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

1975 ◽  
Vol 58 (5) ◽  
pp. 915-919 ◽  
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.

Polarographic and spectrophotometric behaviour of some N-p-phenyl substituted benzamidines

1991 ◽  
Vol 56 (12) ◽  
pp. 2791-2799 ◽  
Author(s):  
Juan A. Squella ◽  
Luis J. Nuñez-Vergara ◽  
Hernan Rodríguez ◽  
Amelia Márquez ◽  
Jose M. Rodríguez-Mellado ◽  
...  
Keyword(s):  
Spectrophotometric Study ◽  
Absorption Bands ◽  
Electrochemical Parameters ◽  
Wide Ph Range ◽  
Group A ◽  
Substituent Constants ◽  
Ph Range ◽  
The Waves

Five N-p-phenyl substituted benzamidines were studied by DC and DP polarography in a wide pH range. Coulometric results show that the overall processes are four-electron reductions. Logarithmic analysis of the waves indicate that the process are irreversible. The influence of the pH on the polarographic parameters was also studied. A UV spectrophotometric study was performed in the pH range 2-13. In basic media some variations in the absorption bands were observed due to the dissociation of the amidine group. A determination of the pK values was made by deconvolution of the spectra. Correlations of both the electrochemical parameters and spectrophotometric pK values with the Hammett substituent constants were obtained.

scholarly journals Bio-template assisted synthesis of porous glutaraldehyde-polyethyleneimine particulate resin for selective copper ion binding and recovery

RSC Advances ◽  
2018 ◽  
Vol 8 (22) ◽  
pp. 12043-12052 ◽  
Author(s):  
Simarpreet Kaur ◽  
Ivan Kempson ◽  
Haolan Xu ◽  
Magnus Nydén ◽  
Mikael Larsson
Keyword(s):  
High Selectivity ◽  
High Capacity ◽  
Copper Ion ◽  
Precious Metals ◽  
Ion Binding ◽  
Ion Exchange Resins ◽  
Wide Ph Range ◽  
Ph Range ◽  
Exchange Resins ◽  
Template Assisted Synthesis

Porous ion-exchange resins with features of high selectivity, high capacity, fast adsorption kinetics and chemical stability over a wide pH range are attractive for extracting precious metals like copper and upcycling waste.

scholarly journals Novel Coprinopsis cinerea Polyesterase That Hydrolyzes Cutin and Suberin

2009 ◽  
Vol 75 (7) ◽  
pp. 2148-2157 ◽  
Author(s):  
Hanna Kontkanen ◽  
Ann Westerholm-Parvinen ◽  
Markku Saloheimo ◽  
Michael Bailey ◽  
Marjaana Rättö ◽  
...  
Keyword(s):  
Residual Activity ◽  
Fatty Acid Esters ◽  
Coprinopsis Cinerea ◽  
Outer Bark ◽  
Metal Affinity ◽  
Wide Ph Range ◽  
Ph Range ◽  
Laboratory Fermentor ◽  
Acid Esters

ABSTRACT Three cutinase gene-like genes from the basidiomycete Coprinopsis cinerea (Coprinus cinereus) found with a similarity search were cloned and expressed in Trichoderma reesei under the control of an inducible cbh1 promoter. The selected transformants of all three polyesterase constructs showed activity with p-nitrophenylbutyrate, used as a model substrate. The most promising transformant of the cutinase CC1G_09668.1 gene construct was cultivated in a laboratory fermentor, with a production yield of 1.4 g liter−l purified protein. The expressed cutinase (CcCUT1) was purified to homogeneity by immobilized metal affinity chromatography exploiting a C-terminal His tag. The N terminus of the enzyme was found to be blocked. The molecular mass of the purified enzyme was determined to be around 18.8 kDa by mass spectrometry. CcCUT1 had higher activity on shorter (C2 to C10) fatty acid esters of p-nitrophenol than on longer ones, and it also exhibited lipase activity. CcCUT1 had optimal activity between pH 7 and 8 but retained activity over a wide pH range. The enzyme retained 80% of its activity after 20 h of incubation at 50°C, but residual activity decreased sharply at 60°C. Microscopic analyses and determination of released hydrolysis products showed that the enzyme was able to depolymerize apple cutin and birch outer bark suberin.

scholarly journals A Novel Potentiometric Sensor for Determination of Nitrate ion based on N, N’- Ethylene-bis-(Salicylideneaminato) copper (II)

2021 ◽  
Vol 16 (3) ◽  
Author(s):  
Mohsin Ali ◽  
Jitendra Singh
Keyword(s):  
Selectivity Coefficient ◽  
Dioctyl Phthalate ◽  
Polymeric Films ◽  
Ion Concentration ◽  
Membrane Composition ◽  
Ion Sensors ◽  
Nitrate Ion ◽  
Ph Range ◽  
The One

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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