Preparation and characterization of a suite of ephedra-containing standard reference materials.

The National Institute of Standards and Technology, the U.S. Food and Drug Administration, Center for Drug Evaluation and Research and Center for Food Safety and Applied Nutrition, and the National Institutes of Health, Office of Dietary Supplements, are collaborating to produce a series of Standard Reference Materials (SRMs) for dietary supplements. A suite of ephedra materials is the first in the series, and this paper describes the acquisition, preparation, and value assignment of these materials: SRMs 3240 Ephedra sinica Stapf Aerial Parts, 3241 E. sinica Stapf Native Extract, 3242 E. sinica Stapf Commercial Extract, 3243 Ephedra-Containing Solid Oral Dosage Form, and 3244 Ephedra-Containing Protein Powder. Values are assigned for ephedrine alkaloids and toxic elements in all 5 materials. Values are assigned for other analytes (e.g., caffeine, nutrient elements, proximates, etc.) in some of the materials, as appropriate. Materials in this suite of SRMs are intended for use as primary control materials when values are assigned to in-house (secondary) control materials and for validation of analytical methods for the measurement of alkaloids, toxic elements, and, in the case of SRM 3244, nutrients in similar materials.

A systematic approach to quantitation of ephedra alkaloids in natural health products.

A method for accurate determination of ephedrine (E) alkaloids in natural health products (NHP) is described. The NIST dietary supplement standard reference materials (SRMs) were selected for these studies. These SRMs comprise ground Ma Huang herb (Ephedra sinica Stapf.), a spray dried extract of the former, and commercial formulations derived from gel caps and a protein drink. The efficiency of sonication-assisted extraction and Soxhlet extraction was studied using both ammonium formate and potassium phosphate in 3% methanol as extraction media. The efficiency of SPE clean-up of the extract deteriorated rapidly when increasing amounts of sample matrix or analyte were processed, because of limited cartridge capacity. Quantitation by the method of additions was required to ensure the highest accuracy using both LC-UV and ES-LC-MS-MS techniques. Whereas the LC-UV method is more convenient and precise, the results are more questionable than ES-LC-MS-MS, because species-specific detection is not possible.

Separation and quantitation of the stereoisomers of ephedra alkaloids in natural health products using flow injection-electrospray ionization-high field asymmetric waveform ion mobility spectrometry-mass spectrometry.

A method is described for the determination of ephedrine (E) and pseudoephedrine (PE) and their metabolites norephedrine (NE), norpseudoephedrine (NPE), methylephedrine (ME), and methylpseudoephedrine (MPE) alkaloids in natural health products by flow injection-electrospray ionization-high field asymmetric waveform ion mobility spectrometry-mass spectrometry (FI-ESI-FAIMS-MS). The determination of the six alkaloids requires the separation of diastereomic pairs of E-PE, NE-NPE, and ME-MPE. FAIMS was able to resolve/separate these isomeric pairs based on their gas-phase ion mobility differences. The FAIMS-based separation and detection approach has been tested on over-the-counter diet pills. Following the extraction of the tablets, either by pressurized fluid extraction developed in-house or with sonication, the ephedra alkaloids were quantified using a modified isotope dilution approach. Detection limits for the alkaloids ranged from 0.1 to 3 ng/mL, and a linear range of at least 2 orders of magnitude was observed for the six analytes. The throughput of the current configuration of the FI-ESI-FAIMS-MS system is 2 min/sample, which is significantly higher than conventional chromatographic approaches. The developed FI-ESI-FAIMS-MS method has been compared with a conventional LC-UV analysis, and good agreement has been found for the major alkaloids.