Identification of zeinoxanthin in orange juices

Antonio J Meléndez-Martínez1, George Britton, Isabel M Vicario

  • 1Department of Nutrition and Food Science, Faculty of Pharmacy, University of Seville, Seville, Spain.

Related Concept Videos

Redox Titration: Overview01:21

Redox Titration: Overview

Redox titration is a chemical analysis technique used to determine the concentration of an unknown substance by measuring the electron transfer in a redox (reduction-oxidation) reaction. The process involves gradually adding a titrant with a known concentration of an oxidizing or reducing agent, to the analyte, the solution with an unknown concentration, until reaching the endpoint, which indicates the completion of the reaction between the two substances. Ensuring the analyte is in a single...
Aryldiazonium Salts to Azo Dyes: Diazo Coupling01:11

Aryldiazonium Salts to Azo Dyes: Diazo Coupling

The reaction of weakly electrophilic aryldiazonium (also called arenediazonium) salts with highly activated aromatic compounds leads to the formation of products with an —N=N— link, called an azo linkage. This reaction, presented in Figure 1, is known as diazo coupling and occurs without the loss of the nitrogen atoms of the aryldiazonium salt. Highly activated aromatic compounds such as phenols or arylamines favor the diazo coupling reaction. The coupling generally occurs at the para position.
Precipitation Titration: Endpoint Detection Methods01:19

Precipitation Titration: Endpoint Detection Methods

In argentometric precipitation titrations, endpoints can be detected visually by the Mohr, Volhard, and Fajans methods. In the Mohr method, adding a soluble chromate indicator gives an initial yellow color to the analyte solution. As the titrant is added, the first excess of silver ions forms a red silver chromate precipitate, marking the endpoint. The solution pH should be maintained at about 8 by adding solid CaCO3.
In the Volhard method, a standard excess of AgNO3 is first added to the...