Determination of Nitrites, Nitrates, and Their Mixtures Using Flow Injection Analysis with Spectrophotometric Detection | Semantic Scholar (2024)

FAQs

What is the spectrophotometric method for determination of nitrite? ›

The reaction between Nitrite and Griess Reagent produces the violet color solution. The solution starts with a measurement of the absorbance curve for determination of maximum absorbance wavelength. The solution is followed by a measurement of absorbance with 1 minute interval time for determination of operating time.

The sample is then placed in a spectrophotometer, which measures the absorbance of light at a specific wavelength (usually around 520-540 nm). By comparing the absorbance of the sample to a calibration curve, the concentration of nitrate in the sample can be determined.

SUMMARY OF METHOD

The nitrite (that was originally present plus reduced nitrate) is determined by diazotizing with sulfanilamide and coupling with N-(1-naphthyl)-ethylenediamine dihydrochloride to form a highly colored azo dye which is measured colorimetrically.

Nitrate ion gives a brown ring wiith FeSO4 and conc. Sulphuric acid. But with nitrite ion a black coloured solution is obtained.

Spectrophotometry is a method to measure how much a chemical substance absorbs light by measuring the intensity of light as a beam of light passes through sample solution. The basic principle is that each compound absorbs or transmits light over a certain range of wavelength.

In a 1.0L Standard Flask containing approximately 600mL Type-I-water, dissolve 1.805 g potassium nitrate. Ensure all KNO3 is dissolved, make up to the mark with Type-I-water, mix and store in a suitably labelled plastic container. A blank of 0.25 mL extractant (or H2O) with the normal reagents is normally sufficient.

Testing is the only way to know if nitrates or nitrites are in your drinking water. If human or animal waste contaminates a well, nitrites will be detected first but will quickly convert to nitrates, which is why tests are done for nitrates.

The Nitrite Assay Kit utilizes the Griess Reagent, a classic protocol for the estimation of nitrite. In the assay, nitrite is reduced to Nitrogen Oxide using Griess Reagent I. Then, Nitrogen Oxide reacts with Griess Reagent II, forming a stable product that can be detected by its absorbance at 540 nm (A540).

The Nitrate Broth tubes are inoculated and incubated and then the two reagents (sulfanilic acid and dimethyl-naphthylamine are added to the tubes. If nitrale (NO:) has been reduced to nitrile (NO: ) then the tube will turn red which may develup slowly (5 mm), this is evidence that nitrite (NO) is present.

Nitrates are relatively inert, which means they're stable and unlikely to change and cause harm. However, bacteria in the mouth or enzymes in the body can convert them into nitrites, and these may be harmful. In turn, nitrites can either turn into: nitric oxide, which is beneficial for the body.

What is the relationship between nitrate and nitrite? ›

Nitrites are known to hold one nitrogen atom along with two oxygen atoms, whereas nitrates are known to hold one nitrogen atom, bonded to three different oxygen atoms. A nitrite can become a nitrate by the process of oxidation and similarly, a nitrate can become a nitrite by the process of reduction.

The majority of total nitrate intake is converted to nitrite by bacteria in the saliva, stomach, and small intestine.

The most commonly used method for soil and soil extract analysis of nitrite is a modified Griess-Ilosvay colorimetric method using a continuous flow analyzer.

Both of them are inorganic compounds composed of oxygen and nitrogen. The difference in the shape, structure, and function depends on the number of oxygen atoms they bring out. Nitrates have one nitrogen and three oxygen atoms, where nitrites have one nitrogen and two oxygen atoms.

Through diazotization reaction a complex compound forms rendering the mixture brilliant pink in color. This can be measured using a spectrophotometer at 540 nm in terms of its absorbance. The absorbance is the function of the intensity of the colour which is the direct result of the nitrites present in the water.

A spectrophotometric method for the determination of ammonia in aqueous media was investigated. This newly developed method for the reaction of ammonia with ninhydrin found to be simple, accurate and precise. A deep red color product was formed in the presence of sodium hydroxide at wavelength of 508 nm.

Spectrophotometric methods involve addition of a known excess of bromate to urea in an acid medium, followed by the determination of residual bromine and chlorine reacting with methyl orange and measurement of absorbance at 505 nm. The absorbance increases linearly with urea concentration (r = 0.9998).

In Basic Protocol 1, absorbance measured at 280 nm (A280) is used to calculate protein concentration by comparison with a standard curve or published absorptivity values for that protein (a280). In the Alternate Protocol, absorbance measured at 205 nm (A205) is used to calculate the protein concentration.