Ethylene Oxide and Ethylene Chlorohydrin Analysis in Medical Devices and Related Products Using GC-FID Head Space Sampling: Methodology and Significance

Because medical device manufacturing is fundamentally human-centred, the quality, sterility and biocompatibility of the materials produced make manufacturing processes even more precise and specialized. Materials produced through special processes are prepared for market sale. Following the necessary maintenance, cleaning and disinfection procedures, sterilization is performed as the final step. The most suitable sterilization method is selected according to the material's characteristics. Once the material is free of all microorganisms, it is packaged appropriately and made ready for use. Generally, three different sterilization methods are encountered. • Steam or dry heat sterilization, • Gamma sterilization, • Ethylene oxide sterilization Each of these three methods has advantages and disadvantages relative to the others. In this article, we will discuss ethylene oxide sterilization and the ethylene oxide and ethylene chlorohydrin residue analyses that are important following the sterilization process. Ethylene oxide is a colorless, slightly odorous gas that is slightly heavier than air, flammable and explosive, and toxic. Ethylene oxide was discovered in 1859 and initially used for fumigation purposes. It began to be used for sterilization during World War II. In modern medical manufacturing, sterilization using ethylene oxide is one of the most preferred sterilization methods. It is compatible with many medical materials and is the preferred method, especially for heat- and moisture-sensitive plastic materials.

The exposure times of products to ethylene oxide gas can vary. The sterilizer capacity used during this time, the purity of the ethylene oxide, and the raw material and structure of the sterilized product are effective factors.

During the exposure period, stable temperature and humidity values in the chamber are required to be monitored. Excessive fluctuations will cause problems during device validation. After exposure, the rinsing process is carried out and ethylene oxide is removed. Ethylene chlorohydrin is an irritant to body surfaces, showing acute toxicity and a flammable liquid that can be rapidly absorbed through the skin in toxic amounts. It appears as a byproduct during ethylene oxide sterilization. Using the ISO 10993-7 method, residual ethylene oxide present in medical devices and related products that have been exposed during or after sterilization for a specified period is determined. During this determination, the entire sample or an amount representing the sample is extracted with water for a specified time (the extraction process is generally 24 hours. However, this period may vary depending on the intended use). The ethylene oxide residue in the extract is determined using a gas chromatography device. Sample extraction of the extract is performed using headspace. The sample equilibrated in the headspace with vapor is introduced into the column in gaseous form, and the amount of residual ethylene oxide in the sample is determined using the gas chromatography device.SaniterThe conditions for removing ethylene oxide after the exposure process are important for the limit values mentioned in ISO 10993-7 and specified in the table below. Therefore, ethylene oxide and ethylene chlorohydrin analyses must be performed on the final sample that will reach the consumer after the production stage and controls must be carried out.

Summary of acceptable limits for EO and ECH (limits for each device)

  Büşra Gökdemir Chemistry Department Head