Determination of nitrate in unfiltered extracts of muskmelon tissue by ion‐selective electrodes

Abstract

Nitrate (NO₃‐N) determination with ion‐selective electrodes (ISE) on muskmelon (Cucumis melo L.) leaf petiole tissue was equivalent to the cadmium (Cd) reduction method provided that the aluminum sulfate [Al₂(SO₄)₃] buffer solution was >0.04M to eliminate ionic strength effects from varying NO₃ and chloride (Cl) concentrations. Recovery of added NO₃ was better with the HACH ISE, 98.8%, as compared with Orion ISE, 93.6%. The addition of silver sulfate (Ag₂SO₄) did not significantly improve NO₃ recovery with either ISE. The addition of carbon depressed the detected NO₃ concentration by 9.7%. The HACH ISE offers the advantage of a inexpensive, easy‐to‐use, single body electrode with a durable membrane allowing the filtration step to be eliminated.