- 1.1 Issue Description
- 1.2 Possible Root Cause
- 1.3 Diagnostic
- 1.4 Symptoms Solving
- 1.5 Root Cause Solving
- 1.6 How to Prevent Future Issues
2 Appendix

This Article is valid for the following devices and version:

EA
AGE3

Issue Description

Occasionally, graphitization fails, producing irregular or erratic pressure curves. In some reactors the reaction may not occur at all (see Appendix examples).

Possible Root Cause

This failure is often linked to sulfur in the samples introduced to the EA. Combusting sulfur‑ containing samples in an elemental analyzer poisons the iron catalyst, diminishing its ability to promote graphitization.

→ Sulfur reacts with iron in the reactors to form iron sulfide, which inhibits the catalytic graphite reaction. After a failed run, the powder may exhibit a metallic “fool’s‑gold” sheen – a clear indication of iron‑sulfide formation.

Diagnostic

Check if the silver wool in the EA columns is tarnished.

→ Silver wool tarnishes when exposed to air containing sulphur, making silver wool look yellowish.

Symptoms Solving

Remove the sulphur contamination from your EA-AGE lines as much as possible before processing new samples. For this, follow these measures:

In EA:
1. Completely replace the reduction and combustion tubes with new ones, and also use fresh refill materials (copper, silver wool, aluminium oxide wool, corundum balls, etc.).
2. Afterwards, perform as many RunIns as needed until your TCD unit curve shows a flat C curve (the C peak should be less than 2 TCD units high).
3. Make use of the “Heat-out column” option to further clean the adsorption column and repeat a bunch of RunIns afterwards until you get a flat C curve again.
In AGE:
1. Clean the trap several times sequentially, by clicking on “Clean” at the Trap command in AGE software, ensuring that the valve V7 is set to venting in the meantime.
2. Clean the reactor lines as well as the connecting lines between the trap and the reactors:
  1. place empty reaction tubes in all reactors.
  2. connect the reactors to the vacuum line to set them under vacuum (i.e. vac/vent valve is set to vacuum).
  3. set the temperatures of the ovens to 500 °C.
  4. once the oven reaches the desired temperature, rise the ovens (clicking the Up/Down button in AGE software) to heat the reaction volumes while being evacuated.
  5. with the ovens still risen, vacuum and vent the reactors several times. Wait a couple of minutes between each cycle.

Root Cause Solving

Do not process samples containing sulphur in AGE.

How to Prevent Future Issues

When possible, avoid processing samples containing sulphur in EA and AGE.
Check and replace silver wool regularly.