Analysis method development and health risk assessment of pesticide and heavy metal residues in Dendrobium Candidum

Herbal medicines that are widely used worldwide are easily contaminated by pesticides and heavy metals, threatening human health. In this study, a modified QuEChERS pre-treatment method combined with HPLC/GC-MS/MS was established for the determination of 24 pesticide residues in Dendrobium candidum. The average recoveries of 24 pesticides in D. candidum were 76.9-110.0% with the relative standard deviation (RSD) of 0.28-11.40%, and their limits of detection (LOD) and limits of quantitation (LOQ) were 0.005-10 and 0.011-22 mu g kg(-1), respectively. The results showed that 83.33% of all samples had detected pesticide residues with the concentrations of 0.06-312.83 mu g kg(-1). Meanwhile, microwave digestion combined with ICP-MS was used to detect the residues of 8 heavy metals in D. candidum. The average recoveries of 8 heavy metals were 82.7-108.1% with an RSD of 1.4-8.0%, and their LOD and LOQ were 0.0001-0.05 mg kg(-1) and 0.0003-0.2 mg kg(-1), respectively. The results indicated that 8 heavy metals were all detected in all samples, and the highest concentration of Zn was 11.97 mg kg(-1). Furthermore, the health risk assessment showed that the risk of the detected pesticides and heavy metals in samples to humans, specifically to the general population including adults and children, was acceptable.