detection method of metaldehyde

Principle:

    The impurity of metaldehyde product are acetaldehyde, trimeric acetaldehyde, water and stabilizing agent. Extract acetaldehyde and trimeric acetaldehyde in the product by alcohol, then detect the content of acetaldehyde and the content of trimeric acetaldehyde 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, trimeric acetaldehyde.

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℃ 

Column temperature：

At first, maintain 60℃ for 5 mins ,then raise the temperature from 60℃ to 80℃, then raise the temperature from 80℃ to 200℃ at 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 trimeric acetaldehyde=( trimeric acetaldehyde 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 trimeric acetaldehyde content minus the percent of stabilizing agent content

 (metaldehyde)% =100 — (acetaldehyde)% — (trimeric acetaldehyde)% —0.2

remark: the percent of stabilizing agent content is 0.2%.