The Spectro-Electro Array: A Novel Platform for the Measurement of Secondary Metabolites in Botanicals, Supplements, and Beverages

Jun 01, 2012
Volume 30, Issue 6, pg 492–503

Antioxidant Capacity

There is considerable interest in the antioxidant capacity of botanical supplements, foods, and beverages with high levels of antioxidants purported to offer health benefits. There are a number of different approaches that vary in their ability to accurately measure the total antioxidant capacity of a given sample and these have been reviewed elsewhere (37,38). One approach, the oxygen radical absorbance capacity (ORAC) test, is routinely applied to foods. An advantage of the ORAC test is that it is relatively quick and easy to perform, however it can only provide data for the total antioxidant capacity of the sample rather than measuring the individual contribution of different antioxidants (39). The coulometric electrochemical array not only has the ability to identify and simultaneously quantify multiple antioxidants (and thus the contribution of individual compounds), but also the total antioxidant capacity of a sample can be calculated through the summation of the response of all analytes in the pattern. There is good correlation between ORAC and the coulometric electrode array (39,40).

Conclusions

Gradient HPLC with spectro-electro array detection can quantify a wide variety of important phytochemicals at trace levels in complex matrices such as botanical preparations, spices, wine, and fruit juice. To maintain data quality, sample preparation is kept as simple as possible and stabilizers are added to prevent auto-oxidation of analytes before injection. The sensitivity, wide dynamic range, and resolution of this combined approach is superior to traditional spectroscopic techniques.

Gradient elution and voltammetric resolution of similar compounds significantly extends the number of analytes capable of being measured simultaneously. The great utility of this method lies in the ability to separate and quantitate approximately 50 different phenolic and polyphenolic compounds in a wide variety of sample matrices. In addition, even unidentified compounds provide useful information when used in pattern recognition studies. These metabolite patterns are useful for evaluating product identity, purity, authenticity, and for differentiating among varietals, strains, and growing regions.

The spectro-electro array can be used to measure the total antioxidant capacity of a sample and to identify individual contributing antioxidants.


B.A. Bailey
B.A. Bailey is a product applications manager with Thermo Fisher Scientific in Chelmsford, Massachusetts.


D.H. Thomas
D.H. Thomas is a product and support scientist with Thermo Fisher Scientific.


I.N. Acworth
I.N. Acworth is director of customer and application support with Thermo Fisher Scientific.


P.A. Ullucci
P.A. Ullucci is with technical support at Thermo Fisher Scientific.


Michael Swartz
Michael Swartz "Innovations in HPLC" Editor Michael E. Swartz, PhD, is Principal Scientist in Analytical Development at Ariad Pharmaceuticals, Cambridge, Massachusetts, and a member of LCGC's editorial advisory board. Direct correspondence about this column to "Innovations in HPLC," at
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