Determination of Chromium Species in Dietary Supplements Using Speciated Isotope Dilution Mass Spectrometry with Mass Balance

Abstract

In order to determine the health impact of chromium in dietary supplements, the Cr(III) and Cr(VI) must be independently measured and verified with mass balance (sum of both species equaling independent measurements of total chromium), as both may be present in finished products. Because Cr(III) is stable in acidic conditions and Cr(VI) in alkaline conditions, interconversions between species may occur in complex matrices and during analytical extraction, increasing the difficulty of quantification. A study was conducted to determine Cr(VI) and Cr(III) in dietary supplements. EPA Method 3060A extraction protocol was performed to extract Cr(VI), and EPA Method 3052 was performed on the extracted residue to digest the remaining Cr(III). Speciated isotope dilution mass spectrometry (SIDMS), as described in the EPA Method 6800 (update V), was implemented with ion-exchange chromatography inductively coupled plasma mass spectrometry (IC-ICP-MS). Method 6800 uniquely enables tracking and correcting for the bidirectional chromium interspecies conversions that occur during extraction and sample handling prior to instrumental analysis. Mass balance results indicated that the off-the-shelf dietary supplements analyzed during this study contained hexavalent chromium ranging from <DL (detection limit) to 122.4 ± 13.0 μg/g, which corresponds to concentrations from below detection levels to up to 16% of the total chromium content. This type of variation in the final products raises public health issues and points to a need to use a robust method that can accurately and reliably make species measurements including correcting for species conversions.

Essential and toxic elements in commercial microalgal food supplements

“…The potential monitoring enforcement should therefore encompass not only microalgal-based formulations but all food supplements. Previous studies have shown that some food supplements may be contaminated with the hexavalent form of Cr (Martone et al 2013) which is recognized as a human carcinogen (Sun et al 2015). Thus, it remains important to screen microalgal products to exclude such contamination and, as shown in the present study, none of the Spirulina and Chlorella products contained detectable levels of the Cr (VI) form.…”

Monitoring of essential and toxic elements in multi-ingredient food supplements produced in European Union

“…None of analyzed products contained detectable levels of the Cr(VI) form known to act as a carcinogen (Sun et al 2015). This is a very important finding if one considers a previous disquieting report of Cr(VI) constituting up to a 16% share in the total Cr quota in some FS available on the U.S. market (Martone et al 2013).…”

Atomic spectrometry update: review of advances in the analysis of clinical and biological materials, foods and beverages

“…Despite the recognition of this problem, clay-based products are consumed by pregnant women and others in many parts of the world. In order to separately measure concentrations of Cr III and Cr VI avoiding any inter-species conversion, Martone et al 144 used the EPA method 3060A to extract Cr VI followed by EPA method 3052 to separate Cr III from the residue. Christopher et al 18 used ID-ICP-MS to determine the concentration of Cd in the SRM 3280 Multivitamin/Multielement Tablets.…”