Validation of a rapid method for detecting nitrate in chard (Beta vulgaris cycla): analysis of Spanish commercial samples marketed in the Region of Huesca, Spain, and estimation of the daily intake
2015
Menal-Puey,Susana | Asensio,Esther
Introduction: This paper presents the validation of a rapid method for the determination of nitrate content in chard samples, in order to determine, during two periods (winter and summer of 2012), the current levels of nitrate in this typical vegetable, and the toxicological risk associated with this intake. Material and Methods: A rapid colorimetric determination of nitrate in chard samples by nitration of salicylic acid was validated. The validated method was applied to analyze the content of nitrate in 56 chard samples marketed in Huesca (Spain) and collected in winter and summer seasons, and the toxicological risk associated with the intake for adult and children population was evaluated. Results: The method was specific and robust enough for the required purposes. The main performance characteristics of the method were: limits of detection and quantitation of 0.29 mg L-1 and 0.59 mg L-1, respectively; recoveries from 80.0% to 107.4%; and coefficients of variation lower than 11.4%. The detected mean nitrate content was 2293 mg kg-1 and there was evidence of risk only for extreme consumers (adults and children), especially in winter period. Conclusions: A high percentage of chard samples with a considerable concentration of nitrate were found. Taking into account the estimated dairy intake of nitrate associated with them, it could be recommended to establish a regulatory limit of nitrate to chard, a vegetable of important consumption in Spain.
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