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| United States Patent |
5,093,078 |
| Hollis , et al. |
March 3, 1992 |
Novel polymeric quaternary ammonium trihalides and use of
polymeric quaternary ammonium trihalides as microbicides, sanitizers and
disinfectants
Abstract
Polymeric quaternary ammonium trihalides, preferably triiodides, and use of
polymeric quaternary ammonium trihalides to inhibit the growth of microorganisms
in aquatic systems, to disinfect or sanitize surfaces and to disinfect the skin
of animals, including humans.
| Inventors: |
Hollis; C. George (Germantown, TN);
Rayudu; S. Rao (Germantown, TN) |
| Assignee: |
Buckman Laboratories International, Inc.
(Memphis, TN) |
| Appl. No.: |
553591 |
| Filed: |
July 18, 1990 |
| Current U.S. Class: |
422/16; 210/698; 210/753;
210/754; 210/755; 422/6; 422/7; 424/405; 504/155; 504/156; 504/160;
514/642; 523/122 |
| Intern'l Class: |
C23F 011/14 |
| Field of Search: |
422/6,16,7 424/78,405 71/67 523/122
525/422 514/642 210/698,753,754,755 |
References Cited [Referenced
By]
U.S. Patent Documents
| 3778476 |
Dec., 1973 |
Rembaum et al.. |
|
| 3898336 |
Aug., 1975 |
Rembaum et al.. |
|
| 4789489 |
Dec., 1988 |
Hollis et al. |
210/755. |
Primary
Examiner: McMahon; Timothy M.
Attorney, Agent or Firm: Finnegan,
Henderson, Farabow, Garrett & Dunner
Parent Case Text
This is a division of application Ser. No. 07/308,677, filed Feb. 10,
1989 now U.S. Pat. No. 4,960,590.
Claims
What is claimed is:
1. A method for inhibiting the growth of a
microorganism in an aqueous liquid susceptible to growth of said microorganism
which comprises the step of adding to said aqueous liquid an amount effective to
inhibit the growth of said microorganism of a polymeric quaternary ammonium
compound of the formula ##STR6## wherein X.sub.1, X.sub.2, X.sub.3 are each a
halogen and can all be the same halogen or different halogens;
R.sup.1
and R.sup.2, which can all be the same or different, are selected from the group
consisting of alkyl groups having from 1 to 20 carbon atoms and having either 0
or 1 hydroxyl substituent, a benzyl group, and a benzyl group bearing on the
benzene moiety one alkyl group having from 2 to 20 carbon atoms;
A is
selected from the group consisting of a divalent hydrocarbon radical containing
1 to 10 carbon atoms and also containing an oxygen atom as an ether group;
wherein A may be identical with or different from B, wherein B is defined as
follows:
B is a divalent hydrocarbon radical containing 1 to 10 carbon
atoms, said divalent hydrocarbon radical containing at least one hydroxyl group;
and
n is a whole number from 2 to 30, with the proviso that when A and B
are identical, n is a whole number from 1 to 15,
and wherein the polymer
is uncapped or capped on one or both ends with a quaternary ammonium group of
the formula ##STR7## wherein X.sub.1, X.sub.2, X.sub.3 are as defined above; and
R.sup.3, R.sup.4, R.sup.5, which can all be the same or different, are
alkyl groups having from 1 to 20 carbon atoms and having either 0 or 1 hydroxyl
substituent, or R.sup.3 and R.sup.4 taken together with the nitrogen to which
they are attached may form a saturated heterocyclic ring having from 5 to 7 ring
atoms.
2. The method of claim 1, wherein each of X.sub.1, X.sub.2, and
X.sub.3 in said polymeric quaternary ammonium compound is iodiode.
3.
The method of claim 2, wherein said effective amount is from 0.1 to 100 parts
per million of said aqueous liquid.
4. The method of claim 3, wherein
said effective amount is from 0.3 to 25 parts per million of said aqueous
liquid.
5. The method of claim 2, wherein said microorganism is a
bacterium.
6. The method of claim 5, wherein said bacterium is selected
from the group consisting of Enterobacter aerogenes, Staphylococcus aureus, and
Salmonella choleraesuis.
7. The method of claim 2, wherein said
microorganism is a fungus.
8. The method of claim 7, wherein said fungus
is Aspergillus niger.
9. The method of claim 2, wherein said
microorganism is an alga.
10. The method of claim 9, wherein said alga
is selected from the group consisting of Chlorella pyrenoidosa and Phormidi
inundatum.
11. The method of claim 2, wherein said aqueous liquid is
contained in a bathing vessel selected from the group consisting of swimming
pools, spas, and hot tubs.
12. The method of claim 2, wherein said
aqueous liquid is contained in a water cooling device.
13. The method of
claim 2, wherein said polymeric quaternary ammonium compound is
poly[oxyethylene(dimethyliminio)ethylene(dimethyliminio)ethylene di(triiodide)].
14. The method of claim 2, wherein said polymeric quaternary ammonium
compound is poly[(dimethyliminio)-2-hydroxypropylene triiodide].
15. The
method of claim 1, wherein said aqueous liquid is water used for sanitation
purposes.
16. The method of claim 15, wherein said water is toilet bowl
water.
17. A method of disinfecting a surface which comprises the step
of contacting said surface to be disinfected with an amount effective to
disinfect said surface of a polymeric quaternary ammonium compound of the
formula ##STR8## wherein X.sub.1, X.sub.2, X.sub.3 are each a halogen and can
all be the same halogen or different halogens;
R.sup.1 and R.sup.2,
which can all be the same or different, are selected from the group consisting
of alkyl groups having from 1 to 20 carbon atoms and having either 0 or 1
hydroxyl substituent, a benzyl group, and a benzyl group bearing on the benzene
moiety one alkyl group having from 2 to 20 carbon atoms;
A is selected
from the group consisting of a divalent hydrocarbon radical containing 1 to 10
carbon atoms and also containing an oxygen atom as an ether group; wherein A may
be identical with or different from B, wherein B is defined as follows:
B is a divalent hydrocarbon radical containing 1 to 10 carbon atoms,
said divalent hydrocarbon radical containing at least one hydroxyl group; and
n is a whole number from 2 to 30, with the proviso that when A and B are
identical, n is a whole number from 1 to 15,
and wherein the polymer is
uncapped or capped on one or both ends with a quaternary ammonium group of the
formula ##STR9## wherein X.sub.1, X.sub.2, and X.sub.3 are as defined above; and
R.sup.3, R.sup.4, and R.sup.5, which can all be the same or different,
are alkyl groups having from 1 to 20 carbon atoms and having either 0 or 1
hydroxyl substituent, or R.sup.3 and R.sup.4 taken together with the nitrogen to
which they are attached may from a saturated heterocyclic ring having from 5 to
7 ring atoms.
18. The method of claim 17, wherein each of X.sub.1,
X.sub.2, and X.sub.3 is said polymeric quaternary ammonium compound is iodide.
19. The method of claim 18, wherein said polymeric quaternary ammonium
compound is poly[oxyethylene(dimethyliminio)ethylene(dimethyliminio)ethylene
di(triiodide)].
20. The method of claim 18, wherein said polymeric
quaternary ammonium compound is poly[(dimethyliminio)-2-hydroxypropylene
triiodide].
21. A method of disinfecting the skin of an animal which
comprises the step of contacting said skin to be disinfected with an amount
effective to disinfect said skin of a polymeric quaternary ammonium compound of
the formula ##STR10## wherein X.sub.1, X.sub.2, X.sub.3 are each a halogen and
can all be the same halogen or different halogens;
R.sup.1 and R.sup.2,
which can all be the same or different, are selected from the group consisting
of alkyl groups having from 1 to 20 carbon atoms and having either 0 or 1
hydroxyl substituent, a benzyl group, and a benzyl group bearing on the benzene
moiety one alkyl group having from 2 to 20 carbon atoms;
A is selected
from the group consisting of a divalent hydrocarbon radical containing 1 to 10
carbon atoms and also containing an oxygen atom as an ether group; wherein A may
be identical with or different from B, wherein B is defined as follows:
B is a divalent hydrocarbon radical containing 1 to 10 carbon atoms,
said divalent hydrocarbon radical containing at least one hydroxyl group; and
n is a whole number from 2 to 30, with the proviso that when A and B are
identical, n is a whole number from 1 to 15,
and wherein the polymer is
uncapped or capped on one or both ends with a quaternary ammonium group of the
formula ##STR11## wherein X.sub.1, X.sub.2, X.sub.3 are as defined above; and
R.sup.3, R.sup.4, R.sup.5, which can all be the same or different, are
alkyl groups having from 1 to 20 carbon atoms and having either 0 or 1 hydroxyl
substituent, or R.sup.3 and R.sup.4 taken together with the nitrogen to which
they are attached may from a saturated heterocyclic ring having from 5 to 7 ring
atoms.
22. The method of claim 21, wherein said animal is a human.
Description
This invention encompasses polymeric quaternary ammonium trihalides,
particularly triiodides, and their use as general microbicides, particularly as
bactericides and fungicides, for aqueous systems, as surface, particularly hard
surface, disinfectants or sanitizers, and as disinfectants for animal skin,
including the skin of humans.
BACKGROUND OF THE INVENTION
Polymeric quaternary ammonium compounds (also known as ionene polymers
or polymeric quats) containing chlorides and bromides as anions have been shown
to be aquatic bactericides and algicides (U.S. Pat. Nos. 3,874,870, 3,931,319,
4,027,202, and 4,581,058). In fact, Busan.RTM. 77 polymer, an ionene chloride,
is sold commerically as an algicide and bactericide for various aquatic systems,
such as water cooling devices, swimming pools, and fresh water holding tanks.
However, these polymeric quats could stand improvement. In particular, it would
be significant to develop polymeric quats that are even better fungicides, and
also are faster in killing bacteria.
The present invention can
constitute such an improvement an describes compounds, some of which are novel,
which contain trihalide as the counter ion to the quaternary nitrogens in the
polymer chain and which are useful as aquatic microbicides, disinfectants for
human skin, and surface disinfectants or sanitizers. Representative trihalides
useful in the present invention include Br.sub.3 -, I.sub.3 -, ClI.sub.2 -,
ClBr.sub.2 - and Br.sub.2 - is the preferred trihalide.
U.S. Pat. Nos.
3,778,476 and 3,898,336 describe the preparation of some of these compounds. The
disclosure of these patents is specifically incorporated by reference herein.
The compounds of these two patents are proposed therein for use in coating
substrates to provide an antibacterial layer for an application such as surgical
sutures. The present invention is the method of using ionene trihalides to
disinfect or sanitize surfaces and provide microorganism control in aquatic
systems and also includes some novel trihalide compounds.
SUMMARY OF THE
INVENTION
The inventors have discovered a new method of inhibiting the
growth of a microorganism in aquatic systems susceptible to the growth of such
microorganism, a new method of disinfecting or sanitizing surfaces and a new
method of disinfecting skin. The method uses ionene trihalides, preferably
ionene triiodides, which can prevent the proliferation of microorganisms, such
as bacteria, fungi, and algae, in various systems which contain or move water.
In particular, ionene trihalides can kill bacteria and fungi very
quickly and can be functional as hard surface disinfectants used in hospitals,
food handling facilities, and the like. The ionene trihalides can specifically
be used to sanitize toilets and to disinfect the skin of humans and other
animals.
The present invention also provides a composition of matter
which is a polymeric quaternary ammonium compound having the formula ##STR1##
wherein X.sub.1, X.sub.2 and X.sub.3 are each a halogen and can all be the same
halogen or different halogens and wherein R.sup.1 and R.sup.2, which can all be
the same or different, are selected from the group consisting of alkyl groups
having from 1 to 20 carbon atoms and having either 0 or 1 hydroxyl substituent,
a benzyl group, and a benzyl group bearing on the benzene moiety one alkyl group
having from 2 to 20 carbon atoms; A is selected from the group consisting of a
divalent hydrocarbon radical containing 1 to 10 carbon atoms, preferably an
alkylene radical, and a divalent hydrocarbon radical containing 1 to 10 carbon
atoms and also containing an oxygen atom as an ether group; B is a divalent
hydrocarbon radical containing 1 to 10 carbon atoms, preferably an alkylene,
aryl, arylalkylene or alkylenearylakylene radical, the hydrocarbon radical being
substituted by at least one substituent selected from the group consisting of a
hydroxyl group and a substituent substituted by at least one hydroxyl group; n
is a whole number from 2 to 30 with the proviso that if A and B are identical,
then n is a whole number from 1 to 15; and wherein the polymer may be capped on
one or both ends with a quaternary ammonium group ##STR2## wherein X.sub.1,
X.sub.2 and X.sub.3 are as defined above and wherein R.sup.3, R.sup.4, and
R.sup.5, which can all be same or different, are alkyl groups having from 1 to
20 carbon atoms and having either 0 or 1 hydroxyl substituent, or R.sup.3 and
R.sup.4 taken together with the nitrogen to which they are attached may form a
saturated heterocyclic ring having from 5 to 7 ring atoms.
Substituent A
may be substituted or unsubstituted. Preferably, A is substituted by at least
one substituent selected from the group consisting of a hydroxyl group and a
substituent substituted by at least one hydroxyl group.
Preferred
substituents for both the A and B moieties, which can be identical or different,
include C.sub.n H.sub.2n OH wherein n ranges from 1 to 10, and more preferably
CH.sub.2 OH, and also hydroxyaryl, and more preferably hydroxyphenyl.
DETAILED DESCRIPTION OF THE INVENTION
Ionene polymers belong to
a well-known class of compounds, which together with methods for their
preparation are described in U.S. Pat. Nos. 3,874,870, 3,931,319, 4,025,627,
4,027,020, and 4,506,081. The trihalides of ionenes, such as the triiodides in
particular, can be prepared by replacing the halogen, preferably chloride or
bromide, with trihalide anion, as described in U.S. Pat. No. 3,778,476.
For example, a triiodide solution is prepared by mixing iodine and an
alkali metal iodide, preferably potassium or sodium iodide, in water. On adding
a solution of polymeric quaternary ammonium chloride or bromide to this
triiodide solution, a dark solid precipitates. After decanting the aqueous
layer, the triiodide compound is obtained. The triiodide compound can be used in
the solid form or solubilized in acetone or some other suitable polar organic
solvent or combination of solvents to yield an effective formulation.
Formulations of ionene trihalide and in particular, ionene triiodide,
can be added to various water systems to control the growth of undesirable
microorganisms, including fungi. The effectiveness against fungi that can be
obtained is surprising in view of the lack of efficacy of conventional ionenes,
i.e., those having single halogen ions as the counter ions to the positive
charges, against fungi.
Ionene trihalides, such as the triiodides, can
also be used to disinfect or sanitize surfaces. The time required to completely
kill bacteria on a hard surface can be much less for the trihalide salt than
that for conventional halide salts.
The solid form of the triiodide can
be added to water systems, such as cooling towers or swimming pools, to provide
a continuous release microorganism control agent.
The ionene trihalides
of this invention that are novel differ from those described in the prior art,
such as U.S. Pat. Nos. 3,778,476 and 3,898,336, because the B substituent
described above contains at least one pendant hydroxyl group, i.e., at least one
hydroxyl group substituent attached directly to the main polymer chain (the
divalent hydrocarbon radical) or at least one substituent (pendant group) itself
substituted by at least one hydroxyl group, the substitutent being attached
directly to the divalent hydrocarbon radical. This difference improves the
solubility in water and provides an advantage when used in aquatic systems.
Preferred trihalides are poly[(dimethylimini )-2-hydroxy-propylene
triiodide] of the formula ##STR3## wherein A and B are identical and n is from 1
to 15; poly[oxyethylene(dimethyliminio)hydroxypropylene(dimethyl-iminio)ethylene
di(triiodide)] of the formula ##STR4## wherein n is from 2 to 30; and
poly[2-hydroxyethylene(dimethyliminio)ethylene(dimethyl-iminio)-methylene
di(triiodide)] of the formula ##STR5## wherein n is from 2 to 30.
The
invention will be further clarified by the following examples, which are
intended to be merely illustrative of the present invention.
EXAMPLE 1
Preparation of
poly[oxyethylene(dimethyliminio)ethylene(di-methyliminio)-ethylene
di(triiodide)] (Compound 1)
A solution of 12.7 g (0.05 mole) of iodine
and 20.0 g (0.12 mole) of potassium iodide in 1 liter of water was prepared. To
the above vigorously-stirred solution were added dropwise 21.6 g (0.05 molar
equivalents of chloride ion) of
poly[oxyethylene-(dimethyliminio)ethylene-(dimethyliminio)ethylene dichloride]
(60% aqueous solution available commercially as Busan.RTM. 77 polymer). During
this addition, a dark brown solid precipitated out of the solution, and the
amount of solid increased with the increasing amount of polymer dichloride that
was added. After the addition was complete, the reaction mixture was stirred at
room temperature for an additional two hours. Most of the aqueous layer was
decanted and the precipitate was filtered and collected. A 73.7% yield (35.0 g)
of this dark brown solid was obtained. An elemental analysis (in duplicate) of
the solid showed it to be
poly[oxyethylene(dimethyliminio)ethylene-(dimethyliminio)ethylene
di(triiodide)]. The results are given in Table 1.
TABLE 1
______________________________________
Element % Calculated
% Found (1)
% Found (2)
______________________________________
C 12.63 13.14 13.20
H 2.53 2.64 2.55
I 80.21 79.23 79.14
N 2.95 3.08 3.04
______________________________________
The solubility of this compound was determined by stirring 1 gram
in 1 liter of deionized water for 2 hours. Supernatant solution was analyzed for
quaternary ammonium salts using the bromophenol blue titration method and for
iodide using a selective ion electrode. The amount of the dissolved polymeric
quaternary ammonium triiodide was found to be 183 ppm, which is well above the
effective level in water as subsequent examples show. This compound can be
formulated at 5% in N-methyl-pyrollidone using Atlox 3409 surfactant.
EXAMPLE 2
Preparation of
poly[(dimethyliminio)-2-hydroxypropylene triiodide] (Compound 2).
The
procedure described in Example 1 was followed using
poly[(dimethyliminio)-2-hydrox chloride], a product commercially available as
Busan.RTM. 1055 polymer.
Elemental analysis of the product gave the
expected results, shown in Table 2.
TABLE 2
______________________________________
Element % Calculated
% Found
______________________________________
C 12.42 13.00
H 2.48 2.67
I 78.88 77.58
N 2.89 3.04
______________________________________
EXAMPLE 3
Effectiveness of Compound 1 and Compound 2
against bacteria
The effectiveness of the Compounds 1 and 2 prepared in
Examples 1 and 2 was determined against Enterobacter aerogenes at ph 8.0 using
the method described in U.S. Pat. No. 2,881,070 with the modification described
in Example 22 of U.S. Pat. No. 4,054,542. Effectiveness of each polymer was
determined at various contact times. The results are given in Table 3.
In comparison to these results, the dichloride used as the starting
material in Example 1, Busan.RTM. 77 polymer, has an MIC of 10 ppm for 8 hours
contact time and 20 ppm for 4 hours contact time.
TABLE 3
______________________________________
Minimum Inhibitory Concentration (MIC) of two triiodinated
polymers to produce 90% kill of Enterobacter aerogenes in a basal
salts solution at pH 8.0 after multiple contact times
Contact Time MIC in parts per million
(hours) Compound 1 Compound 2
______________________________________
2 0.3 2
4 0.3 2
6 0.3 2
8 0.3 2
24 0.3 2
______________________________________
EXAMPLE 4
Disinfectant effectiveness of Compound 1 and
Compound b 2.
In this example, the effectiveness of the compounds
prepared in Examples 1 and 2 was determined against Staphylococcus aureus and
Salmonella choleraesuis using the A.O.A.C. Use-Dilution test described in the
Official Methods of Analysis (1984) 14th Ed., AOAC, Washington, DC, Secs.
4.007-4.0111. The results are given in Table 4.
TABLE 4
______________________________________
Maximum dilution providing kill in
10 of 10 replicates in 10 min. vs.
Test material
Staphylococcus aureus
Salmonella choleraesuis
______________________________________
Compound 1
1:1000 1:1000
Compound 2
1:2500 1:2500
______________________________________
EXAMPLE 5
Zone Inhibition Study with Compounds 1 and 2
The inhibitory properties of the two ionene triiodides prepared in
Examples 1 and 2 were assayed against Enterobacter aerogenes and Staphylococcus
aureus using a zone of inhibition technique. In this assay, nutrient agar was
inoculated with E. aerogenes and poured into a sterile petri dish. When the agar
was solidified, a measured disc of the solid test compound was placed on the
surface of the inoculated agar. Following incubation, the clear zone surrounding
the measured disc was measured. This procedure was repeated with S. aureus.
Inoculated agar plates to which no test compound was added were included as
controls. The results are shown in Table 5.
TABLE 5
______________________________________
Zone of Inhibition of Enterobacter aerogenes and Staphylococcus
aureus by Compounds 1 and 2 after 24 hours incubation.
Zone of inhibition in millimeters vs.
Test material E. aerogenes
S. aureus
______________________________________
Control 0 0
Compound 1 7 5
Compound 2 Complete Complete
______________________________________
EXAMPLE 6
Effectiveness of Compounds 1 and 2 against
fungi.
The effectiveness of the compounds prepared in Examples 1 and 2
against the fungus Aspergillus niger was determined in a mineral salts medium.
The medium is composed of the following:
______________________________________
Glucose 10.0 g
Ammonium nitrate 3.0 g
Potassium phosphate (K.sub.2 PO.sub.4)
1.0 g
Potassium chloride 0.25 g
Magnesium sulfate 0.25 g
Tween 80 0.5 g
HCl-Trizma buffer 6.0 g
Deionized water 1000 ml
______________________________________
Forty-gram portions of the medium are added to 250-ml Erlenmeyer
flasks fitted with loose metal caps and then sterilized. The following
substances are then added to each bottle in the order listed:
1. Sterile
mineral salts solution as required in each individual case to bring the total
weight of the contents of each flask to 50 g, after allowing for all subsequent
additions specified hereinafter, including inoculation with the aqueous
suspension of spores.
2. Solution of toxicant to be evaluated in such
individual volumes to give the concentration desired in the test; the amount is
computed in parts per million by weight. Duplicate controls containing no
toxicant are used.
3. Inoculum consisting of 1 ml of an aqueous
suspension of spores and/or mycelial fragments of the test organism.
After the inoculant suspensions of the test fungus have been added, the
flasks are incubated at 30 .+-. 1.degree. C. for a period adequate for growth in
the controls. The customary period of observation is 14 days. Growth is recorded
at 7 days and 14 days on the basis of the following key:
4 = excellent
growth
3 = good
2 = poor
1 = very poor, scant,
questionable
0 = no growth
A toxicant is considered an effective
fungicide if it scores 0 (no growth) at the recommended use concentration at the
14-day observation period. The results of the test with Compound 1 and Compound
2 are given in Table 6. In comparison, the chloride analog of Compound 1,
Busan.RTM. 77 polymer, will not control A. niger at 1000 ppm, the highest level
tested.
TABLE 6
______________________________________
Inhibition of Aspergillus niger by two triiodinated polymers
after 14 days.
Concentration
Test material
in ppm Growth Rating
______________________________________
Compound 1 1 4
5 4
25 0
Compound 2 1 4
5 4
25 0
______________________________________
EXAMPLE 7
Effectiveness of Compounds 1 and 2 against
algae.
The growth inhibiting activity of the compounds made in Examples
1 and 2 was evaluated in Difco Algae Broth, the content of which was as follows:
______________________________________
Compound Grams per liter
______________________________________
Sodium nitrate 1.000
Ammonium chloride
0.050
Calcium chloride 0.058
Magnesium sulfate
0.513
Dipotassium phosphate
0.250
Ferric chloride 0.003
______________________________________
Forty-gram portions of the algae medium were added to 250 ml Pyrex
Erlenmeyer flasks fitted with loose metal caps and then sterilized. Each of the
following substances was then added to the flasks in the order listed:
1. Sterile algae medium as required to bring the total weight of the
contents of each flask to 50 grams, after allowing for all subsequent additions
specified hereinafter.
2. Solution of toxicant or control agent to be
evaluated in each test, to give the concentration desired in parts per million
by weight.
3. Chlorella pyrenoidosa and Phormidium inundatum in amounts
sufficient to give excellent growth in the controls after 14 days. This was
achieved by adding 1 milliliter of a 14 day old culture having luxuriant growth.
The Chlorella pyrenoidosa culture was obtained from American Type Culture
Collection No. 7516; Phormidium inundatum, Wisconsin No. 1093, was obtained from
the University of Washington.
After the inoculum of the test algae was
added, the flasks were incubated at a temperature of 28 .+-. 2.degree. C. under
fluorescent illumination of 250 foot-candle intensity (8 hours light, 16 hours
darkness) for a period adequate for growth in the controls (those portions of
medium which contained no toxicant). Observations of growth were made at 7 day
intervals on the basis of the following key:
4 = excellent growth
3 = good
2 = poor
1 = very poor, scant, questionable
0 = no growth
The results are given in Table 7.
TABLE 7
______________________________________
Inhibition of algae by Compounds 1 and 2.
Concentration
Organism in ppm Compound 1 Compound 2
______________________________________
Chlorella
1 1 3
pyrenoidosa
5 0 0
10 0 0
25 0 0
Phormidium
1 1 1
inundatum
5 0 0
10 0 0
25 0 0
______________________________________
* * * * *
