Method For Analysis Of Nitrate Research Articles

Determination and validation of simultaneous derivatization and dispersive liquid‐liquid microextraction method for analysis of nitrate and nitrite contents as nitrate ions in onion and potato samples

AbstractA simple and rapid method has been developed for the extraction of nitrate and nitrite from potato and onion samples using derivatization dispersive liquid‐liquid microextraction coupled with high‐performance liquid chromatography with ultraviolet detection. In this process nitrate ions are derivatized to 2,4‐dimethyl‐6‐nitrophenol using 2,4‐dimethyl phenol (as a derivatization agent) and the derivatized compound is concentrated using the microextraction method. The nitrite in the samples is rapidly oxidized to nitrate with potassium permanganate. After derivatization of nitrate ions under an acidic medium, the derivatized compound is extracted into carbon tetrachloride (as an extraction solvent) in the presence of methanol (as a dispersive solvent). Under optimum conditions, calibration graph was linear in the range of 31–50 000 ng/mL with r2 = 0.9997. The limits of detection and quantification were 9.1 and 31 ng/g, respectively. Extraction recovery was found to be 90%. Lastly, some real samples were analyzed and nitrite and nitrate contents were successfully determined. The developed method was compared with ISO 3365 method and the results showed that the proposed method is more efficient than it.

Rapid and sensitive method for analysis of nitrate in meat samples using ultra performance liquid chromatography–mass spectrometry

A sensitive and selective ultra performance liquid chromatography–mass spectrometric method has been developed for the quantitative analysis of nitrate in meat samples. Selected ion reaction (SIR) mode was adopted to identify and quantify the nitrate. Chromatographic analyses were performed on a BEH C-18 column with a mobile phase consisting of a surfactant (Cetylpyridinium chloride) and acetonitrile in equal ratio (50/50, v/v) at a flow rate of 0.4mLmin−1. The limit of detection and limit of quantitation of the developed method was found to be 0.0599 and 0.1817mgkg−1, respectively. The linearity of the proposed method was checked in the concentration range of 0.5–10mgkg−1 with an excellent correlation coefficient (r) of 0.997. The recovery of the nitrate in the meat samples were in the range of 98.02–98.99%.

An ultra performance liquid chromatography-electrospray ionization-mass spectrometry method for the rapid analysis of nitrate in drinking water

Excess of nutrient load can cause water eutrophication and be harmful to humans. While nitrogen is an important nutrient for crops, its introduction into the soil with fertilizers containing nitrate (NO3−) has been a major source of water pollution and monitoring NO3− has become necessary. In the present work, an ultra performance liquid chromatography-mass spectrometry method has been developed for the rapid quantification of NO3− in drinking water with reversed phase chromatography using a Waters Acquity BEH C18 (50 mm × 2.1 mm i.d., 1.7 μm particle size) column and a triple quadrupole mass spectrometer operating in Single Ion Recording mode. The quality parameters of the developed method were established, obtaining a limit of detection of 0.02 μg L−1; linearity (r2 > 0.999) over a concentration range covering 3 orders of magnitude; high precision, with repeatability and reproducibility lower than 3% (n = 5) in terms of relative standard deviation when analyzing a standard (0.05 mg NO3− L−1) and unspiked drinking water samples with levels of NO3− of 1 μg L−1 (metropolitan water) and 3 mg L−1 (bottled water). These quality parameters show that the proposed method improves the performance of conventional analytical methods used for the analysis of NO3−. This method has been applied successfully for determination of NO3− in metropolitan and bottled water from the Kingdom of Saudi Arabia; a total of 25 samples have been analyzed where NO3− was found to be present from levels below the limit of detection to 6.49 mg L−1.

Pretreatment Method for Nitrogen Isotopic Analysis of Nitrate in Seawater

A suitable method for the pretreutment of dissolved nitrate samples in seawaters for nitrogen isotopic analysis was established. First, the seawater samples were processed by removing nitrite and amonium. Then Devard's alloy was added in sample for conversion of dissolved nitrate to ammonium. The sample was distilled, and then the ammonium condensate was collected with zeolite. after distillation, the collected condensate was filtered and prepared for determining nitropic values. Some tests of the method were conducted. The distillation condition, the influence of salinity on nitrogen isotopic analysis, absorption of ammonium onto zeolite and an improved method on a large volume of seawater were discussed in this study. The results showed that the distillation step had an average recovery of (104.9 +/- 4.2) % (n = 6) when distillating every 300 mL aliquot of the sample under a strong alkaline condition with 0.5 g devard's alloy and a distillation time of 30 min. The nitrogen isotopic fractionation decreased markedly when salinity was increased from 0% to 0.5%; further increase(1% - 3.5%) showed little effect. The adsorption rate of ammonium onto zeolite had a high yield of (95.96 +/- 1.08) % (n = 6) in average. An improved collection method was used to process a large volume of seawater with several distillations, and had good effect on analysis. The method had been applied to analyze water samples collected from Changjiang estuary. The analytical results indicate that the method is suitable for delta(15)N analysis of dissolved nitrate in seawaters. The present method could provide valuable information about the source and cycle mechanism of dissolved nitrogen in estuary waters.

Revisiting nutrient utilization in the glacial Antarctic: Evidence from a new method for diatom‐bound N isotopic analysis

Isotopic measurements of diatom‐bound nitrogen, using a wet chemical oxidation combined with the “denitrifier” method for nitrate analysis, show significant offsets from previously published combustion‐based measurements. This offset is attributed to a gaseous nitrogen blank associated with the diatom's opal frustule. Moreover, experimentation with multiple chemical cleaning protocols demonstrates that diatom microfossils from the clay‐rich sediments of the glacial Antarctic are more difficult to clean than Holocene materials. New downcore profiles from the Antarctic show no change in the diatom‐bound N 15N/14N between the last glacial and the Holocene in the Atlantic sector, and the elevation of glacial diatom‐bound 15N/14N relative to the Holocene in the Indian sector is smaller than in previous measurements. These data suggest no change in the degree of nitrate utilization in the Atlantic sector and at most a 20% increase (from ∼25 to 45%) in the Indian sector. The new measurements suggest that, during the last ice age in the Atlantic sector of the Antarctic, the atmospheric source of biologically available iron was not so great as to become significant relative to the iron supply from below. Given the apparent spatial variability in the degree of nitrate drawdown, more work is required to develop an adequate picture of the glacial Antarctic nutrient field.

Simplified version of the sodium salicylate method for analysis of nitrate in drinking waters

The salicylate method for determination of nitrate in drinking waters has been simplified by using the calibration solutions for 54 days, and therefore, reducing the work time. The results obtained can be considered satisfactory with regard to limit of determination (0.10 mg l −1 nitrate as nitrogen (NO 3 −-N)), precision (relative standard deviations <4% for five determinations were found) and accuracy (recoveries from 88 to 106% for nitrate in spiked drinking water were obtained).