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. There exists no validated method for multi-residue analysis of pesticides in turmeric.

Objective: This study was undertaken 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 homogenized 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 graphitized 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 that of PSA, C18, and their combinations. The solvent exchange step with hexane was effective in removing co-extractives and minimizing matrix effects.

Conclusions: 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 multi-residue 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.