Dear all,

using a GC-MS, we are re-oxidising the tube when copper is nearly
completely black (we check this regularly) by heating the tube from 650 to
750 °C and connecting to O2/N2 gas ("Protec") for 10-15 minutes, then
cooling down to 650°C (about 30').

This is enough for next about 200 samples (two days, depending on
re-aging). If we have to re-oxidise it every day, we change it completely.
One tube is working in average for about 1000 analysis.
We did not try to re-oxidise it for 12 hours; maybe we would not need to
re-oxidise it all two days. Good idea.

Greetings,
 Deborah
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Deborah Rupprecht
Institute of Plant Nutrition
Karlrobert-Kreiten-Str. 13
53115 Bonn, Germany
Phone (+049) 0228-73-3640, -1631
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