Multiresidue screening of organochlorine pesticides in herbal products marketed in Singapore

In Singapore, there has been a significant and growing interest in herbal preparations/or health supplements from natural products. However, no quality control procedures in terms of pesticide contamination are required for the import of herbal materials at this moment. Therefore, a pesticide screening study of the local marketed herbal products is of particular interest. In the present study, Solid-Phase Extraction (SPE) combined with Gas Chromatography Mass Spectrometry (GC/MS) in selected-ion monitoring (SIM) mode for the simultaneous analysis of organochlorine pesticide residues (OCPs) in herbs or their formulations was developed. Nine selected herbal preparations in the different forms, such as raw material, powder, capsule, pill and tablet were purchased from the local market and screened for OCPs. Although OCPs were detected in most of the samples, their concentrations were found well below the Maximum Residue Level (MRL) set in the European Pharmacopoeia (2008). α-BHC, β-BHC, γ-BHC, γ-chlordane, p,p'-DDE and hexachlorobenzene were the most frequently detected contaminants in these samples. These widespread pesticide contaminations may pose potential health risks to consumers and significantly affect the export of herbal products to new markets, thus must be carefully monitored.