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Detection method of metaldehyde
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| Principle: |
| The
impurity of metaldehyde product are acetaldehyde, paraldehyde,
water and stabilizing agent. Extract acetaldehyde and paraldehyde in the product by alcohol, then detect the content
of acetaldehyde and the content of paraldehyde in
the extract. |
| Method: |
| First,
weigh up metaldehyde product range from 0.3g to 0.5g(be accurate
to0.0002g)and dump into a little glass flask that could be airproof,
then add one drop 0.1N NaOH solution and 20ml ethanol, and weigh
it, then add 6µl toluene as internal standard with micro
injector, and weigh it, then oscillate the flask in order to
completely extract acetaldehyde, paraldehyde |
| Chromato term: |
| chromato
column:length 30 meters microcolumn
press the column ahead N2:0.04Mpa;
H2:0.03Mpa;Air:0.03Mpa
Vaporization temperature:100 ;detector
temperature:220
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| Column temperature: |
| At
first, maintain 60? for 5 mins ,then raise the temperature from
60 to
80, then
raise the temperature from 80?
to 200at
the speed 20/min
and maintain 200
for 30mins.The setup of the column temperature may be adjusted
in according to the fact
|
| Calculation: |
the
percent of acetaldehyde content =( acetaldehyde peak area /internal
standard peak area)×(internal standard weigh/sample weigh)×2.08
the percent of paraldehyde=(
paraldehyde peak area /internal standard peak area)×(internal
standard weigh/sample weigh)×3.02
remark:2.08 and 3.02 are correction
factors
The percent of metaldehyde content is
that 100 percent minus the percent of acetaldehyde content minus
the percent of paraldehyde content minus the percent
of stabilizing agent content
(metaldehyde)%
=100 — (acetaldehyde)% — (paraldehyde)%
—0.2 remark:
the percent of stabilizing agent content is 0.2%.
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