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Description
Reliable evaluation of extraction efficiency is essential for the development of analytical procedures for pesticide residue determination in water. This study compares the applicability of three previously validated RP-HPLC methods for assessing the efficiency of liquid–liquid extraction (LLE) of 2,4-dichlorophenoxyacetic acid (2,4-D), atrazine, malathion, fenitrothion and parathion from water samples.
Fortified distilled water samples containing selected pesticides at three concentration levels were subjected to LLE using dichloromethane, diethyl ether, petroleum benzine and a mixture of n-hexane and acetone (4:1, V/V). The extracts were analyzed using three validated RP-HPLC methods1,2 employing RP-8 columns of different dimensions under optimized isocratic chromatographic conditions.
All three methods provided satisfactory separation of the investigated pesticides, with resolution values for the closest eluting peaks exceeding 1.5. Although the shortest column reduced the analysis time from approximately 10 to 4 min, it maintained chromatographic performance and analytical sensitivity comparable to those of the longer columns. Furthermore, all three methods provided similar recovery values and identical ranking of extraction solvent efficiency, identifying dichloromethane as the most efficient solvent, followed by diethyl ether, n-hexane/acetone (4:1, V/V) and petroleum benzine.
The results demonstrate that all three validated RP-HPLC methods are suitable for evaluating LLE efficiency. Their consistent analytical performance confirms the reliability of the proposed approach, while the shortest RP-8 column offers a practical advantage for routine analysis owing to its substantially shorter analysis time.