Example of Analysis of Chlorine-Based Agricultural Chemicals in Cabbage by the Backflush System
Residual agricultural chemicals in farm produce are potentially harmful to the human body. For this reason, residual criteria values are laid down by the type of crop and component in accordance with the regulations of each country. In food analysis, sample blanks contain lots of components, which tend to increase the time required for analysis. This analysis time, however, can be considerably shortened by performing backflush.
The page presents an example wherein backflush analysis helps reduce the analysis time to less than half the time required for complete elution of all sample components.
Chromatograms of cabbage extract and sample made by adding eight chlorine-based agricultural chemical standard samples to cabbage extract
(analysis by GC-ECD)
(α-BHC, β-BHC,γ-BHC,δ-BHC, P.P‘-DDE, O,P’-DDT, P,P’-DDD, P,P’-DDT, 0.1 µg/mL each)
Complete elution of all sample components requires 32 minutes to elute the high-boiling-point components contained in cabbage. If the component to be analyzed is BHC, for example, setting the backflush to 12 minutes after elution of BHC completes backflush analysis in 15 minutes. This reduces the analysis time to less than half the time for regular analysis.
A blank run was subsequently performed to confirm that no residual blank components remain in the column.
The chromatogram below shows the results of quintuplicate backflush analysis. High repeatability was achieved. The results confirm that no residual blank components from the cabbage remain in the column.
As shown above, backflush analysis reduces analysis time and prevents retention of blank components in the column. It also prevents deterioration of the column and shifts in retention time.
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