A Dip‐and‐Read Test Strip for the Determination of Nitrite in Food Samples for the Field Screening

Abstract

A new test strip method for field screening of nitrite in aqueous samples based on the diazo‐coupling reaction between the nitrite and the Griess reagents has been developed. The test strip has a circular sensing zone that contains two layers: the Griess reagents act as the sensing reagent and is immobilized in the bottom layer; the top layer is a cellulose acetate membrane that can be used as a dialysis membrane to remove the matrix from the sample, which can enhance the selectivity of this method. When the test strip was directly dipped into the samples, a color change of the test strip was observed, and the intensity of color that appears on the test strip is proportional to the concentration of nitrite in the range from 0.50 to 25 µg mL⁻¹ in food samples. Under the experimental conditions, as low as 0.20 µg mL⁻¹ nitrite can be observed; most of anionic and cationic species as well as other sample matrixes basically do not interfere with the nitrite measurement.

Keywords:

• Test strip method
• nitrite
• field screening
• food sample

Acknowledgments

The authors thank the Tianjin Natural Science Foundation (No: 043801511) and the Key Technologies R&D Programme (No. 2001BA804A54; 2001BA804A21) for their financial support.