The method is described in Food Analytical Methods [2(4), 264–270(2009)], and forms part of a larger research project on Solid Phase Spectrophotometry and related applications. In the study, Professor Jiang and his team have developed a new solid phase spectrophotometry for the direct determination of brilliant blue in foods using β-cyclodextrin polymer.

“Conventional spectrophotometries are generally carried out in solutions, which show several disadvantages including time-consuming sample pretreatment process; especially the extraction using organic solvents is needed for some indissoluble analytes in aqueous solutions,” Jiang said. Regarding solid phase spectrophotometries, he believes there have been few reports on this project. “Although some ion-exchanges resins were also used as supports, ion-exchange resin phase spectrophotometries were only used in visible light regions because of the background adsorption in ultraviolet regions for the determination of the colored and exchanged analytes,” he added.

In order to expand the application areas of spectrophotometry, in the present study the team wanted to develop a solid phase spectrophotometry using a new kind of support, which is able to adapt to a wide range of ultraviolet- visible regions. “In this method, β-cyclodextrin polymer (β-CDP) was used as a solid phase extraction adsorbent to directly extract the food colourants such as brilliant blue from aqueous samples. β-CDP was synthesized by using epichlorohydrin and β-cyclodextrin, in which the basic structural units of β-CD are preserved and there is no absorption peak in ultraviolet-visible regions. A new solid phase spectrophotometry for the determination of trace amounts of brilliant blue in food has been developed using β-CDP as a support,” he continued.

For Jiang, the method has shown several important advantages including higher sensitivity than those of conventional spectrophotometries, low interference level, the use of conventional instrumentation and the simultaneousl preconcentration and colour development. “The proposed method seems to be a useful technique for the determination of trace amounts of constituents,” he added.

Food safety is still a very popular topic worldwide. Food additives are widely used and some are harmful to human health, such as azo food colourants, despite their low levels in foods. “The content of these colorants must be strictly controlled because the azo colourant can induce allergies and other diseases in sensitive people. In addition some azo food colourants such as brilliant blue have been banned in Austria, France, Germany, Italy, Spain, and Switzerland. Therefore, it is important to develop new methods for the determination of food additives, especially using some conventional instrumentation in the new methods. This study expanded the application of spectrophotometry in the determination of food additives,” he concluded.

For more information, contact the author, ztjiang@yahoo.com