We have examined the influence of filter type and elution method on the levels measured for an important occupational aeroallergen, rat urine. Three filter types [glass fibre (GF/A), and two forms of polytetrafluoroethylene (PTFEG and PTFES)] and three elution methods [syringe elution ([syr]), sonication ([sonic]) and test tube ([u]) elution] were studied. There were no significant differences in the rat urinary aeroallergen (RUA) concentrations recovered from GF/A and PTFEG when eluted in syringes or by sonication (GF/A only) in 0.1 M NH4HCO3 buffer. The allergen yield from GF/A and PTFEG increased nine- and three-fold, respectively (P<0.001, P<0.05) when 0.5% v/v Tween 20 was added to the elution buffer. Up to 10% v/v Tween 20 did not alter the slope or intercept of the rat urine dilution curve. No significant difference was found in the RUA concentrations eluted from paired PTFES[xyz] and PTFEG[syr], or from paired PTFES[syr] and PTFEG[syr] We recommend that 0.5% v/v Tween 20 is added to elution buffers. PTFES[u]was found to be the simplest, most sensitive and reproducible method (40–70% variability) for aeroallergen elution.
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Gordon et al. (1992) studied this question.