of MAL was still present after
20 minutes. This data is certainly comparable to that presented in
Table 1. However, in the sample that contained 0.025% FC-99, MAL
droplets were still visible in the decontaminating solution but a
noticeable enhancement of MAL destruction was observed. When FC-99
was increased to 0.50% in the decontaminating solution, MAL
droplets were not observed in solution and 80% of the MAL was
destroyed in 20 minutes, certainly a substantial enhancement
considering 20 times more MAL was oxidized with the same amount of
oxidant. This data suggests that the solubility of MAL in aqueous
solution may be a barrier to oxidation and that by increasing MAL
solubility, decontamination levels comparable to other surrogates
can be achieved. A small amount of non-oxidizable surfactant and/or
cosolvent (i.e. acetonitrile) could be used as additional
ingredients in the decontamination solution to enhance destruction
of very hydrophobic agents including thickened agents.
[0083] 2. Biological Decontamination
[0084] The data represented in Table 1 and FIG. 1 show that the
decontamination gel can destroy six widely acceptable chemical
surrogates at battlefield relevant concentrations. However, a
universal decontaminant must also be able to destroy biological
warfare agents. Many biological warfare agents, such as
Staphylococcal enterotoxin and substance P, are proteinaceous and
highly susceptible to chemical oxidation. Small changes in the
molecule can dramatically destabilize the overall three dimensional
structure, rendering the agents harmless. A substantial challenge
in biological warfare agent decontamination are bacterial
endospores.
Example 11
[0085] Bacillus subtilus globigii spores, a surrogate for Bacillus
anthracis (anthrax). 1.3.times.10.sup.8 spores were heat fixed onto
a glass slide and the slide was submerged into 8 mLs of either (a)
1.3 M catalyzed or activated peroxide, (b) 0.13 M OXONE; (c) 0.13 M
hypochlorite; or (d) a combination of 1.3 M catalyzed or activated
peroxide and 0.13 M OXONE. The results of this experiment are
presented in FIG. 2 with the detection limit representing 10
spores/mL or a 99.99998% reduction in surviving spores (a 6.6 log
reduction). The figure shows that hypochlorite is the most
effective, eliminating all detectable spores within the first 5
minutes. The decontamination solution was almost as effective,
eliminating all detectable spores by the next time point (15
minutes).
[0086] It is significant that catalyzed or activated peroxide and
OXONE together gave substantially faster spore deactivation than
either of them used individually. It is believed that the peroxide,
at a relatively high concentration, is able to penetrate the spore
coat increasing its permeability to OXONE. In this way, OXONE can
then exert a more potent biocidal effect on the spore than if it
were used on its own. Regardless of the mechanism of spore
deactivation, the results shown in FIG. 2 clearly demonstrate that
a catalyzed or activated peroxide-OXONE formulation is suitable as
a decontaminant for biological as well as chemical agents. Data
shown later confirm that the spore deactivation rates can be
achieved in the gel formulation as well as in the liquid medium
used in FIG. 2.
Example 12 Elimination of By-Products: Liquid Formulation
Studies
[0087] An experiment was performed to determine if the standard
oxidation formulation produced chloroethyl ethyl sulfoxide,
chloroethyl ethyl sulfone, or any other by-product during CEES
oxidation and more importantly if these by-products persisted.
Initially, this experiment was performed in the liquid state and
the ratio of oxidant to CEES was 10:1. The reaction mixture was
extracted into dichloromethane and injected into the GC/MS system
for peak quantitation and identification. The experiment compared
catalyzed or activated peroxide to OXONE and a combination of the
two oxidants. Data was collected at 3 minutes and 90 minutes the
peak areas of CEES and the four by-products are shown in FIG. 3 (3
minutes) and FIG. 4 (90 minutes).
[0088] The three decontaminating formulations presented in FIG. 3,
did not generate any of the dechlorinated intermediates, in the
hypochlorite oxidation of CEES. The results from this experiment
demonstrate that a combination of catalyzed or activated peroxide
and OXONE is better than either oxidant alone. As shown in FIG. 3,
37% of the CEES is destroyed by catalyzed or activated peroxide,
100% by OXONE and 69% by the 90:10 catalyzed or activated
peroxide:OXONE combination. In this regard, OXONE is clearly
superior. However, no by-products, are detected in the catalyzed or
activated peroxide oxidation of CEES while a substantial amount of
chloroethyl ethyl sulfone is detected in the OXONE oxidation of
CEES. It is important to remember that the corresponding
intermediate in the oxidation of mustard is
bis(2-chloroethyl)sulfone which is reported to be the most toxic of
the S-oxidation products. By-products in the catalyzed or activated
peroxide:OXONE combination are detected but in very small
amounts.
[0089] As shown in FIG. 4, by 90 minutes both catalyzed or
activated peroxide alone and the catalyzed or activated peroxide:
OXONE combination have completely eliminated CEES. The toxic
sulfone detected in the OXONE oxidation of CEES at 3 minutes is
still present. The small amounts of the sulfoxide and the sulfone
present at three minutes (FIG. 3) in the catalyzed or activated
peroxide, OXONE mixture have decreased by 90 minutes. These
experiments provide a good example of why the mixed oxidant
formulation is used for the decontamination gel. The mixed oxidant
(catalyzed or activated peroxide plus OXONE) provides both rapid
degradation of CEES while considerably reducing and practically
eliminating by-products. The four main by-products identified in
the oxidation of CEES have the following structures: 3
[0090] Chloroethylethylsulfone is particularly undesirable since
the corresponding intermediate in the oxidation of mustard
(bis(2-chloroethyl)sulfone) is extremely toxic.
Example 13 Elimination of By-Products: Gel Formulation Studies
[0091] In this experiment, the mixed oxidant experiment in Example
12 was repeated using the gel. Additional time points were
collected to more closely monitor the formation and subsequent
disappearance of the by-products with time. The results from this
experiment appear in FIG. 5. The bars in the figure represent the
concentration of CEES with time as determined by peak areas in the
GC chromatogram. When the liquid and gel oxidation of CEES are
compared, it is apparent that the destruction of CEES occurs more
slowly in the gel. At three minutes in the liquid formulation, only
31% of the original CEES remained (See FIG. 3), while 67% of the
original CEES remained in the gel formulation. Nevertheless, at
ninety minutes, in either formulation, no CEES was detected and
only small quantities of by-products were observed.
[0092] As expected, this experiment suggests that the
decontamination rate is inversely proportional to the viscosity of
the gel, possibly implicating diffusion as a rate limiting factor
in decontamination. Therefore, the decontamination data collected
in the gel from Table 1 could be even faster if the amount of fumed
silica was decreased in the formulation.
Example 14 Decontamination of a Carpet Swatch Contaminated with VX
Surrogate and Additional Material Compatibility Testing
[0093] Dem-S was selected as the VX surrogate with which to spike
the carpet swatches. Two carpet swatches of identical size (2 1/2
inches.times.2 1/2 inches) were each spiked with 27 .mu.L Dem-S to
provide a contamination level equivalent to 80 lethal percutaneous
doses of VX per square foot of carpet. One swatch was treated with
25 mL of decontaminating gel (0.9 M H.sub.2O.sub.2, 0.1 M OXONE,
0.09 M FeSO.sub.4 and 6 wt % gel) for 5 minutes and the other was
untreated. Dem-S was recovered from each swatch and analyzed by
liquid chromatograph. FIG. 6 reveals the extent of the
decontamination. The chromatogram for the untreated swatch reveals
that the Dem-S extracted from the untreated carpet elutes at about
9.7 minutes. (Approximately 85% of the Dem-S was recovered from the
untreated carpet swatch when compared to Dem-S standards.) The
chromatogram from the extract of the decontamination gel treated
carpet shows that greater than 99.5% of the recovered Dem-S was
destroyed by the decontamination gel.
[0094] After the treated swatch was extracted and a sample of the
extract was injected into the liquid chromatograph system, the
swatch was washed with 25 mL of water to remove the gel. Close
examination of the treated swatch revealed that spots in the carpet
that may have once been white were slightly yellow as a result of
the iron oxide (rust) formed during the decontamination process.
However, subsequent washing with water removed virtually all of the
yellowish color. A similar washing process can certainly be
accomplished in the real world with a commercial carpet
cleaner.
Example 15
[0095] Two mL of decontaminating gel (oxidant concentrations of 1 M
H.sub.2O.sub.2 and 0.1 M OXONE) was placed on the surface of one
drywall coupon. The gel was allowed to remain on the coupon
overnight. The following day, the dried gel was wiped from the
surface of the painted dry-wall coupon with a damp cloth and
visually inspected for damage as compared to an untreated coupon.
It was clearly difficult to tell the two coupons apart.
[0096] In addition to the carpet and painted dry-wall, pieces of
concrete and aluminum coupons were also exposed to the gel with no
noticeable damage and/or discoloration.
Example 16 Application Method and Spray Testing
[0097] Bacillus subtilus spores were heat fixed onto glass slides
and affixed to a large outdoor wall. All the components of the gel
were mixed and quickly poured into a 2.5 gal water fire
extinguisher fitted with a garden hose nozzle. Once the vessel was
pressurized to 100 psi, the premixed gel was dispensed through the
nozzle and onto the wall on which the spore coated slides were
affixed from a distance of about 15 feet. The results from this
spray demonstration are presented in FIG. 7.
[0098] The gel dispensed from the vessel, through the nozzle, and
onto the contaminated wall reduced the spore count to undetectable
levels in 3 minutes. The observation that spore destruction starts
off slowly is a phenomena commonly observed with ozone destruction
of spores and most likely represents a delay associated with spore
coat penetration.
[0099] Summary and Discussion
[0100] 1. The Decontaminating Gel is Universal
[0101] Six surrogates representing the three major classes of
chemical warfare agents were successfully destroyed by the gel
formulation. The gel was also effective at rapidly deactivating
Bacillus subtilus spores, a surrogate for anthrax. Bacterial
endospores are known to be the most resistant life forms to
chemical decontaminates. They are used as standard test biological
indicators for validation of sterilization/disinfection procedures
by medical device manufacturers. The ability to deactivate spores
indicates a biocide's ability to kill all known microorganisms.
[0102] The oxidative destruction of HD and VX under acidic
conditions has been previously reported, but those same conditions
failed to effectively destroy G-agents. The formulations of the
present invention demonstrate that a combination of oxidants can
destroy, surrogates of all three major chemical classes and
bacterial endospores.
[0103] 2. The Combination of Catalyzed or Activated H.sub.2O.sub.2
and OXONE Work Synergistically
[0104] The results of the experiments demonstrate that the
combination of catalyzed or activated peroxide and OXONE work
better than either oxidant alone. The combination of oxidants
resulted in a rapid destruction of CEES and all detectable
by-products. Since the hydroxyl radicals generated in the gel
formulation are potent and indiscriminate oxidizing agents, it is
probable that by-products of other agents are also rapidly
destroyed. In addition, the combination of oxidants resulted in a
level and rate of spore decontamination better than either oxidant
alone and comparable to hypochlorite, a highly effective spore
decontaminant.
[0105] 3. The Concentration of Oxidant in the Gel Formulation
[0106] In most of the decontamination experiments performed, the
concentration of peroxide in the gel was 0.9 M or 3.1 wt % which is
equivalent to the over-the-counter solution used for topical
disinfection and mouthwash. In a few examples, gels containing
higher oxidant concentrations were used only because of GC/MS
detection limits. In addition, this mild gel formulation was
successful at decontaminating surrogates at concentrations similar
to those encountered in battle field scenarios.
[0107] Based on the information obtained from the Examples, Table 2
was prepared to demonstrate the decontamination potential of 10 L
of gel versus six current chemical and biological warfare agent
threats. The amount of surrogate successfully decontaminated was
converted to minimum decontamination potential of chemical and
biological warfare agents. The decontamination potential of 10 L of
gel is expressed in quantity of agent and number of lethal doses
decontaminated.
[0108] It is estimated that 10 L of the decontaminating gel can
coat 10 m.sup.2 (100 ft.sup.2) of surface with a 1 mm thick gel.
Assuming the distribution of the agent is uniform on the surface,
10 L of gel can decontaminate 100 ft.sup.2 of surface contaminated
with 43 lethal percutaneous doses of VX per square foot.
2TABLE 2 The decontaminating gel is estimated to be very effective
against six major chemical/biological warfare threats. Minimum
Number of Lethal Decontamination Lethal Doses 10 L of Potential of
Dose of Gel can Agent 10 L of Standard Gel Agent Decontaminate HD
32 g 4.48 g.sup.a 7 Tabun 16 g 1.61 g.sup.a 10 Sarin 14 g 1.96
g.sup.a 7 Soman 18 g 1.26 g.sup.a 14 VX 26 g 6 mg.sup.a 4300
anthrax spores 2.5 mg .about.1 .mu.g.sup.b 2500 .sup.apercutaneous;
.sup.binhalation
[0109] 4. Refining the Catalyzed or Activated Peroxide Reaction
[0110] The production of hydroxyl radicals from hydrogen peroxide
is an exothermic reaction. When the concentrations of peroxide are
low (less than 1 M), the heat generated is hardly detectable by
touch. However, at higher peroxide concentrations, the temperature
of the catalyzed or activated peroxide solution can become quite
warm and even hot if the peroxide concentration is high enough.
Including phosphate ions in the catalyzed or activated peroxide
solution has been found to considerably reduce the temperature of
the solution, without reducing the oxidation potential of the
solution. Phosphate ion is a known masking agent for Fe.sup.3+ and
stabilizer of H.sub.2O.sub.2; either or both of these
characteristics may be involved in the observed phenomena. In
experiments in which the peroxide concentration in solution
exceeded 1 M, phosphate was included to control the temperature of
the reaction.
[0111] 5. Storing and Dispensing the Gel Formulation
[0112] The final consideration regarding the decontaminating gel is
storage and dispensing. Ideally, the decontaminating gel is stored
in two separate reservoirs until needed. Preferably, one reservoir
contains the oxidants in a gel and the other reservoir contains the
ferrous salt in a gel. When needed, the gels are forced out of
their respective containers, into a mixing chamber, out of an
appropriate nozzle and onto the surface to be decontaminated. The
gels could be forced out either by pressurizing the reservoirs or
by pumping the gels from the reservoirs.
[0113] A possible challenge to this delivery system is stabilizing
the iron as Fe.sup.2+ and preventing oxidation to Fe.sup.3+ in a
gel formulation. One alternative includes, deoxygenating the iron
gel before storage or storing the ferrous salt as a dry material
until needed.
[0114] While the foregoing is directed to the preferred embodiment
of the present invention, other and further embodiments of the
invention may be devised without departing from the basic scope
thereof, and the scope thereof is determined by the claims which
follow.
* * * * *