Gravimetric Analysis of the Non-volatile Residue from an Evaporated Droplet, Using the Quartz Crystal Microbalance/Heat Conduction Calorimeter
gravimetrica analysis, non-volatile residue, evaporated droplets
The standard way of determining the non-volatile residue (NVR) in water or an organic solvent is to evaporate a measured quantity of filtered sample solution to dryness and weigh the residue on an analytical balance. This type of gravimetric analysis is fundamental in the fields of water quality, the environment, and the chemical and pharmaceutical industry. The International Standards Organization (ISO) and the American Society of Testing Materials (ASTM) have many published standard gravimetric methods for determining NVR. One example is the recently developed ASTM standard test method F 2459-05 for extracting residue from metallic medical components and quantifying via gravimetric analysis. To determine the NVR at a level of one part per million to a precision of ±10% requires a solvent mass of ~ 100 g with present analytical balances. Evaporation of this amount of solvent is slow and can pose environmental problems. In this session we shall explain how a quartz crystal microbalance/heat conduction calorimeter (QCM/HCC*) can be used to determine the NVR at the parts-per-million level in 10 microliter droplets of methanol and a 45 microliter droplet of water – at least a thousand times less solvent than needed with an analytical balance. The QCM was used to measure the mass of the non-volatile residue, and the calorimeter was used to determine the mass of the solvent by the heat required to evaporate the droplet.
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Nanotech 2006 Conference Program Abstract