Modified QuEChERS for the Analysis of Chlorothalonil
A modified version of the QuEChERS-Method for the analysis of Chlorothalonil residues in various crops, including crops posing difficulties in the analysis of this compound (e.g. brassica nad leek family crops), is presented.
The method involves acidification of the sample with sulphuric acid to pH~1 at the very beginning of the procedure to prevent any degradation upon reaction with sample components. No buffer salts are used in the initial extraction/partitioning step and no dispersive-SPE cleanup is performed. Determinative analysis is performed via GC-MSD or LC-MS/MS in the APCI neg. mode. In the LC-MS/MS ion source (APCI-neg. mode) chlorothalonil undergoes hydrolytic dechlorination to 4-hydroxy-chlorothalonil that forms the parent ion. Any 4-hydroxy-chlorothalonil present in the sample can also be determined separately with the same method giving the same mass transitions but a peak at a different retention time. The stability of extracts was studied over 9 days and was shown to be highly satisfactory.
- Modified QuEChERS for the Analysis of Chlorothalonil: Click here
- Methods provided by EURL-SRM (overview): Click here
Published 04-04-2011, 11:37:36
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