Milestone DMA-80 evo - 8.6.3 How to work with difficult matrices

Milestone Srl MA213-003 – DMA-80 EVO – User Manual
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8.6.2 How to increase the recovery of difficult samples
It is possible with the DMA-80 unit to increase the recovery from difficult inorganic sample matrices, such
as metal oxide, by increasing its decomposition temperature and time.
Matrix
Sample
Program
Recovery
ZnO
100 mg (size
100 um)
1.Max START Temp. 200°C, Drying/Ashing 2
min up to 650°C, 2 min at 650°C
60%
2. Max START Temp. 200°C, Drying/Ashing
200°C, 3 min up to 750°C, 2 min at 750°C
100.5%
MnO
100 mg (size
100 um)
1.Max START Temp. 200°C, Drying/Ashing 2
min up to 650°C, 2 min at 650°C
50 %
2. Max START Temp. 200°C, Drying/Ashing
200°C, 3 min up to 750°C, 2 min at 750°C
99.9 %
8.6.3 How to work with difficult matrices
Difficult matrices such as petrochemical products, samples containing solvent, or large amounts (> 100 mg)
of organic sample (blood , food, feed, agricultural sample, etc.) can explode without warning, and
consequently reduce the sensitivity of the system.
For serious problems, and when it is difficult to determine whether the catalyst or amalgamator is the source
of reduced sensitivity, we recommend replacing both of them.
Dedicated programs must be used for difficult matrices.
Matrix
Sample
Program
Tips and tricks
Petrochemical
products and
samples
containing
solvent
Low reactivity
20-50 mg
Max START Temp. 200°C,
Drying/Ashing
1min at 200°C,
3 min up to 800°C,
1 min at 8000°C
Reduce the drying
temperature and
extend
the time if strong
exothermic reaction
persists
Use pre-concentration
step to increase
signal of low Hg amount
High reactivity
10-20 mg
Food, feed,
Agriculture
High reactivity
50 mg
Low reactivity
100 mg (i.e.
fresh vegetable)
Food
containing oil
100 mg
Longer drying step allows a pre-
combustion of sample before rapid decomposition at high temperature,
reducing the exothermic reaction.