Rapid and Sensitive Analytical Assessment of Curcuminoids and Common Turmeric Adulterants using Liquid Chromatography and Tandem Mass Spectrometry

Authors: RAGHAVENDHAR, KOTHA - UNIVERSITY OF MARYLAND; FAKIR, TAREQ - UNIVERSITY OF MARYLAND; Byrdwell, W Craig; Luthria, Devanand - Dave

Submitted to: ACS Food Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/11/2021
Publication Date: 12/3/2021
Citation: Raghavendhar, K.R., Fakir, T.S., Byrdwell, W.C., Luthria, D.L. 2021. Rapid and sensitive analytical assessment of curcuminoids and common turmeric adulterants using liquid chromatography and tandem mass spectrometry. ACS Food Science and Technology. 1(11):2174-2181. https://doi.org/10.1021/acsfoodscitech.1c00356.
DOI: https://doi.org/10.1021/acsfoodscitech.1c00356

Interpretive Summary: Consumer acceptance and the potential health benefits of natural products present in dietary supplements, functional foods, and nutraceuticals have gained significant attention globally over the past few decades. For instance, turmeric, a plant-derived curry spice that originated from India and currently being consumed worldwide, has been well recognized for its health benefits determined by multiple in vitro, in vivo, animal and human studies. These health benefits of turmeric are primarily attributed to the three important curcuminoids present, namely curcumin, demethoxycurcumin, and bisdemethoxycurcumin which are present between 3-5% range of the total turmeric powder. The current method allows quick separation of three bioactive curcumionds and three commonly found adulterants in a single chromatographic run. The current method allows to quantify low concentrations, even 0.002% of adulterants present in turmeric with 97.3-100.3% accuracy.

Technical Abstract: Turmeric has gained significant interest among the research community in recent decades because it contains bioactive curcuminoids (curcumin, demethoxycurcumin, and bisdemethoxycurcumin). This increased demand for turmeric has resulted in occasional adulteration, commonly with azo dyes and other chemicals, of which a number of them are known to have toxic effects on human health. In this study, we have developed and validated a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method using a tandem sector quadrupole mass spectrometer to detect and quantify three curcuminoids and three of the most common food adulterants, particularly in turmeric, namely, metanil yellow, Sudan I and Sudan red using a single method. The method was validated for linearity, precision, accuracy. The limit of quantification (LOQ) and the limit of detection (LOD) were determined as 1-2 ng/mL and 0.1-0.2 ng/mL, respectively, for all six analytes (three bioactive curcuminoids and three adulterants). The method is precise and accurate, with intra-day and inter-day accuracies ranging from 86.4-108.1% and 86.0- 107.7%, respectively, and intra-day and inter-day coefficients of variation (CV) ranging from 0.9-5.2% and 1.6-5.6%, respectively. A simple extraction procedure, easy sample preparation, high sensitivity, and rapid analysis make this method suitable for routine analyses. The validated method was applied to quantify curcuminoids in six commercial turmeric supplements. To demonstrate the practical applicability of the validated method, 0.002-1% of adulterants were spiked in a commercial dietary turmeric supplement and their concentrations were quantified. The current method can detect adulterants as low as 0.002% in turmeric with 97.3-100.3% accuracy.