Multi-residue Analysis of Pesticides in Turmeric (Powder and Rhizome) Using Gas Chromatography Tandem Mass Spectrometry

Abstract

Background and objectives Turmeric is widely used as an ingredient of food and medicinal products. As there exists scarcely any validated method for multiresidue analysis of pesticides in turmeric, we aimed to develop a simple and robust method for the quantitative determination of multi-class pesticides in turmeric powder and rhizome by GC-MS/MS. Method Initially, the samples were soaked in water for 30 min and homogenised to a fine paste. A portion of this paste (2 g) was extracted with acetonitrile (2 mL) and partitioned with hexane (2 mL) after adding 5 mL of 20% NaCl. The cleanup step involved dispersive solid phase extraction with graphitised carbon black (GCB, 5 mg/mL). Its performance was evaluated against primary secondary amine (PSA) and C18 sorbents. The cleaned extract was evaporated to dryness and reconstituted in ethyl acetate before GC-MS/MS analysis. The method was validated for a mixture of 208 multi-class pesticides at 10 ng/g and higher levels (i.e. 20 and 50 ng/g). Results The findings, which demonstrated a satisfactory recovery and precision (RSDs <20%) for all compounds at 10 ng/g and higher spiking levels, are aligned with the analytical quality control criteria of SANTE/12682/2019 guidelines. The cleanup effect of GCB was much superior to PSA, C18 and their combination. The solvent exchange step with hexane was effective in removing co-extractives and minimising matrix effects. Conclusion This method complies with the regulatory requirements and is fit-for-purpose for pesticide residue monitoring in turmeric. Highlights The study reports a validated GC-MS/MS method for multiresidue analysis of pesticides in turmeric for the first time. The method provided a high throughput analysis of multi-class pesticides in turmeric rhizome and powder matrices with satisfactory selectivity, sensitivity, accuracy and precision.