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Novel oxidative coupling reactions of cisapride or metaclopramide with phenoxazines and their applications in the determination of nitrite at trace level in environmental samples.

Authors
  • Al-Okab, Riyad Ahmed
  • Syed, Akheel Ahmed
Type
Published Article
Journal
Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy
Publisher
Elsevier
Publication Date
Nov 01, 2007
Volume
68
Issue
3
Pages
739–746
Identifiers
PMID: 17306617
Source
Medline
License
Unknown

Abstract

Phenoxazine (PNZ), 2-chlorophenoxazine (CPN) and 2-trifluoromethylphenoxazine (TPN) were used as new class of spectrophotometric reagents for the determination of nanoamounts of nitrite in presence of cisapride (CSP) and metaclopramide (MCP) as new electrophilic coupling reagents. The methods were based on the oxidation of CSP or MCP by nitrite in hydrochloric acid medium and coupling with PNZ, CPN or TPN to yield red color derivatives which were stable for about 3h and having an absorbance maximum in the range 520-530 nm. Beer's law is obeyed for nitrite in the concentration range 0.08-0.80 and 0.13-1.60 microg ml(-1) for phenoxazine-cisapride and phenoxazine-metaclopramide, respectively. The optimum reaction conditions and other important analytical parameters were established to enhance the sensitivity of these methods. Interference due to various non-target ions was also investigated. The methods were applied to the analysis of nitrite in environmental samples. The performance of proposed methods were evaluated by Student's t-test and variance ratio F-test indicated the significance of proposed methods over the reference spectrophotometric method (Association of Official Analytical Communities (AOAC) method for the determination of nitrite in water samples).

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