Microcoulometry

Chlorine Coulometry

When a Chloride containing sample is combusted at 1000 ℃, Hydrogen Chloride is formed (HX):

R-X + O2 --> HX + CO2 + H2O

The combustion gas, carrying halide ions, is led into a sulfuric acid scrubber for rapid water and interference removal. The dried and clean gas is led into the temperature controlled titration cell, where the halide ions
react with silver ions, present in the titration cell. The amount of charge (the integral of the regeneration current over the measuring time) used to regenerate the lost silver ions, is directly related to the Total Chloride (TX) content of the sample.

The equations for this reaction are:

HX + Ag+ --> H+ + AgX
Ag --> Ag+ + e

Sulfur Coulometry

When a Sulfur containing sample is combusted at 1000 ℃, Sulfur dioxide is formed SO2:

R-S + O2 --> SO2 + CO2 + H2O

The combustion gas, carrying Sulfur dioxide (SO2), is led into a sulfuric acid scrubber for rapid water and interference removal. The dried and clean gas is led into the temperature controlled titration cell, where the Sulfur dioxide reacts with Tri-iodine, present in the titration cell. The amount of charge (the integral of the regeneration current over the measuring time) used to regenerate the lost Tri-iodine, is directly related to the Total Sulfur content of the sample.

The equations for this reaction are:

SO2 + I3- + H2O --> SO42- + 3 I- + 4 H3O+
2 I- --> I2 + 2 e
I2 + I- --> I3-

• Elemental combustion analyzers that make use of these detection technique(s): Xplorer-TX, Xplorer-TS, Xplorer-TX/TS

International methods carried out by using microcoulometry (TX): ASTM D4929, ASTM D5194, ASTM D5808, ASTM D6721, ASTM D7457, GB-T 18612, UOP 779,

International methods carried out by using microcoulometry (TS): ASTM D3246, ASTM D3120, ASTM D3961, GBT 11061, SH/T 0253