The Quantitative Analysis of Curcuminoids in a Food Additive and Foods Evaluated using Rapid HPLC with Electrochemical, UV or Fluorescence Detection
Turmeric, the rhizomatous herbaceous perennial plant of the ginger family, in dried powdered form is used as a culinary additive to impart a distinctive yellow-orange color to Pakistani, Indian and Thai cuisines. Although turmeric has been used for many years in Ayurvedic medicine, its potential use in Western medicine has only recently been explored. Research to date suggests that turmeric, besides having an immunomodulatory role, is also of use in preventing oxidative stress that can lead to inflammation, cancer and arthritis. The natural products in turmeric that are purported to possess health benefits include a number of curcuminoids including curcumin (C), demethoxycurcumin (DMC) and bisdemethoxycurcumin (BDMC).
A rapid HPLC method using a Thermo Fisher Scientific Dionex UltiMate 3000 electrochemical detector for the simultaneous measurement of C, DMC and BDMC was developed. Curcuminoids in three food products, including turmeric power, curry powder and a pellet curry sauce, were quantitatively determined after simple ultrasonic extraction with methanol. Separation of curcuminoids was achieved in just 3 min using a Thermo Fisher Scientific Dionex PA2 column (2.2 µm particles, 2.1 × 50 mm). With electrochemical detector, the LOD (S/N = 3) was 2pg (on column) for C and DMC and 4pg for BDMC; intraday precision (n = 10) was < 10% for 10pg (on column) and < 4% for 20pg curcuminoids. A comparison of different detection technologies showed that ECD was more sensitive than UV detection, and was both more sensitive and had more uniform response than fluorescence detection.