Sequential Injection Determination of Nitrate in Vegetables by Spectrophotometry with Inline Cadmium Reduction

Oliveira, Sara M.; Lopes, Teresa I. M. S.; Rangel, António O.S.S.

doi:10.1080/00103620601174635

Cited by 8 publications

(5 citation statements)

References 21 publications

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“…Enhanced electron transport may occur given the lower electrical resistivity (r) of Cd (r ¼ 6.84 Â 10 À8 U m) than Fe (r ¼ 9.58 Â 10 À8 U m). Second, if Cd(II) is reduced to Cd(0), it can reduce nitrate to nitrite (Alonso et al, 1998;Wang et al, 1998;Oliveira et al, 2007), which may lead to an increased nitrite yield ratio (defined as [nitrite] final / [nitrate] initial ). Nitrite tends to accumulate under strongly alkaline conditions created by nitrate reduction (Guy et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

Simultaneous removal of cadmium and nitrate in aqueous media by nanoscale zerovalent iron (nZVI) and Au doped nZVI particles

et al. 2014

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a b s t r a c tNanoscale zerovalent iron (nZVI) has demonstrated high efficacy for treating nitrate or cadmium (Cd) contamination, but its efficiency for simultaneous removal of nitrate and Cd has not been investigated. This study evaluated the reactivity of nZVI to the cocontaminants and by-product formation, employed different catalysts to reduce nitrite yield from nitrate, and examined the transformation of nZVI after reaction. Nitrate reduction resulted in high solution pH, negatively charged surface of nZVI, formation of Fe 3 O 4 (a stable transformation of nZVI), and no release of ionic iron. Increased pH and negative charge contributed to significant increase in Cd(II) removal capacity (from 40 mg/g to 188 mg/g) with nitrate present. In addition, nitrate reduction by nZVI could be catalyzed by Cd(II): while 30% of nitrate was reduced by nZVI within 2 h in the absence of Cd(II), complete nitrate reduction was observed in the presence of 40 mg-Cd/L due to the formation of Cd islands (Cd(0) and CdO) on the nZVI particles. While nitrate was reduced mostly to ammonium when Cd(II) was not present or at Cd(II) concentrations ! 40 mg/L, up to 20% of the initial nitrate was reduced to nitrite at Cd(II) concentrations < 40 mg/L. Among nZVI particles doped with 1 wt. % Cu, Ag, or Au, nZVI deposited with 1 wt. % Au reduced nitrite yield to less than 3% of the initial nitrate, while maintaining a high Cd(II) removal capacity.© 2014 Elsevier Ltd. All rights reserved. Available online at www.sciencedirect.com ScienceDirect journal homepage: www.else vier.com/locate /wa tres w a t e r r e s e a r c h 6 3 ( 2 0 1 4 ) 1 0 2 e1 1 1http://dx

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Section: Introductionmentioning

confidence: 99%

Simultaneous removal of cadmium and nitrate in aqueous media by nanoscale zerovalent iron (nZVI) and Au doped nZVI particles

et al. 2014

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“…After filtering through a 0.2-mm polyvinylidene fluoride membrane (Millipore; www.millipore.com), the extracted NO 3 2 was reduced inline to NO 2 2 in a copperized cadmium column and determined as NO 2 2 . According to the Griess-Ilosvay reaction, NO 2 2 is diazotized with sulfanilamide and coupled with N-(1-naphthyl)-ethylenediamine dihydrochloride to form a purple-red azo dye monitored at 538 nm (Oliveira et al, 2007). NH 4 + was measured according to Andrew et al (1995).…”

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confidence: 99%

The Mitochondrial Folylpolyglutamate Synthetase Gene Is Required for Nitrogen Utilization during Early Seedling Development in Arabidopsis

et al. 2012

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Investigations into the biochemical processes and regulatory mechanisms of nitrogen (N) utilization can aid in understanding how N is used efficiently in plants. This report describes a deficiency in N utilization in an Arabidopsis (Arabidopsis thaliana) transfer DNA insertion mutant of the mitochondrial folylpolyglutamate synthetase gene DFC, which catalyzes the conjugation of glutamate residues to the tetrahydrofolate during folate synthesis. The mutant seedlings displayed several metabolic changes that are typical of plant responses to low-N stress, including increased levels of starch and anthocyanin synthesis as well as decreased levels of soluble protein and free amino acid, as compared with those in wild-type seedlings when external N was sufficient. More striking changes were observed when dfc seedlings were grown under N-limited conditions, including shorter primary roots, fewer lateral roots, higher levels of glycine and carbon-N ratios, and lower N content than those in wild-type seedlings. Gene expression studies in mutant seedlings revealed altered transcript levels of several genes involved in folate biosynthesis and N metabolism. The biochemical and metabolic changes also suggested that N assimilation is drastically perturbed due to a loss of DFC function. The observation that elevated CO 2 partly rescued the dfc phenotypes suggests that the alterations in N metabolism in dfc may be mainly due to a defect in photorespiration. These results indicate that DFC is required for N utilization in Arabidopsis and provide new insight into a potential interaction between folate and N metabolism. Nitrogen (N) is an essential macronutrient for plants and a major limiting factor for crop growth (Diaz et al., 2006). Investigations into the biochemical processes and regulatory mechanisms of N utilization can aid in understanding how N is used efficiently in plants. Low inorganic N results in numerous perturbations in plant metabolism, such as decreases in nitrate (NO 3 2

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“…Most authors describe the spectrophotometric determination of nitrite based on a colorimetric reaction and then present either the concentration of nitrite, [6][7][8] or the concentration of both nitrate and nitrite after reduction of nitrate. 9,10 Another spectrophotometric approach was described by Mikuska, 11 replacing the traditional colorimetric reaction for chemiluminescent detection. There were also a few works using electrochemical detection systems, such as potentiometry 12 and voltammetry.…”

Section: Introductionmentioning

confidence: 99%

Development of a sequential injection system for the determination of nitrite and nitrate in waters with different salinity: Application to estuaries in NW Portugal

et al. 2009

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In this work, a sequential injection methodology for monitoring nitrite and nitrate in estuarine waters without any previous treatment is described. The developed system was applied to the measurement of nitrite and nitrate in estuarine waters of three rivers in the NW Portugal, allowing an automatic, fast (ca 60 h À1 ) and precise method (relative standard deviation lower than 2%). The procedure was based on the reaction between nitrite, sulfanilamide and N-(1-naphthyl)-ethylenediamine dihydrochloride (N1NED), whereas the determination of nitrate resulted from its reduction to nitrite, using an in-line cadmium column, followed by the same reaction. The samples were collected in three locations for each river (Douro, C avado and Ave) covering the lower, middle and upper section of the estuaries. Despite the presence of a salinity gradient, this parameter showed no interference in the accuracy of the determinations. The results obtained for the described method for nitrite were statistically comparable to those obtained by the reference procedure. For the determination of nitrate, recovery tests confirmed that the sequential injection methodology provided good quality results.

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Sequential Injection Determination of Nitrate in Vegetables by Spectrophotometry with Inline Cadmium Reduction

Cited by 8 publications

References 21 publications

Simultaneous removal of cadmium and nitrate in aqueous media by nanoscale zerovalent iron (nZVI) and Au doped nZVI particles

Simultaneous removal of cadmium and nitrate in aqueous media by nanoscale zerovalent iron (nZVI) and Au doped nZVI particles

The Mitochondrial Folylpolyglutamate Synthetase Gene Is Required for Nitrogen Utilization during Early Seedling Development in Arabidopsis

Development of a sequential injection system for the determination of nitrite and nitrate in waters with different salinity: Application to estuaries in NW Portugal

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