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Coulometric methods measure carbon content converting carbon to CO₂.

The combustion to CO₂ takes place in an electrically heated tube furnace at 1000°C. Complete combustion is guaranteed by using a catalyst mixture.

The chloride content is determined by potentiometric titration of the substance dissolved in NaOH (total chloride content). 5g silica is dissolved by warming in a 400 ml beaker to which 100 ml NaOH solution is added (5 g NaOH, diluted with 100 ml water). The cooled sodium silicate solution is poured while stirring into a similarly sold nitric acid solution (75 ml, 2 molar).

Approx. 2 - 5 g precipitated silica or 1 g AEROSIL fumed silica is weighed into a weighing bottle with a ground lid, which has been dried at 105°C and is dried for two hours in the drying oven at 105°C. After replacing the lid and cooling in a desiccator, the loss of weight is measured.

A fully automatic device where only the filling of the sample amount in the quartz crucible is done manually is described in OENORM G 1074. However, it does not correspond to the devices used in ISO 787/2, thus it is mainly relative measurements which are carried out. The same applies for measuring equipment where the drying is carried out with infrared lamps.

Ignition loss, at 1000°C, measures moisture and other components.

Precautionary measures must be taken to avoid dust forming. After cooling in the dessicator, the loss of weight is determined. For calculating the ignition loss which is based on the substance dried for two hours at 105°C, four analyzed drying losses must be available.