Certification of nitrate in spinach powder reference material SPIN-1 by high-precision isotope dilution GC–MS

Meija, Juris; Campanella, Beatrice; Onor, Massimo; Iammarino, Marco; D’Amore, Teresa; Berardi, Giovanna; D’Imperio, Massimiliano; Parente, Angelo; Mihai, Ovidiu; Mester, Zoltán

doi:10.1007/s00216-019-01803-4

Cited by 12 publications

(5 citation statements)

References 30 publications

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“…Both analytical methods were fully validated according to the most representative references and guidelines [ 32 , 39 , 40 , 41 , 42 , 43 , 44 ], accredited by the Italian Body for Laboratory Accreditation ACCREDIA, submitted to annual proficiency test round, and routinely adopted for the official control of nitrite and nitrate in food. It is worth mentioning that both techniques were employed within the certification procedure of a reference material (nitrate in spinach powder), in 2018–2019 [ 45 ]. The most important validation parameters that characterize the two analytical methods used in this monitoring are summarized in Table 1 [ 30 , 34 ].…”

Section: Methodsmentioning

confidence: 99%

Determination of Nitrate and Nitrite in Swiss Chard (Beta vulgaris L. subsp. vulgaris) and Wild Rocket (Diplotaxis tenuifolia (L.) DC.) and Food Safety Evaluations

Iammarino

Berardi

Vita

et al. 2022

Foods

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Nitrite and nitrate levels in vegetables are a matter of concern due to their toxicity at high levels and nitrate high accumulation. Moreover, there is a lack of knowledge about their levels in some types of widely consumed vegetables such as chard and rocket. In this study, 124 Swiss chard and wild rocket samples were analyzed for determining nitrite and nitrate using validated and accredited analytical methods by ion chromatography with conductivity detection. High nitrite concentrations, up to 219.5 mg kg−1 f.w., were detected in one Swiss chard and three wild rocket samples. One Margin of Safety (MoS) value was <1. Regarding nitrate, in Swiss chard samples the mean concentration (2522.6 mg kg−1) was slightly higher than those reported in the literature for spinach and lettuce. No MoS was <1, but 83% of values were <100. Nitrate concentrations higher than the legal limit were quantified in 11 rucola samples. The verification of 25% of wild rocket samples with nitrate concentration higher than the legal limit confirmed the need for official control. This study also suggests the introduction of legal limits for nitrite/nitrate in Swiss chard and nitrite in wild rocket.

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Section: Methodsmentioning

confidence: 99%

Determination of Nitrate and Nitrite in Swiss Chard (Beta vulgaris L. subsp. vulgaris) and Wild Rocket (Diplotaxis tenuifolia (L.) DC.) and Food Safety Evaluations

Iammarino

Berardi

Vita

et al. 2022

Foods

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“…All mathematical models for the calculation of the analytical results and the uncertainties are reported in the ESM. Briefly, nitrate results were obtained by exact matching quadruple isotope dilution following triethyloxonium derivatization [ 43 , 50 , 51 ], and the corresponding uncertainty was calculated by error propagation (see Paragraph S1.11 [ 52 ]). For the determination of phosphate and silicate, external calibration using standards prepared in a matrix-matched medium (low-nutrient seawater, OSIL) was employed.…”

Section: Resultsmentioning

confidence: 99%

From sea salt to seawater: a novel approach for the production of water CRMs

et al. 2022

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Natural water certified reference materials (CRMs) are mostly available in a liquid form, and they are produced starting from suitable environmental samples. Many precautions are usually needed to avoid biological or physical degradation, including filtration, acidification, and sterilization. In this study, the drawbacks associated with liquid-based seawater CRMs were tackled by developing a salt-based seawater proxy for nutrients that could be reconstituted in water solution just before use. Phosphate, silicate, and nitrate were chosen as target analytes. Sea salt mimicking the composition of seawater was spiked with an aqueous solution of the analytes and homogenized using a high-energy planetary ball mill (uhom < 1.2%). The salt powder CRM SALT-1 (https://doi.org/10.4224/crm.2022.salt-1) demonstrated good short- and long-term stability for nutrients. When the SALT-1 was reconstituted in water at the 4.0% w/w level, the resulting solution had similar properties with respect to typical seawater in terms of major constituents (± 20%), trace metals, density (1.023 g/mL), pH (8.8–9.0), and optical properties relevant to the photometric characterization. Phosphate and silicate were quantified by photometry (molybdenum blue method, batch mode), whereas nitrate was quantified by isotope dilution GC−MS (uchar < 1.2%). In the SALT-1 reconstituted seawater solution at the 4.0% w/w salt level, the nutrient amount concentration was w(phosphate, PO43−) = 1.615 ± 0.030 μmol/L, w(silicate as SiO2) = 8.89 ± 0.31 μmol/L, and w(nitrate, NO3−) = 18.98 ± 0.45 μmol/L at the 95% confidence (k = 2). Overall, the SALT-1 CRM exhibits similar nutrient profile and general analytical characteristics as the MOOS-3 CRM. However, the SALT-1 has much reduced preparation, storage, and distribution cost, likely much better long-term stability, and it could enable the production of lower cost and more accessible seawater reference materials. Graphical abstract

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“…Consider the certification of nitrate ions in the NRC spinach powder reference material SPIN-1 [24]. The NO − 3 content in this CRM was assigned by high-precision isotope dilution to w(NO − 3 ) = (22.53 ± 0.43) mg g −1 [25]. During the certification campaign, ion-chromatography coupled with conductivity detection was used as an additional measurement method.…”

Section: Nitrates In Spinachmentioning

confidence: 99%

Calibration model averaging in chemical analysis: a case study for the method of standard additions

Meija

2023

Metrologia

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In this study we demonstrate that the method of standard additions can provide unreliable results in chemical analysis when linear calibration model is forced to fit the data. A well designed standard addition experiment can still yield results biased by 10 % when the analyst relies only on linear model.Recently, the Joint Committee for Guides in Metrology (GUM-6) has emphasized the need to address the uncertainty inherent to the choice of measurement models and here we show how model averaging can provide a practical way to account for model uncertainty in the method of standard additions.

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Certification of nitrate in spinach powder reference material SPIN-1 by high-precision isotope dilution GC–MS

Cited by 12 publications

References 30 publications

Determination of Nitrate and Nitrite in Swiss Chard (Beta vulgaris L. subsp. vulgaris) and Wild Rocket (Diplotaxis tenuifolia (L.) DC.) and Food Safety Evaluations

Determination of Nitrate and Nitrite in Swiss Chard (Beta vulgaris L. subsp. vulgaris) and Wild Rocket (Diplotaxis tenuifolia (L.) DC.) and Food Safety Evaluations

From sea salt to seawater: a novel approach for the production of water CRMs

Calibration model averaging in chemical analysis: a case study for the method of standard additions

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Certification of nitrate in spinach powder reference material SPIN-1 by high-precision isotope dilution GC–MS

Cited by 12 publications

References 30 publications

Determination of Nitrate and Nitrite in Swiss Chard (Beta vulgaris L. subsp. vulgaris) and Wild Rocket (Diplotaxis tenuifolia (L.) DC.) and Food Safety Evaluations

Determination of Nitrate and Nitrite in Swiss Chard (Beta vulgaris L. subsp. vulgaris) and Wild Rocket (Diplotaxis tenuifolia (L.) DC.) and Food Safety Evaluations

From sea salt to seawater: a novel approach for the production of water CRMs﻿

Calibration model averaging in chemical analysis: a case study for the method of standard additions

Contact Info

Product

Resources

About

From sea salt to seawater: a novel approach for the production of water CRMs