In-vitro dissolution of vitreous silicate fibres according to EURIMA test guideline - results of two round robins

The EURIMA (The European Insulation Manufacturers Association) test guideline "In-vitro acellular dissolution of man-made vitreous silicate fibres" provides a state-of-the-art method for measuring in-vitro dissolution rates relevant for evaluating the bio-persistence of insulation wool fibres and other vitreous silicate fibres. Based on this guideline two Round Robins were conducted as well as specific investigations on the influence of selected test parameters. Nine and six laboratories, respectively, participated in the two Round Robins. The standard deviation between K-dis results obtained by different laboratories was slightly lower in the second Round Robin ranging from 24 to 61 % (highest for the low-soluble fibres). The relatively high inter-laboratory variation suggests that the equipment, setup and procedures should be specified in much more detail in a future test method. Key parameters to be kept constant are flow rate/surface area and liquid composition, and care should be taken to maintain constant conditions and eliminate outlier measurements. A laboratory may use the method described in the guideline for quality assurance of maintained biosolubility and for development of alternative fibre modifications as the method is well suited for ranking different fibres with respect to dissolution coefficients within one laboratory. However, caution should be exercised when comparing values obtained by one laboratory to values obtained by another.