Rapid and Sensitive Analytical Assessment of Curcuminoids and Three Common Turmeric Adulterants in a Single Run Using Liquid Chromatography and Tandem Mass Spectrometry

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 simultaneously detect and quantify three curcuminoids (curcumin, demethoxycurcumin, and bisdemethoxycurcumin) and three of the most common food adulterants, particularly in turmeric, namely, metanil yellow, Sudan I, and Sudan red G using a single 11 min method. The method was validated for linearity, precision, and accuracy. The limit of quantification (LOQ) and the limit of detection (LOD) were determined as 1-2 and 0.1-0.2 ng/mL, respectively, for all six analytes. The method is accurate and precise, with intraday and interday accuracies ranging from 86.4 to 108.1 and from 86.0 to 107.7%, respectively, and intraday and interday coefficients of variation (CVs) ranging from 0.9 to 5.2 and 1.6 to 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. The amounts of curcuminoids varied significantly (similar to 30-fold) among the six supplements investigated in the present study. To demonstrate the practical applicability of the validated method, a commercial dietary turmeric supplement was spiked with 0.002-1% of adulterants, and their concentrations were accurately quantified. This method provides a rapid quantification of the three curcuminoids and three common adulterants simultaneously in a single run.