Evaluation of nitrate determination techniques in fresh vegetables: A comparison of spectrophotometric and chromatography methods

Due to the dynamic nature of nitrate in fresh vegetables and the presence of multiple inaccurate detection techniques, quantifying nitrate concentration remains more challenging than detecting other pollutants. This study evaluated the effectiveness of three common methods, namely high-performance l...

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Main Authors: Kobra Sadat Hasheminasab, Meysam Cheraghi, Mostafa Marzi, Karim Shahbazi, Mehdi Beheshti, Ainaz Tavanamehr
Format: Article
Language:English
Published: Elsevier 2025-03-01
Series:Journal of Agriculture and Food Research
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Online Access:http://www.sciencedirect.com/science/article/pii/S2666154325000092
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author Kobra Sadat Hasheminasab
Meysam Cheraghi
Mostafa Marzi
Karim Shahbazi
Mehdi Beheshti
Ainaz Tavanamehr
author_facet Kobra Sadat Hasheminasab
Meysam Cheraghi
Mostafa Marzi
Karim Shahbazi
Mehdi Beheshti
Ainaz Tavanamehr
author_sort Kobra Sadat Hasheminasab
collection DOAJ
description Due to the dynamic nature of nitrate in fresh vegetables and the presence of multiple inaccurate detection techniques, quantifying nitrate concentration remains more challenging than detecting other pollutants. This study evaluated the effectiveness of three common methods, namely high-performance liquid chromatography (HPLC) and two spectrophotometric methods (ISO 6635 and Cadmium-Column Reduction) for measuring nitrate in vegetables. For this purpose, 11 vegetables with varying nitrate accumulation potentials were analyzed. It was observed that the nitrate concentration in onions, as measured by spectrophotometric methods, was lower than the results obtained by HPLC. Consequently, the spectrophotometric methods were modified to improve nitrate measurement in onion samples. The results demonstrated that the average nitrate concentration in leafy vegetables was higher than in tuberous, root, and fruit vegetables. Among the vegetables, spinach, lettuce, and celery, respectively, exhibited the highest nitrate concentrations, while watermelon, tomato, and onion had the lowest levels. A strong correlation was observed across all three methods for determining nitrate content. The HPLC method demonstrated the highest accuracy in samples with high nitrate content, while the spectrophotometric methods were more accurate for samples with low nitrate content. Although the HPLC method incurs higher equipment costs, it is faster, more accurate, and safer than the spectrophotometric methods. Since both Cd-Column reduction and ISO 6635 are based on the Griess reaction, their accuracy depends on factors such as pH, temperature, time, and sample matrix. Therefore, each method can be selected based on laboratory equipment, costs, and specific advantages or limitations.
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spelling doaj-art-95b9bcbd4ce14de28bc48ebbfe9e72502025-08-20T03:04:58ZengElsevierJournal of Agriculture and Food Research2666-15432025-03-011910163810.1016/j.jafr.2025.101638Evaluation of nitrate determination techniques in fresh vegetables: A comparison of spectrophotometric and chromatography methodsKobra Sadat Hasheminasab0Meysam Cheraghi1Mostafa Marzi2Karim Shahbazi3Mehdi Beheshti4Ainaz Tavanamehr5Soil and Water Research Institute (SWRI), Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran; Corresponding author. Soil & Water Research Institute., Imam Khomeini Blvd., Meshkin Dasht Road, Standard Square, Karaj, Iran.Soil and Water Research Institute (SWRI), Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran; Soil Science Department, Faculty of Agriculture, University of Tehran, Karaj, IranSoil and Water Research Institute (SWRI), Agricultural Research, Education and Extension Organization (AREEO), Karaj, IranSoil and Water Research Institute (SWRI), Agricultural Research, Education and Extension Organization (AREEO), Karaj, IranSoil and Water Research Institute (SWRI), Agricultural Research, Education and Extension Organization (AREEO), Karaj, IranSoil and Water Research Institute (SWRI), Agricultural Research, Education and Extension Organization (AREEO), Karaj, IranDue to the dynamic nature of nitrate in fresh vegetables and the presence of multiple inaccurate detection techniques, quantifying nitrate concentration remains more challenging than detecting other pollutants. This study evaluated the effectiveness of three common methods, namely high-performance liquid chromatography (HPLC) and two spectrophotometric methods (ISO 6635 and Cadmium-Column Reduction) for measuring nitrate in vegetables. For this purpose, 11 vegetables with varying nitrate accumulation potentials were analyzed. It was observed that the nitrate concentration in onions, as measured by spectrophotometric methods, was lower than the results obtained by HPLC. Consequently, the spectrophotometric methods were modified to improve nitrate measurement in onion samples. The results demonstrated that the average nitrate concentration in leafy vegetables was higher than in tuberous, root, and fruit vegetables. Among the vegetables, spinach, lettuce, and celery, respectively, exhibited the highest nitrate concentrations, while watermelon, tomato, and onion had the lowest levels. A strong correlation was observed across all three methods for determining nitrate content. The HPLC method demonstrated the highest accuracy in samples with high nitrate content, while the spectrophotometric methods were more accurate for samples with low nitrate content. Although the HPLC method incurs higher equipment costs, it is faster, more accurate, and safer than the spectrophotometric methods. Since both Cd-Column reduction and ISO 6635 are based on the Griess reaction, their accuracy depends on factors such as pH, temperature, time, and sample matrix. Therefore, each method can be selected based on laboratory equipment, costs, and specific advantages or limitations.http://www.sciencedirect.com/science/article/pii/S2666154325000092NitrateVegetablesCadmium-column reductionHPLCISO 6635
spellingShingle Kobra Sadat Hasheminasab
Meysam Cheraghi
Mostafa Marzi
Karim Shahbazi
Mehdi Beheshti
Ainaz Tavanamehr
Evaluation of nitrate determination techniques in fresh vegetables: A comparison of spectrophotometric and chromatography methods
Journal of Agriculture and Food Research
Nitrate
Vegetables
Cadmium-column reduction
HPLC
ISO 6635
title Evaluation of nitrate determination techniques in fresh vegetables: A comparison of spectrophotometric and chromatography methods
title_full Evaluation of nitrate determination techniques in fresh vegetables: A comparison of spectrophotometric and chromatography methods
title_fullStr Evaluation of nitrate determination techniques in fresh vegetables: A comparison of spectrophotometric and chromatography methods
title_full_unstemmed Evaluation of nitrate determination techniques in fresh vegetables: A comparison of spectrophotometric and chromatography methods
title_short Evaluation of nitrate determination techniques in fresh vegetables: A comparison of spectrophotometric and chromatography methods
title_sort evaluation of nitrate determination techniques in fresh vegetables a comparison of spectrophotometric and chromatography methods
topic Nitrate
Vegetables
Cadmium-column reduction
HPLC
ISO 6635
url http://www.sciencedirect.com/science/article/pii/S2666154325000092
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