Abstract:
A sterilized chemical composition is stored in a sterile environment for a prolonged period of time, hermetically sealed in successive enclosures and a shipping enclosure. The third sealing layer is removed prior to entering a storage area. The second layer is removed prior to taking the container to the sterile environment. The storage area may also be sterile. The innermost container may be an aerosol container and the composition a disinfectant liquid such as alcohol. The entire shipping enclosure and contents is preferably sterilized with gamma radiation.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    This invention pertains to methods of optimizing the sterilization process for chemical compositions and to allow extended shelf life for sterilized chemical compositions on-site for operational use. In particular, the subject invention concept is directed to a method of sterilizing chemical compositions utilizing irradiation techniques which allow for the chemical composition being sterilized to be maintained within containers for extended periods of time with the assurance that the contents are maintained in a sterilized state. Still further, this invention concept is directed to an improved sterilization method for chemical compositions in general and particularly for isopropyl alcohol used in decontamination procedures. More particularly, this invention is directed to a method where chemical compositions within containers are hermetically sealed to provide a relatively contaminant free outer surface subsequent to a gamma irradiation process for sterilization of the contents of the container being sealed. Still further, this invention directs itself to a method wherein a hermetically sealed container is further hermetically sealed with a second sealing layer which in itself is formed around and encases the first sealing layer and container. More in particular, this invention directs itself to a method of optimizing the sterilization procedure for a chemical composition by providing a third sealing layer around one or a plurality of double sealed containers prior to a gamma ray irradiation process. Still further, this invention provides for a series of processing steps whereby a carton containing sterilized containers may be shipped to a relatively contaminated area and removed to a relatively contamination free area while still maintaining a double hermetic seal around the sterilized containers.  
           [0003]    2. Prior Art  
           [0004]    Sterilization procedures for chemical compositions are well known in the art. However, increasing statutory demands call for extended, complicated and time-consuming sterilization procedures which require detailed cataloguing and analysis associated with the assurance that a sterilized composition is being maintained in a sterilized state over a period of time so that such can be assured of being sterilized when operationally used.  
           [0005]    In some prior art techniques, a single covering layer is used for sealing irradiated chemical compositions. However, such sterilized chemical compositions lose their sterilization ratings over an extended period of time due to the fact that even when on the shelf of a clean room, such are impinged with various microorganisms and contamination particulates. Thus, shelf lives had to be catalogued with the result that there was extended periods of time used in documenting as well as analyzing sterilization procedures in maintaining the sterilization requirements. Still further, in other prior art systems, the contents of a container were irradiated however, no sealing layers were added which even further decreased the sterilization maintenance of the contained chemical compositions.  
         SUMMARY OF THE INVENTION  
         [0006]    This invention is directed to a method of sterilization which includes the step of providing a chemical composition to be sterilized. The chemical composition is then charged into a container and the container is encased within a first sealing layer forming a single layer sealed container enclosure. The single layer sealed container enclosure is then encased within a second sealing layer forming a second layer sealed container enclosure. Both the first and second sealing layers provide for hermetic sealing and the entire second layer sealed container enclosure is inserted into a carton which is lined with a third sealing layer. The third sealing layer is then closed and the entire carton is irradiated at a predetermined radiation level for sterilizing the chemical composition contained within the original container.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    [0007]FIG. 1 is a block diagram showing the method steps for the method of sterilization as herein described;  
         [0008]    [0008]FIG. 2 is a cross-sectional view of a first sealing layer being placed over a chemical container;  
         [0009]    [0009]FIG. 3 is a cross-sectional view of a second sealing layer encasing the first sealing layer and forming a second layer sealed container enclosure;  
         [0010]    [0010]FIG. 4 is a cross-sectional view of a carton having a third sealing layer lining for insertion of the second layer sealed container enclosure; and,  
         [0011]    [0011]FIG. 5 is a perspective view of a closed carton member being irradiated in a plurality of planes.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0012]    Referring now to FIGS.  1 - 5 , there is shown a method of sterilization for maintaining chemical compositions in a sterilized state over an extended period of time. The subject invention concept is directed to both the combined sterilization process for chemical compositions in combination with the maintenance of the sterilization state for the chemical compositions over a long period of time in order that the user may safely use the sterilized compositions at their discretion with the assurance that the chemical composition remains in a sterilized state. Thus, the problems associated with sterilization are two-fold in nature where the initial problem of sterilization is only one portion of the maintenance of the sterilization concept of the subject method. In general, chemical compositions are sterilized and then shipped in cartons such as cardboard containers with a plastic lining to protect the sterilized compositions maintained in their own containers within the cardboard cartons. The cardboard cartons are generally shipped by normal shipping procedures such as trucks, rail cars, or air transportation. The cartons are brought to the site where the sterilized containers are to be used and in general, procedures have been worked out where the containers and their plastic enclosure are brought internal to the work place while the container which may by then have various contaminating microbes or other particulates are left external to the workplace. The workplace then may store the chemical composition containers in a clean room or other type of room which in itself is designated as a room relatively free of contaminants but such clean rooms also have microbes and various other contaminating particulates in the atmosphere. Thus, a shelf life must be designated for such sterilized chemical composition containers even when used in a clean room type of atmosphere.  
         [0013]    In order to solve the problem of shelf life, the subject invention concept&#39;s method provides for a series of steps which allow the sterilized chemical compositions within their own containers to be maintained over extended periods of time without a shelf life dependent on the sterilized state being designated nor being important to the maintenance of the chemical composition sterilization.  
         [0014]    The use of the subject invention concept method for sterilization of chemical compositions has great use in the pharmaceutical industry. The pharmaceutical industry uses a large amount of alcohol for decontamination since it does kill various organisms. Thus, the pharmaceutical industry demands sterile alcohol and in particular the chemical compositions as herein described and detailed direct themselves to alcohol compositions and particularly to isopropyl alcohol used extensively in the pharmaceutical industry.  
         [0015]    Referring now to FIG. 1 which provides a block diagram associated with the overall method of sterilization as herein described, the chemical composition is obtained from a vendor and assayed in block  10  wherein it is determined that a proper formulation of the chemical composition has been received. In the case of isopropyl alcohol many different types of composition formulations may be required under varying statutory laws associated with sterilization in different environments. In general, if an alcohol such as isopropyl alcohol is used it may be assayed or measured to provide predetermined compositions or formulations, two of the standards being 70% isopropyl alcohol with 30% water or 91% isopropyl alcohol and 9% water by volume.  
         [0016]    The analyzed and measured chemical composition is then passed to a filter mechanism represented by block  20  in FIG. 1. The filter shown in block  12  may be a standard mechanical filter such as a cartridge filter having a predetermined filtering range such as a 0.22 micron filter to allow removal of particulate matter greater than the filter size. In effect, filter  12  removes residual particulates that may be in the chemical composition and at the size range of 0.22 microns even removes bacteria that may be in the chemical composition liquid. Thus, certain bacteria and spores as well as other particulate contaminants are removed during this phase of the overall method of sterilization.  
         [0017]    The chemical composition is brought from the mechanical filter  12  to block  14  which is a test for particulate or microscopic matter. Testing is done in accordance with Test Number 788 dictated in the USP XXII Journal for determination of particulate matter contained within various chemical compositions. The test procedure is well known and used as a standard in the chemical industry where the composition is mixed in a container and the chemical composition has a vacuum applied thereto to allow passage into and through a filter. A section of the filter assembly is removed from the container while maintaining the vacuum and the filter is then placed in a Petri slide. The filter is dried with the cover of the Petri slide slightly open and particles on the filter are counted. Such testing is well known in the art and determines whether particulate matter of predetermined sizes has been removed from the chemical composition.  
         [0018]    Once the particulate material testing in block  14  has been completed, the chemical composition is then brought to a secondary concentration test block  16  where the concentration of the chemical composition is once again analyzed to make sure that the proper chemical composition formulation has been maintained. Secondary concentration test block  16  may be a standard well known concentration test as was provided in block  10 . Once the chemical composition has passed through secondary concentration test block system  16 , the chemical composition is then ready for packaging and has been assured of a proper formulation composition as well as an assurance to the fact that predetermined particulate sizes have been removed from the overall chemical composition.  
         [0019]    Thus, in the flow blocks associated with FIG. 1, after passage through the initial concentration or assaying test block  10 , mechanical filter  12 , testing for microscopic material  14  and insertion into the secondary concentration test block  16 , there has been provided a chemical composition of predetermined concentration which is to be sterilized in accordance with the invention concept steps of the subject method.  
         [0020]    After the secondary concentration testing as shown in block  16  is completed, container  20  shown in FIGS. 2 and 3 is filled with the chemical composition as provided in block  18  of FIG. 1. Chemical composition container  20  may be a standard aerosol can or alternatively may be a container with a cap closure. When using isopropyl alcohol as the chemical composition, such is generally inserted under pressure with an inert element such as nitrogen or another chemical formulation acting as the propellant into an aerosol can type chemical composition container  20 . Once the chemical composition is inserted into chemical composition container  20  as shown in block  18 , a nozzle may be mounted at one end with differing nozzle pattern generating systems being used dependent upon what is necessary for a particular decontamination operation. Such type of closure whether it be a nozzle arrangement system or a cap closure is not important to the inventive concept as herein described with the exception that such provide egress of the chemical composition appropriate for a particular decontamination operation. Once the filling composition container  20  has been filled, the operational phase moves to block diagram  22  of FIG. 1 where container  20  is encased within first sealing layer  24  forming a single layer sealed container enclosure  26 .  
         [0021]    First layer  24  seen in FIGS. 2 and 3, may be formed of a plastic composition of the closed cell type and in particular may be formed of a polyethylene composition. Once chemical composition container  20  has been encased by first layer  24 , first layer  24  may be heat sealed to form a substantially hermetic seal for chemical composition container  20  as shown in FIG. 2. At this stage of the process steps, single layer sealed enclosure  26  has been created and is moved to block  28  of FIG. 1 where second sealing layer  30  encases single layer sealed enclosure  26  to form second layer sealed container enclosure  32 . Second sealing layer  30  may also be formed of a plastic composition of the closed cell type and in particular may also be a polyethylene composition similar to first layer  24 . Second sealing layer  30  may then be also heat sealed to provide a hermetically sealed second layer sealed container enclosure  32  as shown in FIG. 3.  
         [0022]    Once second sealing layer  30  has been applied and heat sealed to establish second layer sealed container enclosure  32 , the enclosure  32  is then inserted into plastic lined carton  36  as shown in FIG. 4 and depicted in flow block  34  of FIG. 1. Carton  36  may be a cardboard type container adaptable for transportation and associated shipping to the operations site. Additionally, there is provided third sealing layer  38  as shown in FIG. 4, which is a lining for carton  36 . Third sealing layer  38  may once again be formed of a plastic type composition of the closed cell type which may also be a polyethylene bag-like element. Third sealing layer  38  lines the internal walls of carton  36  in order to provide an insert for one or a plurality of second layer sealed container enclosures  32  therein. Third sealing layer  38  may then be closed through tying or some like closure mechanism at an upper section  40  and in this manner the entire second layer sealed container enclosure  32  is then contained therein. Finally, carton  36  may be closed in the standard manner of flap closures for container members.  
         [0023]    Once the second layer sealed container enclosure has been inserted into lined carton  36  as shown in block  34  of FIG. 1, carton  36  is then brought to block  42  for carton irradiation processes. The carton irradiation step as depicted in block  42  of FIG. 1 may be a gamma irradiation system where the decay of each atom of cobalt  60  generates a pair of photons of gamma radiation having predetermined energies as well as a beta particle. The beta particle is captured within a housing of the cobalt  60  and the photons of gamma radiation provide for the sterilization radiation process. In general, cartons  36  are brought into the irradiation plant where the cobalt  60  is transported in shielded flasks. Following transfer from the flasks to the irradiation plant, doubly encapsulated cobalt  60  in stainless steel tubes are incorporated into a three-dimensional array which form the energy source for processing carton  36  as depicted in FIG. 5 where the directional arrows  44  show impingement of the gamma radiation in a three-dimensional array direction concept. Cartons  36  are generally passed through the irradiation plant on conveyor systems either using roller beds or suspended carrier systems where the gamma radiation dose absorbed by the chemical composition within the closed cartons  36  is directly proportional to the activity level of the source and the duration of exposure.  
         [0024]    Gamma radiation is generally used for sterilization of chemical compositions in that the gamma radiation has a high penetration capability. This high penetration capability enables relatively dense products or compositions to be processed easily. Dosages are generally defined in Grays with one Gray representing the absorption of one Joule of energy per kilogram of material. Sterilizing doses generally are in the 25-35 kilogray range and as the products undergo the irradiation process, obviously the face of carton  36  facing the source of radiation will receive a higher dosage than the side away from the source.  
         [0025]    To insure appropriate dose levels between 20-40 kilograys, carton  36  is measured with dosimeters which measure the amount of irradiation impinging on the closed carton  36 . In this manner, the contents of container  20  is assured of appropriate irradiation levels being applied thereto.  
         [0026]    The closed cartons  36  are then prepared for shipping as provide in block  44  of FIG. 1 and are transported for operational use downstream.  
         [0027]    In this manner, when received at the operational site, closed cartons  36  may be then opened and third sealing layer  38  contained therein may be removed on the loading dock prior to entry into a clean room. The chemical containers  20  are maintained within third sealing layer  38  in a closed manner until removed and then brought to a clean room type operating site with the opened container  36  being left on the loading dock.  
         [0028]    Once transported into the clean room or other operational site, third sealing layer  38  may be removed and the chemical containers  20  forming second layer sealed container enclosures  32  may be placed on a shelf for future use. It must be remembered that at this point, there is both a first layer  24  and a second sealing layer  30  encompassing chemical container  20 . When placing the second layer sealed container enclosures  32  on the shelves for use in the clean rooms, generally sterilized gloves are used however, these in themselves as well as the atmosphere of clean rooms have various particulates such as microbes or bacteria which dictate a shelf life for chemical containers  20  if only a single first layer  24  were formed around the chemical containers  20 . However, with the first and second layers  24  and  30 , the now somewhat less than sterilized second layer sealed container enclosure  32  may be kept on the shelf for an indefinite period of time prior to use of the contents of chemical container  20 .  
         [0029]    Once the contents of chemical container  20  are to be used, second sealing layer  30  may be stripped from second layer sealed container enclosure  32  leaving first layer  24  surrounding and encasing chemical container  20  in a sterilized manner. Use then can be made of the contents of chemical containers  20  with the assurance that such has been maintained in a sterilized state.  
         [0030]    Thus, there has been shown a method of sterilization for chemical compositions in general and in particular isopropyl alcohol compositions where the chemical composition to be sterilized is provided prior to block  10 . In overall concept the chemical composition is secondarily tested for its appropriate concentration in block  16  with an additional test for particulate or microscopic material being made in block  14 . A container  20  is then charged with the chemical composition as provided in block  18  and container  20  is encased within first sealing layer  24  forming a single layer sealed container enclosure  26  as provided in block  22 .  
         [0031]    After the first sealing layer  24  is applied, the single layer sealed container enclosure  26  is then encased within second sealing layer  30  forming a second layer sealed container enclosure  32  as provided in flow block  28 . The encasement is provided for hermetically sealing initially the chemical container  20  with the first layer  24  and then the single layer sealed enclosure  26  with the second sealing layer  30  as shown in FIGS. 2 and 3.  
         [0032]    The second layer sealed container enclosure  32  is then inserted into an open carton member  36  which is lined with a third sealing layer  38  as shown in flow block  34  and depicted in FIG. 4. The carton member is then closed as depicted in FIG. 5 and irradiated at a predetermined radiation level for some predetermined time interval for sterilizing the chemical composition contained within container  20 .  
         [0033]    Although this invention has been described in connection with specific forms and embodiments thereof, it will be appreciated that various modifications other than those discussed above may be resorted to without departing from the spirit or scope of the invention. For example, equivalent elements may be substituted for those specifically shown and described, certain features may be used independently of other features, and in certain cases, particular locations of elements may be reversed or interposed, all without departing from the spirit or scope of the invention as defined in the appended claims.