Determination of Mercury in an Assortment of Dietary Supplements Using an Inexpensive Combustion Atomic Absorption Spectrometry Technique

Abstract

The concentrations of mercury in forty, commercially available dietary supplements, were determined using a new, inexpensive analysis technique. The method involves thermal decomposition, amalgamation, and detection of mercury by atomic absorption spectrometry with an analysis time of approximately six minutes per sample. The primary cost savings from this approach is that labor-intensive sample digestion is not required prior to analysis, further automating the analytical procedure. As a result, manufacturers and regulatory agencies concerned with monitoring lot-to-lot product quality may find this approach an attractive alternative to the more classical acid-decomposition, cold vapor atomic absorption methodology. Dietary supplement samples analyzed included astragalus, calcium, chromium picolinate, echinacea, ephedra, fish oil, ginger, ginkgo biloba, ginseng, goldenseal, guggul, senna, St John's wort, and yohimbe products. Quality control samples analyzed with the dietary supplements indicated a high level of method accuracy and precision. Ten replicate preparations of a standard reference material (NIST 1573a, tomato leaves) were analyzed, and the average mercury recovery was 109% (2.0% RSD). The method quantitation limit was 0.3 ng, which corresponded to 1.5 ng/g sample. The highest found mercury concentration (123 ng/g) was measured in a concentrated salmon oil sample. When taken as directed by an adult, this product would result in an approximate mercury ingestion of 7 µg per week.

Analysis of polychlorinated biphenyls (PCBs), heavy metals and omega‐3 fatty acids in commercially available Korean functional fish oil supplements

“…Levine et al . () attempted to use a combustion atomic absorption spectrometry technique to evaluate the mercury levels in an assortment of dietary supplements including fish oil products. A few other studies reported an analytical method to quantify the heavy metal elements and PCBs in fish oil supplement products (Schantz et al ., ; Gomara et al ., ; Rawn et al ., ; El‐Moselhy et al ., ).…”

“…Dalman et al (2006) determined the levels of heavy metal elements and trace elements in the fish of the south-eastern Aegean Sea in Turkey using atomic absorption spectrometry. Levine et al (2005) attempted to use a combustion atomic absorption spectrometry technique to evaluate the mercury levels in an assortment of dietary supplements including fish oil products. A few other studies reported an analytical method to quantify the heavy metal elements and PCBs in fish oil supplement products (Schantz et al, 1993;Gomara et al, 2005;Rawn et al, 2006;El-Moselhy et al, 2014).…”

Quality control of herbal medicines by using spectroscopic techniques and multivariate statistical analysis

“…All the chemicals (HCl (Qualigens, 36.5%), HNO 3 (Merck, 65%), and HClO 4 (Rankem, 73%)) used were of analytical grade. All the glassware was soaked with aqua regia (HCl:HNO 3 , 3:1) for 2 h (Levine et al, 2005). The completely dried sample (1 g) was digested in concentrated nitric acid and perchloric acid (3:1) until a clear solution with white fumes was obtained.…”

Method development for the determination of elements in Hypericum perforatum L. (St John's wort) herb and preparations using inductively coupled plasma–optical emission spectroscopy and microwave digestion

“…monitored 12 and our recent investigations found 15 elements in SJW preparations . Due to the lack of Certified Reference Materials (CRMs) available for SJW, a number of plant‐based CRMs have been reported for accuracy assessments including tomato leaves, peach leaves, spinach leaves, tea leaves, mixed Polish herbs, grass and tobacco …”