New analysis method

This week, after many months of preparations, we have performed the first test of a new analysis method. The main step? Burning the dust-laden filters!

Our new muffle furnace with some filters ready to burn! The filters (or rather, a small part of them) are inside those small crucibles.

Of course, it’s a bit more complex than just using a match. The filters are special ashless ones, and are put inside quite small crucibles in a muffle furnace at a very stable high temperature during a very specific amount of time. This completely removes the filter, leaving us with just the mineral dust sample. This sample is then weighted in a high precision balance, so we can obtain those magic μg/m³ numbers we quote in the papers (ok, we also need to know the amount of air that went through to the filter, but this is something our samplers can reliably provide). After the weighting, the dust sample is stored for the analysis of its composition at a later date.

Weighting the dust sample (placed inside a small crucible) after it went through the furnace.

But hold on, because before all that, we remove the soluble part of the sample for its later analysis. For that, we “wash” the filters with very pure water inside special sample holders. These holders are later put in a centrifuge so that the water plus the soluble part completely comes out of the filter.

Washing the filter to remove the soluble part of the dust sample.
Our new centrifuge being loaded with the first samples.

All in all, despite its apparent simplicity, this is a rather elaborate method which involves a lot of equipment (some of it, designed by us) and many steps. So, although there are still a ton of details to iron, we’re quite happy to have carried out the first full test — specially because the results were quite good and we didn’t burn down the house!