Permeation of the sterilising agent in bags: a simplified routine evaluation method
Isolator sterilisation processes use peracetic acid and hydrogen peroxide (H2O2). These agents have toxic and oxidizing properties and must not therefore be present in the preparations made in the isolator. The permeability of the bags depends on the nature of the polymer but also on the sterilisation conditions   . The aim of this study is to implement a simple and transposable quantification method that can be adapted to all hospital pharmacies (PUI) making it possible to evidence and quantify the permeation of peracetic acid or H2O2.
The quantification method selected is based on the oxidation of ferrous iron into ferric iron by the H2O2 (Peroxidetect®). Quantification was performed by complexation of the ferric iron with the xylenol orange, detected by UV spectrometry UV (574 – 586 nm). The method was validated according to the recommendations of the SFSTP . The permeation of the H2O2 (Soproper®) was studied in bags in PVC (Easyflex®), in polyolefin (Macoflex®) and in a two-layer barrier bag EVA/EVOH [Ethylene Vinyl Acetate /Ethylene Vinyl Alcohol Copolymer] (Nutripoche®Barrière) sterilised with and without their outer (n = 3). The tests were performed according to 2 different sterilisation conditions:
For the JCE® isolator, analyses were performed after 1, 2 and 3 sterilisation cycles.
The method was linear from 100 to 1000 µg/l, exact (confidence interval at 95 %: 95.6 – 104.2 %) and faithful (variation coefficient for repeatability: 5.6 %).
The quantification threshold was 100 µg/l.
For all the polymers, the outer pack of the bags enabled prevention of permeability to H2O2.
The quantifiable absence of any permeation of H2O2 after 2 and 3 sterilisation cycles into the sterilised bags with an outer makes it possible to validate in our conditions their re-sterilisation if necessary.
This study made it possible to implement a simple, fast method enabling the detection of traces of the sterilising agent in different types of bag and enables the implementation of validation of routine processes upon any change in the products used.
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