Disinfectant composition and a disinfection method using the same

This invention provides a disinfectant composition which is suited to the disinfection of confined spaces such as the interior of an ambulance or the like. It is prepared extemporaneously by blending a highly concentrated alcohol with glutaraldehyde and a buffer solution such as an aqueous solution of diethanolamine. This composition containing 65 to 80% of alcohol and 2 to 4% of glutaraldehyde exhibits a strong and lasting disinfectant effect. The invention further provides a method for space disinfection which comprises atomizing and spraying this disinfectant composition by means of a high-pressure gas such as pressurized carbon dioxide gas.

BACKGROUND ART 
1. Technical Field 
The present invention relates to a disinfectant composition which can be 
used advantageously in the disinfection of generally confined areas, for 
example within buildings and vehicles such as buses, ambulances, etc., and 
to a disinfection method using said composition. 
2. Background Art 
In the disinfection of a confined area such as the interior of an 
ambulance, routine general cleaning must be followed by a time-consuming 
disinfection work which includes wiping with a swab and disinfectant 
solution. 
The ambulance, for instance, must be maintained at least at a certain level 
of cleanliness because its function is to transport patients while they 
are given initial treatment, and for this purpose, routine disinfection is 
an important procedure. It is generally acknowledged that the mean viable 
count of coliform bacteria, staphylococci, general bacteria, fungi and so 
on should not be more than 10 colony-forming units (CFU/10 cm.sup.2) and 
preferably not more than 5 CFU/10 cm.sup.2 [Kyukyu Iryo no Kiso to Jissai: 
1 Kyukyu Gyomu to Kyukyu Iryo] (The Fundamentals and Practice of Emergency 
Medicine: 1 Emergency Management and Emergency Medicine, edited by the 
Emergency Department of the Metropolitan Fire Board of Tokyo, published by 
Joho Kaihatsu Kenkyusho). 
The conventional disinfection procedure comprises using an aqueous dilution 
of a certain disinfectant such as cresol by manual swab cleaning or spray 
cleaning with the aid of a hand-operated or electrically-driven sprayer. 
In some extraordinary or unavoidable cases, a disinfectant solution based 
on glutaraldehyde, which is known to be an effective 
sterilant/disinfectant, has been employed. Thus, for example, glutaral is 
diluted with water to a concentration of about 1 to 2 percent and applied 
by swab cleaning. 
However, the conventional disinfection procedure is not only time-consuming 
but also inadequate in that all nooks and corners can hardly be reached 
for thorough disinfection. Moreover, as the diluted disinfectant solution 
is applied by spraying, the water remains on the treated surface and the 
desired disinfecting effect is not obtained in corner areas so that no 
satisfactory result is accomplished. 
In addition, when said glutaraldehyde is used for swab cleaning, the 
irritating and pungent odor persists for a long time. Thus, the odor is in 
the air for as long as 12 to 24 hours. 
It is an object of the present invention to provide a disinfectant 
composition which can be used advantageously in the disinfection of 
confined areas such as within the ambulance under all circumstances, is 
capable of providing a very high disinfecting effect, can be easily 
prepared in the field, and does not give off an irritating odor. 
It is another object of the invention to provide a disinfection method by 
which said disinfectant composition can be applied uniformly to all the 
nooks and corners of such confined spaces. 
SUMMARY OF THE INVENTION 
The disinfectant composition provided by the present invention for solving 
the above-mentioned problems is characterized in that it is 
extemporaneously prepared by blending a highly concentrated alcohol with 
glutaraldehyde and a buffer solution such as an aqueous solution of 
diethanolamine to provide a composition containing 65 to 80% of alcohol 
and 2 to 4% of glutaraldehyde. 
Preferably, the above composition is prepared by blending a basal mixture 
of said highly concentrated alcohol and a perfume with 10 to 20 volume 
percent of a 20% (aqueous) solution of glutaraldehyde and 3 to 7 volume 
percent of a buffer solution such as a 1.0 to 2.0% aqueous solution of 
diethanolamine. 
Thus, since glutaraldehyde has an irritating odor which requires forced 
ventilation with a fan blower or the like following each cleaning job, a 
perfume is preferably added as mentioned above for masking this unpleasant 
odor. 
Moreover, if the concentration of glutaraldehyde used in this blending is 
less than 2%, the disinfectant effect is markedly compromised, while the 
use of glutaraldehyde over the concentration of 4% is undesirable, for it 
then gives off an intense irritating odor during cleaning and causes a 
prolonged carryover of the odor after cleaning. 
The concentration of alcohol in the disinfectant composition is preferably 
in the above-mentioned range of 65 to 80 percent, for both an excess and a 
shortage of alcohol result in a poor disinfectant effect. 
The highly concentrated alcohol mentioned above may be a relatively 
volatile and biocidally active concentrated alcohol such as ethanol, 
methanol or of at least 80% concentration isopropyl alcohol, or the 
corresponding alcohol denatured with some denaturants. For example, there 
may be mentioned the denatured alcohols obtainable by blending highly 
concentrated ethanol with denaturants such as methanol, isopropyl alcohol, 
etc. or, more specifically the so-called methanol-denatured alcohol 
prepared by adding 5 kg of 95% methanol to each 200 l of 95% ethanol. 
Since the use of ethanol alone is costly, it is preferable to use a 
denatured alcohol such as the above-mentioned methanol-denatured alcohol. 
Isopropyl alcohol of 80 to 90 percent concentration can also be used with 
advantage from the standpoint of safety. 
With the above disinfectant composition, excellent sterilizing and 
disinfecting effects can be obtained by virtue of the disinfectant 
glutaraldehyde. Thus, glutaraldehyde is a chemically synthesized substance 
and has been shown to kill various bacteria, tubercle bacilli, fungi, 
bacterial spores, and viruses. The use of a solution of this 
glutaraldehyde diluted with alcohol produces a sufficient sterilizing and 
disinfecting effect. 
Particularly because said basal concentrated alcohol is used as a diluent 
for glutaraldehyde, the glutaraldehyde can be well diluted and, in 
addition, the concentrated alcohol itself exerts an excellent sterilizing 
and disinfecting effect so that a sufficient effect can be obtained even 
with a moderate amount of glutaraldehyde. 
Furthermore, as a buffer solution is included in the disinfectant 
composition, the pH of the application solution can be maintained at about 
7.5 to 8.5 so that the disinfectant effect may last for about 10 days 
after application. Furthermore, the incorporation of the perfume as a 
masking agent is useful in cancelling the irritating odor of 
glutaraldehyde. 
Moreover, since the disinfectant composition of the invention can be easily 
provided by blending said base alcohol, such as concentrated ethanol, 
isopropyl alcohol or a denatured alcohol prepared by using a methanol or 
the like as a denaturant, which may be optionally perfumed as mentioned 
above, with a commercial 20% solution of glutaraldehyde and a buffer 
solution such as an aqueous solution of diethanolamine, it can be easily 
prepared in the field and applied as it is. 
The disinfection method using the above-mentioned disinfectant composition 
in accordance with the present invention is characterized in that a 
disinfectant composition prepared by the above blending procedure is 
comminuted and sprayed in finely divided form with the aid of a 
pressurized gas. Generally the above disinfectant composition is applied 
by spraying about 70 to 80 ml per 25 m.sup.3. 
With regard to the pressurized gas mentioned above, it is preferable to 
utilize the pressure of vaporization of liquefied carbon dioxide gas. In 
this case, the disinfectant composition must be sprayed in a mixing ratio 
well below the dust explosion limit of the alcohol with respect to carbon 
dioxide gas. The mixing ratio is, namely, about 0.001 volume part (%) of 
the disinfectant composition to 100 volume parts of carbon dioxide gas. 
Thus, the above ratio is recommended in view of the fact that the lower 
explosion limit of alcohol in the air is 3.3 volume percent. 
The liquefied carbon dioxide gas is sprayed at a gauge pressure of about 
3-6 kg/cm.sup.2. 
When sprayed in this manner, the above-mentioned disinfectant composition 
is atomized in the form of ultramicro particles and can diffuse uniformly 
into all the nooks and corners throughout the space sprayed therewith. The 
disinfectant effect of glutaraldehyde can be produced promptly. 
Particularly when carbon dioxide gas is used, there is no possibility of 
chemical reactions with the active ingredient mentioned above, hence there 
is no fear of changes in properties of the composition, and the 
glutaraldehyde and highly concentrated alcohol in the disinfectant 
composition produce an excellent synergistic disinfectant effect. 
Furthermore, when carbon dioxide gas is used as a high-pressure gas, the 
precipitation of disinfectant particles sprayed into the air can be 
promoted through the specific gravity effect of carbon dioxide gas. 
Moreover, the use of a large quantity of carbon dioxide gas can fully 
eliminate the possibility of ignition or explosion in spite of the use of 
alcohol as the base of the composition. Thus the composition can be 
sprayed safely even in places where there is heat of fire. 
Therefore, said composition can be used to disinfect confined areas such as 
the interior of an ambulance car efficiently and reliably within a short 
period of time.