Patent Application
20240033389
The present invention relates to the detection vapor peracetic acid (PAA) and hydrogen peroxide. It finds particular application in the sensing of vapor peracetic acid and hydrogen peroxide concentrations.
Advanced medical instruments formed of rubber and plastic components with adhesives are delicate and often unsuited to the high temperatures and pressures associated with a conventional steam autoclave. Steam autoclaves often operate under pressure cycling programs to increase the rate of steam penetration into the medical devices or associated packages of medical devices undergoing sterilization. Steam sterilization using gravity, high pressure, or pre-vacuum, creates an environment where rapid changes in temperature or pressure can take place. Complex instruments which are often formed and assembled with very precise dimensions, close assembly tolerances, and sensitive optical components, such as endoscopes, may be destroyed or have their useful lives severely curtailed by harsh sterilization methods employing high temperatures and high or low pressures.
Endoscopes can present certain problems in that such devices typically have numerous exterior crevices and interior lumens which can harbor microbes. Microbes can be found on surfaces in such crevices and interior lumens as well as on exterior surfaces of the endoscope. Other medical or dental instruments which comprise lumens, crevices, and the like can also provide challenges for decontaminating various internal and external surfaces that can harbor microbes.
Decontamination systems and methods that utilize peracetic acid and/or hydrogen peroxide chemistry are known. For example, PCT Patent Application No. PCT/US17/59670 and U.S. Patent Application 2016/0346416 both of which are incorporated by reference in their entirety, disclose decontamination or sterilization systems that utilize peracetic acid and/or hydrogen peroxide.
While current systems set cycle parameters to avoid oversaturation of the vapor, the saturation of the process has not typically been monitored or controlled.
There is a need for a system and method for detecting the presence and concentration of peracetic acid vapor and hydrogen peroxide vapor, preferably during a sterilization or decontamination cycle, in order to verify the presence and/or efficacy of the cycle.
In one aspect, the present invention is directed to a peracetic acid vapor and hydrogen peroxide vapor detection system. The system includes (a) a source of peracetic acid vapor, hydrogen peroxide vapor, water vapor and acetic acid vapor, (b) a light source which is configured to supply light with at least a component in the mid-infrared range, and (c) a detector which is configured to individually detect mid-infrared range light in (i) a first mid-infrared spectrum absorbed by the peracetic acid vapor and not absorbed by the hydrogen peroxide vapor, the acetic acid vapor or the water vapor, and (ii) a second mid-infrared spectrum absorbed by the peracetic acid vapor and the hydrogen peroxide vapor.
In another aspect, the present invention is directed to a peracetic acid and hydrogen peroxide treatment system. The system includes (a) a treatment chamber, (b) a vaporizer configured for generating a mixture of peracetic acid vapor, hydrogen peroxide vapor, water vapor and acetic acid vapor and supplying the vapor mixture to the treatment chamber, (c) a light source which is configured to supply light to the treatment chamber with at least a component in the mid-infrared range, (d) a detector which individually detects mid-infrared range light in a first spectrum absorbed by peracetic acid vapor and not any of the hydrogen peroxide vapor, water vapor and acetic acid vapor, and a second spectrum absorbed by the peracetic acid vapor and the hydrogen peroxide vapor, and (e) a processor configured to determine the concentration of the peracetic acid vapor in the treatment chamber.
In another aspect, the present invention is directed to a disinfection or sterilization system. The system includes (a) a treatment chamber, (b) a vaporizer configured to vaporize an aqueous solution comprising peracetic acid, hydrogen peroxide, acetic acid and water to form a mixture of peracetic acid vapor, a hydrogen peroxide vapor, an acetic acid vapor and a water vapor and for supplying the mixture of vapors to the treatment chamber, (c) a light source which is configured to project a beam of light in a mid-infrared range through the mixture of vapors, (d) a mid-infrared light detector which is configured to detect a first spectrum absorbed by the peracetic acid vapor and not any of the hydrogen peroxide vapor, the acetic acid vapor and the water vapor, and a second spectrum absorbed by the peracetic acid vapor and the hydrogen peroxide vapor, (e) a first processor which is configured to convert the detected first and second spectrum light into one of (i) absorbance values indicative of mid infrared light absorbed by the peracetic acid and hydrogen peroxide vapors and (ii) transmittance values indicative of mid-infrared light transmitted through the peracetic acid and hydrogen peroxide vapors, and (f) a second processor which is configured to convert the determined absorbance or transmittance values into a concentration of the peracetic acid vapor and a concentration of the hydrogen peroxide vapor.
In another aspect, the present invention is directed to a method for detecting the presence of peracetic acid and hydrogen peroxide in a vapor mixture. The method includes the steps of a) providing a vaporized mixture comprising peracetic acid, hydrogen peroxide, acetic acid, and water into a chamber, b) projecting light in a mid-infrared range through a portion of the vaporized mixture that has passed through at least a portion of the chamber, (c) detecting mid-infrared light in a first spectrum absorbed by the peracetic acid vapor and not any of the hydrogen peroxide vapor, the acetic acid vapor and the water vapor, and a second narrow spectrum absorbed by a peracetic acid vapor and hydrogen peroxide vapor, and (d) detecting mid-infrared light in a second spectrum absorbed by the peracetic acid vapor and the hydrogen peroxide vapor.
In another aspect, the present invention is directed to a method for detecting the presence of peracetic acid and hydrogen peroxide in a vapor mixture. The method includes the steps of (a) providing a vaporized mixture comprising peracetic acid, hydrogen peroxide, acetic acid, and water into a chamber, (b) projecting light in a mid-infrared range through a portion of the vapor mixture that has passed through a portion of the chamber, (c) detecting mid-infrared light in a first spectrum absorbed by the peracetic acid vapor and not any of the hydrogen peroxide vapor, the acetic acid vapor and the water vapor, and a second narrow spectrum absorbed by a peracetic acid vapor and hydrogen peroxide vapor, (d) projecting light in a near-infrared range through the monitored region of the chamber, and (e) detecting near-infrared light in a spectrum absorbed by the peracetic acid vapor, the hydrogen peroxide vapor and the acetic acid vapor.
While multiple embodiments are disclosed, still other embodiments of the present invention will become apparent to those skilled in the art from the following detailed description, which shows and describes illustrative embodiments of the invention. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not restrictive. All references cited in the instant specification are incorporated by reference for all purposes. Moreover, as the patent and non-patent literature relating to the subject matter disclosed and/or claimed herein is substantial, many relevant references are available to a skilled artisan that will provide further instruction with respect to such subject matter.
The invention may take form in various components and arrangements of components, and in various steps and arrangements of steps. The drawings are only for purposes of illustrating preferred embodiments and are not be construed as limiting the invention.
Devices, such as medical devices, can be decontaminated or sterilized at relatively low temperatures using vaporized mixture of peracetic acid, hydrogen peroxide, acetic acid and water. In such systems, the chemistry may be provided as a vapor into a decontamination chamber containing the device to be decontaminated. The surfaces of the device will be decontaminated when contacted with the chemistry. Lumen devices may be particularly challenging to decontaminate as there must be flow of the decontaminating substance through the lumen. The instant disclosure describes a system for detecting the presence and/or concentration of peracetic acid vapor, hydrogen peroxide vapor and optionally, acetic acid vapor during the decontamination or sterilization process. A method of using is also described.
The vapor detection systems and methods of the present invention can be used alone or in combination with sterilization or decontamination systems, such as those disclosed in PCT Patent Application No. PCT/US17/59670 and U.S. Patent Application 2016/0346416 both of which are incorporated by reference in their entirety.
The present invention is directed to a system and method which includes detecting the absorbance of the vapor mixture (peracetic acid vapor, hydrogen peroxide vapor, acetic acid vapor and water vapor), for example, by passing the mixture through a gas cell, in the mid-infrared (MIR) range (which is defined as 4000 cm−1 to 400 cm−1), and also optionally in the near infrared (NIR) range (700 nm to 2500 nm). The system or method, or various components of the system or method, can be located or carried out inside of a decontamination or sterilization chamber, or outside of the chamber.
In one embodiment, the system is a detection system. In another embodiment, the system is a treatment system. The treatment system can be disinfection or sterilization and can be used for medical devices, such as endoscopes.
An exemplary mid-infrared spectrum of the peracetic acid/hydrogen peroxide/acetic acid/water system is shown in
It is believed that the absorbance of the peracetic acid band which shows a set of peaks between 1200 cm−1 and 1140 cm−1 in
As shown in
As shown in
The PAA absorbance is also present as a triplet of peaks between 3270 cm−1 and 3330 cm−1 (not shown). In this region, the absorbance is also only due to peracetic acid, as the other components do not absorb in this band.
Likewise, there is another triplet of peaks due to peracetic acid in the MIR region from 1200 cm−1 to 1280 cm−1 as shown in
In these bands, the absorbance can be correlated to the concentration, because the vapor absorbance of infrared light obeys Beer's law. The concentration of peracetic acid can thus be shown to be linear and quantitative, for example, as shown in
As shown in
Additionally, the detection of infrared light in the MIR region between 1220 cm−1 to about 1260 cm−1 yields absorbance data for hydrogen peroxide and peracetic acid. By using chemometrics (since the concentration and the absorbance per mole of the peracetic acid is known) to subtract the contribution of peracetic acid to this region, the vapor phase concentration of hydrogen peroxide is calculated.
The detection of infrared light in the MIR region between 1140 cm−1 to about 1200 cm−1 yields absorbance data for acetic acid.
Thus, using the MIR data, and calculation known to those of skill in the art, the vapor phase concentration of peracetic acid, hydrogen peroxide and acetic acid in the 4-component system can be obtained.
The absorbances due to hydrogen peroxide can be less able to be resolved in the MIR, since the overlap with the peracetic acid peak in the region from 1200 cm−1 to 1260 cm−1 lowers the resolution that is possible with conventional spectroscopic techniques.
In one embodiment, in order to improve the resolution of the hydrogen peroxide and the acetic acid, the NIR spectrum of the system is used. The NIR spectrum of the system is shown in
As can be seen in
Thus, using MIR, and optionally NIR data, and some calculation, the vapor phase concentration of peracetic acid, hydrogen peroxide and acetic acid, and peracetic acid in this 4-component system can be individually determined.
The present invention is directed to a peroxy vapor (peroxyacetic acid) and hydrogen peroxide vapor detection system and methods. The system may include (a) a source of peracetic acid vapor, hydrogen peroxide vapor, water vapor and acetic acid vapor, (b) a light source which is configured to supply light with at least a component in the mid-infrared range, and (c) a detector which is configured to individually detect mid-infrared range light in (i) a first mid-infrared spectrum absorbed by the peracetic acid vapor and not absorbed by the hydrogen peroxide vapor, the acetic acid vapor or the water vapor, and (ii) a second mid-infrared spectrum absorbed by the peracetic acid vapor and the hydrogen peroxide vapor.
In one embodiment, a decontamination or sterilization fluid, such as Rapicide PA Sterilant, provided by Medivators (Minneapolis, MN) is utilized. The fluid contains peracetic acid, hydrogen peroxide, acetic acid and water. The fluid may be in liquid form or in vapor form. In an embodiment where the fluid is in liquid form, the liquid is vaporized prior to introduction into the system or method.
The system and method also include a light source which is configured to supply light with at least a component in the mid-infrared range. The light source can be located in the chamber or outside of the chamber. The light source is configured to supply light to the vapor mixture. In one embodiment, the light is in a first mid-infrared spectrum absorbed by the peracetic acid vapor and not absorbed by the hydrogen peroxide vapor, the acetic acid vapor or the water vapor, for example, from about 920 cm−1 to about 970 −1, from about 830 cm−1 to about 880 cm−1, or from about 1220 cm−1 to about 1260 cm−1. In another embodiment, the light is in a second mid-infrared spectrum absorbed by the peracetic acid vapor and the hydrogen peroxide vapor, such as from about 1220 cm−1 to about 1260 cm−1. In another embodiment, the light is in a third mid-infrared spectrum absorbed by the acetic acid vapor, for example, from about 1140 cm−1 to about 1200 cm−1. In another embodiment, the light is in the near infrared spectrum. The light in the near infrared spectrum can be absorbed by the peracetic acid vapor, the hydrogen peroxide vapor and the acetic acid vapor, for example, from about 1390 nm to about 1430 nm.
In one embodiment, the light source is a single light source that supplies the light in the mid-infrared spectrum. In another embodiment, the system or method utilizes multiple light sources to supply light in narrow ranges in the mid infrared spectrum. In another embodiment, a separate light source supplies light in the near infrared spectrum.
In one embodiment, the light source supplies light to the vapor mixture prior to a disinfection or sterilization step. In another embodiment, the light source supplies light to the vapor mixture during a disinfection or sterilization step. In another embodiment, the light source supplies light to the vapor mixture after a disinfection or sterilization step. In another embodiment, the light source supplies light at various times during the process.
In one embodiment, the light is supplied into the chamber. In another embodiment, the vapor mixture is sampled and placed into a gas cell, where the light is supplied.
The system and method of the present invention also include a detector which is configured to individually detect mid-infrared range light. In one embodiment, the detector detects light in a first mid-infrared spectrum absorbed by the peracetic acid vapor and not absorbed by the hydrogen peroxide vapor, the acetic acid vapor or the water vapor, for example, from about 920 cm−1 to about 970 cm−1, from about 830 cm−1 to about 880 cm−1, or from about 1220 cm−1 to about 1260 cm−1. In another embodiment, the detector detects light in a second mid-infrared spectrum absorbed by the peracetic acid vapor and the hydrogen peroxide vapor, such as from about 1220 cm−1 to about 1260 cm−1. In another embodiment, the detector detects light in a third mid-infrared spectrum absorbed by the acetic acid vapor, for example, from about 1140 cm−1 to about 1200 cm−1. In another embodiment, the detector detects light in the near infrared spectrum. The light in the near infrared spectrum can be absorbed by the peracetic acid vapor, the hydrogen peroxide vapor and the acetic acid vapor, for example, from about 1390 nm to about 1430 nm.
In one embodiment, the detector which detects mid-infrared light and the detector which detects near-infrared light are a single detector. In another embodiment, the detector which detects mid-infrared light and the detector which detects near-infrared light are separate detectors.
The detector can be located in the chamber or outside of the chamber. In one embodiment, the vapor mixture can be pulled or sampled from the chamber and analyzed. In another embodiment, the detector can be placed in-line on a scope flow channel to analyze gas coming through the scope from inside the chamber.
In one embodiment, the systems and methods of the present invention may also include a processor. The processor is configured to determine at least a concentration of the peracetic acid vapor from the detected light in the first mid-infrared spectrum. In another embodiment the processor can also determine a concentration of the hydrogen peroxide, and/or acetic acid vapor. The processor can be configured to calculate the concentrations from the detected light in the MIR range as well as the NIR range.
In one embodiment, the processor is configured to determine at least one of (a) an absorbance of light in the first mid-infrared spectrum and (b) a transmittance of light in the first mid-infrared spectrum, and is further configured to convert the determined absorbance or transmittance into the concentration of the peracetic acid vapor.
In another embodiment the processor is configured to determine at least one of (a) an absorbance of light in the second mid-infrared spectrum and (b) a transmittance of light in the second mid-infrared spectrum, and to convert the determined absorbance or transmittance into a concentration of the hydrogen peroxide vapor.
In another embodiment, the processor is configured to determine at least one of (a) an absorbance of light in the third mid-infrared spectrum and (b) a transmittance of light in the third mid-infrared spectrum, and to convert the determined absorbance or transmittance into a concentration of the acetic acid vapor
In another embodiment, the processor is configured to determine at least one of (a) an absorbance of light in the near-infrared spectrum and (b) a transmittance of light in the near-infrared spectrum, and to convert the determined absorbance or transmittance into a concentration of the hydrogen peroxide vapor.
In one embodiment, the IR absorbance of PAA is calculated as follows:
In one embodiment, the IR absorbance of H2O2 is calculated as follows:
The cycle of
In some embodiments, the vacuum preconditioning step 610 may be followed by the first decontamination or sterilization step 620. During the first decontamination or sterilization step 620, the vapor mixture is injected into the chamber in a first injection step 650. During the first injection step 650 the pressure within the chamber increases. In an example embodiment, the vapor mixture is injected into the decontamination chamber during the first injection step 650. The vapor mixture may be injected into the chamber at a single injection at a constant rate as shown in the first injection step 650 or it may be injected in a plurality of stepwise injections.
The first injection step 650 may be optionally followed by a pressure increase step 651. During the pressure increase step 651, the pressure inside the chamber is increased to a suitable pressure determined to increase the effectiveness of a decontamination or sterilization process. After the vapor mixture is injected, it may be optionally allowed to diffuse throughout the chamber in a diffusion period 652 while the pressure is held steady. In some embodiments, the optional diffusion period 652 is not used.
In some embodiments, after the diffusion period 652, a second pump down 654 may be carried out. During the second pump down 654, the pressure within the chamber decreases. The second decontamination or sterilization step 630 is carried out after the second pump down 654. During the second decontamination or sterilization step 630, a second injection step 660 may be used to add the vapor mixture to the decontamination chamber while the pressure within the chamber increases. The second injection step 660 may include adding the vapor mixture into the decontamination chamber in a single injection step or in a plurality of stepwise injection steps that may be used to gradually add the vapor mixture to the chamber.
In some embodiments, a pump may be used to direct air within the chamber through the lumen or lumens of the device in coordination with the cycle. For example, during the first injection step 650, the second injection step 660 or both injection steps, a pump may be used to direct air within the chamber towards and/or through the lumens of the device. In some embodiments, the pump may be turned on before or during either the first or second injection step 650, 660. For example, the pump may be turned on with or substantially with the first and/or second injection steps 650, 660. In some embodiments, the pump may turn on before or during the first injection step 650 and may turn off at the end of or after the first injection step 650. Additionally or alternatively, the pump may turn on before or during the second injection step 660 and may turn off after or at the end of the second injection step 660. In some embodiments, the pump may turn on before or during both the first and second injection steps 650, 660, or the pump may be turned on before or at the beginning of the first injection step 650 and may be turned off during or after the end of the second injection step 660.
After the second injection step 660, a plurality of air washes 662 may be carried out. As shown in
Illumination and detection of the vapor mixture can occur at any point in the process. In one embodiment, the vapor mixture is analyzed throughout the process.
The following paragraphs provide for various aspects of the present invention.
In one embodiment, in a first paragraph (1), the present invention provides a peracetic acid vapor and hydrogen peroxide vapor detection system, the system comprising a source of peracetic acid vapor, hydrogen peroxide vapor, water vapor and acetic acid vapor: a light source configured to supply light with at least a component in the mid-infrared range; and a detector configured to individually detect mid-infrared range light in (a) a first mid-infrared spectrum absorbed by the peracetic acid vapor and not absorbed by the hydrogen peroxide vapor, the acetic acid vapor or the water vapor, and (b) a second mid-infrared spectrum absorbed by the peracetic acid vapor and the hydrogen peroxide vapor.
The invention has been described with reference to the preferred embodiments. Obviously, modifications and alterations will occur to others upon reading and understanding the preceding detailed description. It is intended that the invention be construed as including all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.
The following examples illustrate the principles and advantages of the invention.
Low temperature sterilization system (LTSS) with IR sampler
A Revox low temperature sterilization system (LTSS) model number 5434 (Serial number RVXM5434) was configured with an experimental infrared vapor detector (EVD) inline to a selected scope flow channel. The EVD was programed to capture a 6-scan-averaged infrared spectrum from 1300 to 800 cm−1 every ten seconds using a resolution of 4 cm−1. Infrared data collection was set to begin the moment the LTSS cycle was started.
The LTSS was configured to deliver 5.0 mL of vaporized Revox PA sterilant (peracetic acid, hydrogen peroxide, acetic acid and water from Medivators) into a 417-liter vacuum chamber after the vacuum pressure had reached 10 torr. Sterilant injection resulted in a final system pressure of 150 torr at which point the system's scope flow channels were turned on to allow chamber gasses to pass through the EVD. Scope flow was allowed to continue for 900 seconds and the system was then ventilated using a 4 cycle ventilation process. Infrared data collection was set to stop once the ventilation cycles were completed.
Spectra signals were monitored in time and are shown in
The experimental setup included three key components, 1) the Thermo Nicolet 380 FTIR system running the Thermo Omnic Software, 2) the Nicolet 2 meter gas accessory, and 3) a Thermo MCTA liquid nitrogen detector. Gas analysis was performed by connecting the main large sterilization chamber to the 2 m gas cell so that all gas species could be detected/monitored in real time during the entire sterilization cycle. A Thermo Nicolet Avatar 380 FTIR was used in its standard configuration (with a KBR beamsplitter) and an MCTA detector. The MCTA detector is preferred since it provides 10×higher sensitivity compared with standard room temperature DTGS detector. Long path length cells (2 m and higher) intrinsically lose light due their long path length, thus making the MCTA detector a better option. During the entire cycle, data points were taken every 10 s (with averaging) to get repeatable results with high signal to noise ratios.
The Thermo Avatar 380 FTIR had a minimum resolution of 4 cm−1, utilizing a 24 bit A/D, USB 2.0, a Mid IR source, and a resolution of 4 wavenumbers and a scan speed of 6 scans per data point. all done in absorbance mode. The background was taken and stored just prior to introducing the liquids in vacuum. Automatic logging was used in Omnic to store each trace in SPA file format every 10 s. The Mid Infrared spectral range for the enitre system was 7000-650 cm−1. The 2 m gas cell had a volume of 200 mL with detection limits capable of 50-200 ppb. The smaller size of the 2 m cell is preferred over larger cells (10 m) for their low sample volumes to more accurately monitor changes in the kinetics. The Nicolet MCTA detector had the following specifications: 11700-600 cm−1, detector area: 1×1 mm{circumflex over ( )}2, D*: 4.7 e{circumflex over ( )}10 cm Hz{circumflex over ( )}1/2 W−1, response: 750 V/W, bandwidth: of 175 Hz.
The purpose of this example was to find a correlation of the FTIR absorbance of peracetic acid vapor and the concentration of peracetic acid vapor (mg/L) during the sterilization cycle by running three separate runs and generating a calibration curve. This example also shows how to find the calibration curve for peracetic acid vapor (mg/L) with peracetic acid IR absorption.
Material
Procedure:
The setup of sampling collection is shown in
Before each run, the RH and temperature sensors were placed into the chamber 702. The test cycle was started by evacuating the chamber 702 down to 10 torr. At 10 torr, the injection was started. The injection volumes tested are shown in Table 1 with the liquid flow rate and air flow rate used for the injection process.
Once the set volume of chemistry had been injected (based on the mass reading from the scale using density of 1.18 g/mL), the liquid injection was stopped and the air injection continued until the chamber attained operation pressure (100 torr for Tables 2 and 3 or 75 torr for Table 4).
Immediately after the injections, the vacuum pump 708 was turned on and FTIR chemistry sampling 704 and cold trap sampling 706 were collected for 5 min (for 0.5-3mL injection) and 3 min (for 3.5-4mL injection) after the injection process was completed. The pressure of the chamber was recorded with each sampling time (before and after the sampling process).
After the sampling process was completed, the venting process was initiated. The chamber was vented with 4 venting cycle to remove the chemistry from the chamber.
IR analysis: For all IR absorbance data, the absorbance value obtained was defined as the highest absorbance observed at 860 cm−1 during the vapor sample process compared to a baseline reading which was taken at 820 cm−1.
Cold trap sample analysis: after leaving the IR chamber 704, the gas was collected in 10 mL of water via a cold trap 706. An HPLC method for organic acids was used to analyze the total mg of vapor (H2O2, PAA, and acetic acid) in the collected sample.
A correlation curve between cold trap PAA vapor (mg/L) data with PAA-IR absorbance was then made.
Results:
The calculation of vapor concentration in mg/L, were done based on the Ideal Gas law.
Note: For the n1 and n2 calculation, the volume used was the volume of the chamber 702 which is constant at 120 L.
Table 2 shows the data for a first set of runs at 100 torr.
Table 3 shows the data for a second set of runs at 100 torr.
Table 4 shows the data for a first set of runs at 75 torr.
The purpose of this example was to calculate the PAA vapor (mg/L) concentration based on the PAA-IR calibration curve created in Example 3.
Material
Procedure
Before each run, the RH and temperature sensors were placed into the chamber. The test cycle was started by pumping the chamber down to 10 torr.
Once the chamber pressure reached 10 torr, the injection was started. The injection volumes that were tested are shown in Table 5 with the liquid flow rate and air flow rate used for the injection process.
Once the desired volume of chemistry was injected (based on the mass reading from the scale using the density of 1.18 g/mL), the liquid injection and the injection air were stopped.
Immediately after injections, the vacuum pump was turned on and FTIR chemistry sampling and cold trap sampling were collected for 5 min after the injection process was completed. The pressure of the chamber was recorded with each sampling time before and after the sampling process.
After the sampling process was completed, the venting process was begun. The chamber was vented with 4 venting cycle to remove the chemistry from the chamber.
IR analysis: For all IR absorbance data, the absorbance value obtained was defined as the highest absorbance observed at 860 cm−1 during the vapor sample process.
Cold trap sample analysis: after leaving the IR chamber, the gas was collected in 10 mL of water via a cold trap. An HPLC method for organic acids was used to calculate PAA vapor concentration.
The PAA-IR Abs. and calibration curve y=13.695x-0.0077 (from
Table 6 shows the calculation of PAA vapor with the measured PAA-IR absorption and cold trap method. The errors were less than 10% for 2.5 mL injection. The concentration of PAA vapor is about 1 mg/L.
The results above show that that it is possible to use the PAA-IR spectrum at wavelength 860 cm−1 to detect PAA vapor concentration in a sterilizer chamber.
The error of the calculation was less than 10%. To improve the standard curve, a vapor filter could be used to avoid small liquid particles getting into sample apparatus.
In light of the detailed description of the invention and the examples presented above, it can be appreciated that the several objects of the invention are achieved.
The explanations and illustrations presented herein are intended to acquaint others skilled in the art with the invention, its principles, and its practical application. Those skilled in the art may adapt and apply the invention in its numerous forms, as may be best suited to the requirements of a particular use. Accordingly, the specific embodiments of the present invention as set forth are not intended as being exhaustive or limiting of the invention.
This application is a divisional of U.S. patent application Ser. No. 16/771,265, filed Jun. 10, 2020, which is a 371 of international PCT Application with serial number PCT/US18/66851 filed Dec. 20, 2018, which claims priority to and the benefit of U.S. Provisional application with serial number 62/608,798, filed on Dec. 21, 2017, entitled SYSTEM AND METHOD FOR DETECTING PERACTIC ACID AND HYDROGEN PEROXIDE VAPOR, the contents of which are herein incorporated in their entirety for all purposes.
| Number | Date | Country | |
|---|---|---|---|
| 62608798 | Dec 2017 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 16771265 | Jun 2020 | US |
| Child | 18159796 | US |
