Ethylene oxide monitoring

Only the first of these characteristics (use of spores of B. subtilis var niger ATCC 9372 or NCTC 1(X)73) is without some form of coniplicalion with regard to ethylene oxide monitors. 

General recommendations for instmmentation include monitoring gas concentration, temperature, time, and the moisture content of the chamber. Hospital sterilizers are not usually equipped with instmmentation providing direct display of gas concentration and moisture content. These rely instead on a specific sequence of steps performed automatically and the recording of pressure which when 100% ethylene oxide is used is a perfect measure for the concentration of this gas. 

Figure 13.22 shows the resolution of the surfactants Tween 80 and SPAN. The high resolution obtained will even allow the individual unreacted ethylene oxide oligomers to be monitored. Figure 13.23 details the resolution of many species in both new and aged cooking oil. Perhaps the most unique high resolution low molecular weight SEC separation we have been able to obtain is shown in Fig. 13.24. Using 1,2,4-trichlorobenzene as the mobile phase at 145°C with a six column 500-A set in series, we were able to resolve Cg, C, Cy, Cg, C9, Cio, and so on hydrocarbons, a separation by size of only a methylene group. Individual ethylene groups were at least partially resolved out to Cjg. This type of separation should be ideal for complex wax analysis.

Treatment of quinoline with ethylene oxide gave oxazolo[3,2-u]quinoline 597 whereas 2-methylquinoline did not react with ethylene oxide (79JOC285). The oxazolidine 597 is labile as monitored by H NMR spectroscopy its colorless solution in CDCI3 became dark red within several hours (Scheme 100). 

So long as a compound has a fairly intense absorption which is unlikely to overlap with those of other substances with which it is likely to be mixed, then it is possible to monitor that substance on a continuous basis with a dedicated infrared detector. Gases such as carbon dioxide, nitrogen oxides, ethylene oxide and ammonia can now be measured and regulated using these devices. 

The operation of an ethylene oxide sterilizer should be monitored and controlled automatically. A typical operating cycle for pure ethylene oxide gas is given in Fig. 20.7, and general eonditions are summarized in section 10. 

In the case of ethylene oxide sterilization, rather more detail is included on the information expected in an MAA description of the sterilizer and associated facilities, the gas concentration used, bioburden monitoring and limits prior to exposure to gas, gas exposure time, temperature and humidity prior to exposure and during the exposure cycle, and the conditions under which ethylene oxide desorption is undertaken. 

Collins M, Barker NJ. 1983. Direct monitoring of ambient air for ethylene oxide and ethylene dibromide. Am Lab 15 72, 74-76, 78-81. 

Preston RJ Cytogenetic effects of ethylene oxide, with an emphasis on population monitoring. Crit Rev Toxicol 29(3) 263-282, 1999... 

The simulated test atmosphere with high levels of contaminant (2 to 5ppm) were analyzed by both the in-line GC (in the primary dilution module) and by direct injection of air taken from the sampling port (in the secondary dilution module). The purpose of the latter was to establish the reliability of the in-line GC. The in-line monitor was particularly important in test atmosphere with low contaminant concentration because in this case, direct injection of the air is not feasible. Table I compares the results obtained by the in-line GC and direct air injection for ethylene oxide and acetone. 

Lawrence, R.M., Sweetman, G.M.A., Tavares, R. Farmer, P.B. (1996) Synthesis and characterization of peptide adducts for use in monitoring human exposure to acrylonitrile and ethylene oxide. Teratog. Carcinog. Mu tag.. 16, 139-148... 

In addition, the testing laboratory for both nutrients and unintentional contaminants, including carcinogens, may perform periodic analysis of the basal diet. The results of such analysis should be retained and included in the final report on each chemical. When the test chemical is administered in water or food, stability tests are essential. Properly conducted stability and homogeneity tests, prior to the chronic study, should be used to establish the frequency of diet preparation and monitoring required. When diets are sterilized, the effects of such procedures on the test chemical and dietary constituents should be known. Appropriate adjustments to nutrient levels should be performed. The effect of chemical sterilants, (e.g., ethylene oxide) on the bioassay should be ascertained. 

The methods of preparation of glassware are indicated in Chapter 8, and if sterilisation is monitored as described the glassware should not be a source of contamination. Likewise plasticware is obtained from the manufacturer in a sterile condition. Usually sterilisation of plastic is achieved using ethylene oxide or irradiation procedures and vessels are supplied wrapped in cellophane. 

Production of all these products is exactly the same as that for nonylphenol ethoxylates. The alcohol feedstock is dehydrated at around 130°C under vacuum, the relevant amount of catalyst, (NaOH or KOH) added, the reactor padded with nitrogen and ethylene oxide added, the feed rate being controlled by monitoring the reaction conditions. 

The most reliable method of detecting a runaway is online analysis of a product formed in the runaway reaction. For example, CO2 can be monitored in the offgas during the runaway-sensitive synthesis of ethylene oxide. If its concentration increases above a specified limit, the reactor must be shut down, purged with nitrogen, and for a certain period cooled to a lower temperature before operation is recommenced. 

Process Conditions for Ethylene Oxide. Exposure to ethylene oxide lasted 4, 6.5, and 15 hr. To keep the relative humidity at the necessary percent (1, 2, 3), water vapor was added to the chamber of the VDF. Exposure of the books to ethylene oxide occurred at either room temperature or at an elevated temperature. When the maximum temperature in the chamber in the latter case was set for approximately 40 °C, it took about 60 min to get to 33 °C and 3 hr to reach the maxium value. The temperature changes of the gas throughout the chamber after closing the chamber door were determined by placing a series of thermocouples both inside and outside of the books at different positions on the cart. A maximum difference of 11 °C was recorded upon entry of the gas into the chamber between a pair of these thermocouples positioned on the bottom shelf. The difference was reduced to 1°C after 8 min of exposure. Temperatures at the various positions were monitored throughout the entire experiment. 

Pinto, T.J.A. Saito, T. lossif, M. Ethylene oxide sterilization III—influence of carrier nature in a biological monitor performance. PDA J. Pharm. Sci. Technol. 1994, 48 (3),... 

Ethylene oxide alkylates nucleophilic groups in biological macromolecules. Hemoglobin adducts have been used to monitor tissue doses of ethylene oxide (7). 

If contact with the liquid or its solutions occurs, affected areas should be flushed thoroughly with water for at least 15 min. The areas should be observed for burns or resulting irritation. In case of inhalation of ethylene oxide, the victim should be moved to fresh air, an airway should be established, and respiration should be maintained as necessary. The victim should be monitored for irritation, bronchitis, and pneumonitis. If excessive exposure occurs, hospitalization and monitoring for delayed pulmonary edema is recommended. 

After treatment, the gases are evacuated either directly to the outside atmosphere or through a special exhaust system. Filtered, sterile air is then admitted either for a repeat of the vacuum/air cycle or for air purging until the chamber is opened. In this way, safe removal of the ethylene oxide is achieved, reducing the toxic hazard to the operator. Sterilized articles are removed directly from the chamber and arranged for desorption. The operation of an ethylene oxide sterilizer should be monitored and controlled automatically. A typical... 

Fourier-transform infrared spectroscopy (FTIR) and pH measurements are the techniques most often adapted for in-line IPC. pH measurements are used for reactions that are run in water or have an aqueous component, e.g., an aqueous extraction. FTIR is especially good for monitoring continuous reactions [12] and reactions that would be dramatically changed by exposure to the atmosphere and temperature of the laboratory. Suitable reactions include low-temperature reactions, reactions run under pressure, reactions with gaseous or toxic materials (e.g., ethylene oxide), and reactions run under inert atmosphere. Further advantages of in-line assays are that no samples need to be prepared, and assay results can be generated within minutes. 

Much work has been reported on studying the structure of thermoset resins via SAXS, especially focussing on interpenetrating network polymers (IPNs), thermoset nanocomposites, rubber-modified thermosets and thermoset-thermoplastic blends. Most recently Guo et al, (2003) have examined the use of SAXS to monitor the nanostructure and crystalline phase structure of epoxy-poly(ethylene-ethylene oxide) thermoset-thermoplastic blends. This work proposes novel controlled crystallization due to nanoscale confinements. 

Real-time monitoring of fusion and fission has been reported for polymer vesicles generated from an amphiphilic multiarm copolymer with a hyperbranched poly(3-ethyl-3-oxetanemethanol) core and many oligo(ethylene oxide) arms (HBPO-star-PEO) [152,153], Sonication could partly break the hydrogen bonds and give rise to molecular packing defects on the membrane, which triggers the membrane fusion. 

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