The safety of mineral wool used for thermal and acoustic insulation must be tested in vivo in case of inhalation before entering the market. Due to the EU's desire and commitment to reduce animal testing, research is focused on in vitro methods that mimic the biological environment. Methods for in vitro determination of solubility and durability of fibres are not standardized, consequently the results between individual research environments and laboratories are not comparable. In this research I determined the influence of individual components in the simulated lung fluid on the solubility of glass. The test was performed on glass chips that replaced the usual wool fibres, which enabled more controlled dissolution of the components in the simulated lung fluid. I determined the concentration of leached ions by using inductively coupled plasma mass spectrometry (ICP-MS).
Samples exposed to solutions containing potassium hydrogen phthalate, sodium citrate and sodium tartrate had the highest solubility in terms of gravimetrically determined mass loss. The concentration of sodium citrate and tartrate that is used in test has fundamental role on the solubility of the fibres. In the salt solutions and the solution with the addition of the amino acid glycine, the samples were poorly soluble, which means that the important components for dissolution in the simulated lung fluid are the organic phase sodium citrate and tartrate. The gravimetrically determined solubility was similar to the solubility determined by measuring the concentration of dissolved ions using the ICP-MS method. A greater change in pH value was observed in solutions with a higher concentration of sodium citrate and tartrate, which caused increased dissolution of the soaked sample. It follows that the choice of buffer is also important when performing the test, since the buffer itself can have a strong influence on dissolution. I compared the organic buffers KHP and MES, whereby the buffer MES had no effect on the dissolution of the sample, while KHP had a significant effect on the dissolution. The phenomenon of supersaturation was observed when dissolving potassium in a solution with ultra purified water and potassium hydrogen phthalate. Precipitation was also observed visually, as a layer of copper color formed on the sample. In this liquid, the largest amount of the sample was dissolved.
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