Advance preparation of some patch test series should be avoided

摘要

For practical reasons, dermatology departments may prepare patch test allergens diluted in petrolatum hours or days in advance. Commercial allergens are commonly laid out in aluminium Finn (Epitest Ltd, Oy, Finland) or plastic IQ (Chemo-technique Diagnostics, Vellinge, Sweden) chambers (the latter have their own covers). Usually, allergens are kept refrigerated until the time of application. Allergens in aqueous or acetone solutions dropped onto filter paper are added at the last minute; otherwise evaporation of the liquid solvent might cause the concentration of the allergen to increase.