Determination of Maleic Hydrazide in Potatoes and Onions by Capillary Electrophoresis

A micellar electrokinetic chromatographic method (MEKC) was developed to separate and quantify maleic hydrazide (MH) in potatoes and onions. Methanol was used as the extraction solvent. A 3-mL aliquot of the extract was dried under nitrogen, and the residue was reconstituted in 3-mL of water by sonication. The water fraction was passed through a tC18 solid-phase extraction tube to remove interferences. The last milliliter of the water sample was collected and injected into the capillary electrophoresis (CE) system. Within-day and between-day reproducibility studies run at 2.5, 5.0, 10.0, 15.0, and 20.0 ppm indicated the procedure was reproducible. Potato samples treated with MH were obtained from Aroostock Experimental Farm in Presque Isle, Maine and local supermarkets, while onion samples were purchased from local stores. A comparison was made between CE and a high performance liquid chromatography (HPLC) method. The linear regression for maleic hydrazide was y = 0.816x + 1.071 with a correlation coefficient of 0.878. Detection limit was 2.0 ppm. Keywords: Environmental analysis; maleic hydrazide; pesticides; capillary electrophoresis