Variation in allergen content over time of acrylates/methacrylates in patch test preparations

P>Background Acrylates/methacrylates are volatile substances. There might be a gradual decrease in acrylate/methacrylate allergen content over time in patch test preparations but this has not yet been documented. Objectives To determine the allergen content of acrylates/methacrylates in patch test preparations over time under different storage conditions. Methods Five acrylate/methacrylate allergens [2-hydroxyethyl methacrylate (2-HEMA), methyl methacrylate (MMA), ethylene glycol dimethacrylate (EGDMA), triethylene glycol diacrylate (TREGDA) and 2-hydroxypropyl acrylate (2-HPA)] in syringes and IQ (TM) chambers (Chemotechnique Diagnostics, Vellinge, Sweden) were analysed using gel permeation chromatography and high-performance liquid chromatography to measure the allergen content over time in samples stored in the freezer, refrigerator and under room temperature. Results The concentration of allergens in syringes decreased with time. Those stored at room temperature had the fastest rate of decrease, followed by those in the refrigerator and freezer. In most cases, in syringes or IQ (TM) chambers under all storage conditions, the MMA decreased most rapidly, followed by 2-HPA, 2-HEMA, EGDMA and TREGDA. The allergens in the IQ (TM) chambers rapidly disappeared, with almost all samples reaching nondetectable levels by day 8. MMA was the first to reach a nondetectable level - at day 2. Conclusions Acrylate/methacrylate allergens are lost rapidly from IQ (TM) chambers especially if stored at room temperature. Allergens in syringes remain above 80% of their initial concentrations for longer periods compared with IQ (TM) chambers. In syringes and IQ (TM) chambers there is a slower rate of decrease in concentration when the storage temperature is lower. Allergens should be stored refrigerated, replaced regularly, and freshly applied on to test patches on the day of use.