The alkalimetric determination of nitrate ion by means of a copper-catalysed reduction

Ionophore N, N’–Ethylene-bis-(Salicylideneaminato) copper (II) has been synthesized and characterized by IR and 1H NMR spectroscopy. Poly (vinyl chloride) based polymeric films of this ionophore along with cation discriminator (CTAB) and different plasticizers (dibutyl phthalate, dioctyl phthalate, 1-chloronapthalene and tri-n-butyl phosphate) were prepared and investigated as Nitrate ion sensors. Among all the different sensors fabricated, the one with membrane composition as I (7 mg): PVC (31 mg): DBP (60 mg): CTAB (2 mg) exhibited best characteristics. This sensor functions admirably over a wide concentration range 1.0×10−6–1.0×10−2 M with Nernstian compliance (59.8 mV per decade of concentration) between pH range 2.5–9.2 with a rapid response time of 13s. The sensor showed a lower detection limit 1.58×10-6 M. The selectivity coefficient values as determined by the fixed interfering method (FIM) show that the Nitrate ion has excellent selectivity over several anions. The sensor shows satisfactory time span of 2 months with great reproducibility while used continuously daily for 4 hrs. The sensor has been successfully utilized in the determination of nitrate ion concentration in different water samples.

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Nitrate Determination in Baby Food, Using the Nitrate Ion Selective Electrode

Journal of AOAC INTERNATIONAL ◽

10.1093/jaoac/58.5.915 ◽

1975 ◽

Vol 58 (5) ◽

pp. 915-919 ◽

Cited By ~ 3

Author(s):

Sandra L Pfeiffer ◽

Jean Smith

Keyword(s):

Ionic Composition ◽

Nitrate Content ◽

Nitrate Ion ◽

Cation Exchange Resins ◽

Wide Ph Range ◽

Nitrate Determination ◽

Comparative Results ◽

Ph Range ◽

Exchange Resins

Abstract The nitrate electrode has been utilized in the determination of nitrate content in food products. The AOAC xylenol method was employed for comparative results. A reasonable correlation (r = 0.91) was found between the 2 methods in the analysis of 49 samples containing 30–350 ppm nitrate. At the average nitrate content (100 ppm) of these foods, the standard error was 4.3 ppm. The electrode responds directly to the ionic activity of the nitrate ion. It has a linear concentration range of 1–6000 ppm nitrate and can be used over a wide pH range. The electrode does respond to some extent to anions other than nitrate, and some interferences do occur. These interferences are easily controlled by the use of cation exchange resins. The Corning known addition (spiking) method is used on all samples to insure correct electrode response in solutions containing variable background ionic composition. The electrode has the advantage of simplicity, speed, reproducibility, and accuracy. Work time saved using the electrode as opposed to the xylenol method is about 7 hr for the analysis of 20 samples. Error, and the need for repeating analysis, is much less frequent.

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