High sensitivity analysis of nitrite and nitrate in biological samples by capillary zone electrophoresis with transient isotachophoretic sample stacking

Szökő, Éva; Tábi, Tamás; Halász, A; Pálfi, Melinda; Magyar, K.

doi:10.1016/s0021-9673(04)01198-7

Cited by 15 publications

(7 citation statements)

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“…11,12 Therefore, development a credible and sensitive sensor to detect nitrite in food, drinking water and environmental samples has received continued attention over the past 10 years. Several methods have been developed for nitrite determination, including spectrophotometry, 13,14 chemiluminescence, 15 chromatography, 16,17 capillary electrophoresis 18 and electrochemical methods. [19][20][21][22][23][24][25] Many of these procedures are time-consuming, but the electrochemical technique can provide cheaper, faster and real-time analysis.…”

Section: Introductionmentioning

confidence: 99%

A Simple and Efficient Electrochemical Sensor for Electrocatalytic Reduction of Nitrite Based on Poly(4‐aminoacetanilide) Film Using Carbon Paste Electrode

Ojani

Raoof

Rahemi

2011

J Chinese Chemical Soc

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In this study, the electrochemical reduction of nitrite was investigated on poly(4-aminoacetanilide) (PPAA) forming by cyclic voltammetry at the surface of carbon paste electrode. The electrochemical properties of the modified electrode have been studied by cyclic voltammetry and double potential step chronoamperometry. Results showed that in the optimum condition (pH = 0.00) the reduction of nitrite occurred at a potential about 667 mV more positive than that unmodified carbon paste electrode. This amount of electrocatalytic ability is high compared with other electrocatalysts. Using a chronoamperometric method, the catalytic rate constant (k) was calculated 8.4 × 10 4 cm 3 mol -1 s -1 . Also, the electrocatalytic reduction peak currents was found to be linear with the nitrite concentration in the ranges of 5 × 10 -4 M to 2.5 × 10 -2 M and 2 × 10 -5 M to 7 × 10 -3 M with detection limits (2s) were determined as 4.5 × 10 -4 M and 1 × 10 -5 M by cyclic voltammetry (CV) and hydrodynamic amperometry methods respectively. Recovery experiments exhibit the satisfactory results.

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Section: Introductionmentioning

confidence: 99%

A Simple and Efficient Electrochemical Sensor for Electrocatalytic Reduction of Nitrite Based on Poly(4‐aminoacetanilide) Film Using Carbon Paste Electrode

Ojani

Raoof

Rahemi

2011

J Chinese Chemical Soc

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“…With these regression equations, the LOD of nitrate was determined to be 3.65 µM, and 10.8 µM for nitrite, based on a S/N=3. Previous reports have utilized stacking techniques such as tITP 32;36;45;46 and FASS 36;47 to improve LOD's for both nitrate and nitrite. While this enhancement would be beneficial in quantifying both metabolites, these processes typically employ injecting larger sample plugs into the capillary.…”

Section: No Metabolite Assaymentioning

confidence: 99%

Measurement of Region-Specific Nitrate Levels of the Posterior Chamber of the Rat Eye Using Low-Flow Push−Pull Perfusion

2008

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The determination of the presence of nitric oxide (NO) metabolites in the rat vitreous cavity in a regioselective manner is complicated by the size and shape of the eye as well as the diffusivity of the molecule and its metabolites. In this work, in vivo low-flow push-pull perfusion sampling was utilized with a rapid capillary electrophoretic assay to monitor levels of the major NO metabolite, nitrate, at the vitreoretinal interface (VRI) of normal and aged rat models. The sampling probe tips were placed in three different positions in the posterior chamber through a 29-gauge guide needle. Sampling was performed along the VRI over the optic nerve head and regions peripheral to the optic nerve head. Additionally, samples were collected from the middle vitreous region to compare to VRI sampling. A significant (P<0.05) difference in the perfusate nitrate concentration was observed in each location, which may be due to the source of NO production or the clearance mechanism of the molecule from vitreous cavity. Infusion of L-NAME with physiological saline led to a significant decrease (35%) in the observed nitrate level. LFPPP was then utilized to observe nitrate levels after an average of 4.5 months of aging. A 3-fold increase in the mean level of nitrate over the optic nerve head was observed in mature animals compared to younger control animals. Precise measurement of NO metabolites along the VRI may provide insights into the function of NO in maintaining homeostatic conditions and the molecular changes at the diseased retina.

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“…For slow anions polarity switch can be performed, as the velocity of these ions can exceed that of the EOF (with opposite direction) only in the low-conductivity sample buffer [40,41]. In the case of fast anions, which can be separated in anodic direction at low buffer pH when the EOF is suppressed, no further manipulation other than preparing them in a low-conductivity sample buffer is required [42,43]. However, when an EOF modifier is used, which can either suppress or reverse the EOF, large-volume sample stacking can be performed for all anions [44,45].…”

Section: Large-volume Sample Stackingmentioning

confidence: 99%

Trace analysis of oxidized, nitrated, and chlorinated aromatic amino acids by capillary electrophoresis with electroosmotic flow modification allowing large-volume sample stacking

2005

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A capillary electrophoresis method has been developed for the simultaneous analysis of the oxidized, nitrated, and chlorinated aromatic amino acids, as well as their parent compounds. These modifications of the aromatic amino acids in proteins or free form are induced by the attack of reactive, mainly free radical species generated during cell stress, and these stable products may serve as biomarkers of cell damage. The analytes tyrosine, phenylalanine, dihydroxyphenylalanine, tryptophan, 3-nitrotyrosine, 3-chlorotyrosine, ortho-tyrosine, meta-tyrosine, 3-hydroxyphenylacetic acid (internal standard 1), and alpha-methyltyrosine (internal standard 2) were separated in their anionic forms in alkaline borate buffer. The polyamine spermine was used as electroosmotic flow (EOF) modifier. Adsorbing to the capillary wall, spermine can either suppress or even reverse the EOF depending on its concentration and the pH. The effects of the pH of the separation buffer, the spermine concentration, the temperature, and the applied field strength on the separation were examined. The modified aromatic amino acids are present in biological fluids in a much lower concentration than their parent compounds, thus high detection sensitivity of the analytical method is required. To achieve good detection sensitivity, field-amplified sample stacking of large injection volumes was applied. Omitting polyamine from the sample buffer allowed local reversal of the EOF, thus removal of the low conductivity sample buffer at the capillary inlet. In this way, 100% of the capillary to the detection window could be filled with the sample, and the detection limits achieved for the modified aromatic amino acids were in the range of 2.5-10 nM.

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High sensitivity analysis of nitrite and nitrate in biological samples by capillary zone electrophoresis with transient isotachophoretic sample stacking

Cited by 15 publications

References 0 publications

A Simple and Efficient Electrochemical Sensor for Electrocatalytic Reduction of Nitrite Based on Poly(4‐aminoacetanilide) Film Using Carbon Paste Electrode

A Simple and Efficient Electrochemical Sensor for Electrocatalytic Reduction of Nitrite Based on Poly(4‐aminoacetanilide) Film Using Carbon Paste Electrode

Measurement of Region-Specific Nitrate Levels of the Posterior Chamber of the Rat Eye Using Low-Flow Push−Pull Perfusion

Trace analysis of oxidized, nitrated, and chlorinated aromatic amino acids by capillary electrophoresis with electroosmotic flow modification allowing large-volume sample stacking

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