Quantification of persistent organic pollutants in dietary supplements using stir bar sorptive extraction coupled with GC-MS/MS and isotope dilution mass spectrometry

ABSTRACT

In this work, we describe a method developed to quantify persistent organic pollutants (POPs) including polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs) in dietary supplement samples using stir-bar sorptive extraction (SBSE)-GC-MS/MS-isotope dilution mass spectrometry (IDMS). This method enables accurate, precise, and sensitive quantification of POPs in plant-extract based dietary supplement products commercially available in the United States. When compared with calibration curves, IDMS provided more accurate and precise measurements. The mean error of measurements using this method was 7.24% with a mean RSD of 8.26%. The application of GC-MS/MS enabled approximately two-order-of-magnitude lower limit of quantifications compared with GC-MS. 12 commercially available plant-extract based dietary supplement samples were analysed using this method. PAHs including naphthalene, acenaphthene, fluorene, phenanthrene, fluoranthene, pyrene, chrysene, and benzo[a]pyrene were detected in most of the products and had average concentrations over 1 ng/g. OCPs were detected less frequently than PAHs in these products, and none of the OCPs had mean concentrations over 1 ng/g. The mean toxin concentration of each product was calculated, and the highest value was 3.20 ng/g. These results were compared with existing guidelines and none of the analytes in the samples were found to be above the daily allowable limits.

KEYWORDS:

• Persistent organic pollutants
• dietary supplements
• stir-bar sorptive extraction
• GC-MS/MS
• isotope dilution mass spectrometry

Acknowledgments

The authors thank Agilent Technologies, GERSTEL, and Applied Isotope Technologies for providing the experimental materials, instrumentation, and other technical support. We appreciate the help and support from all members of the Duquesne University Kingston Research Group and specially thank Dr. Andrew Boggess, Dr. Scott Faber, Dr. Stephen Benchouk, and Mary Lynn Kingston for their insight and intellectual inputs.

Supplementary material

Supplemental data for this article can be accessed on the publisher’s website.