Mercury has been determined in Ayurvedic dietary supplements (Trifala, Trifala Guggulu, Turmeric, Mahasudarshan, Yograj, Shatawari, Hingwastika, Shatavari, and Shilajit) by inductively coupled plasma-mass spectrometry (ICP-MS) and direct mercury analysis using the Hydra-C direct mercury analyzer (Teledyne Leeman Labs Hudson, NH, USA). Similar results were obtained from the two methods, but the direct mercury analysis method was much faster and safer and required no microwave digestion (unlike ICP-MS). Levels of mercury ranged from 0.002 to 56
Ayurveda is a traditional form of medicine that originated on the Indian subcontinent during the Vedic period and is still widely used by many [
There are also metallic-herb preparations called bhasmas, which are used in the
Other dietary supplements have been analyzed by ICP-MS for As, Pb, Hg, and Cd [
Samples of Ayurvedic dietary supplements were purchased over the internet. Standard reference materials Ephedra 3240 and tomato leaves were from NIST and dogfish liver (DOLT3) was from the Canadian Research Council. Approximately half of each bottle of dietary supplements sample was placed in a blender and then blended to homogenous composite prior to the analysis. For products provided in tablet form approximately, half of each bottle was manually grounded into homogenous composite. Trace metals grade 30% H2O2, concentrated HCl, HNO3 and concentrated H2SO4 were purchased from GFS (Powell, OH) and used for the digestion. A 1000 µg/mL Hg standard in 2% HNO3, from ICP International (Santa Rosa, CA, USA), was used to spike the samples and measure spike recovery.
Microwave digestion of about 0.7 g of sample was done using Milestone Ultrawave microwave digestion system (Shelton, CT, USA) and quartz tubes. The microwave system contains a large pressurize reaction chamber in which all samples were digested simultaneously. The reaction chamber was prepressurized using N2 gas prior to start the run. Power was 1500 Watts, with a starting temperature of 120°C and pressure at 40 bar and then the temperature increased linearly to 230°C for 8 min and then held at 230°C for 8 min. The reaction chamber was cooled to 25°C. After cooling to 25°C, a final 0.5 mL of 30% H2O2, and 0.5 mL of HCl were added to each sample, followed by diluting to 100.0 mL with deionized water. Acids concentrations in sample digests were approximately 2% HNO3 and 0.5% HCl (HCl was used to stabilize Hg). ICP-MS analysis was done on an Agilent 7700x ICP-MS (Santa Clara, CA, USA). Spiking standards were prepared by adding Hg from a stock standard solution of 1000 µg/mL Hg in 2% HNO3, from ICP International (Santa Rosa, CA, USA) to a flask containing a solution of 5% nitric acid and 1.0% HCl to a final concentration of 500
Percent recoveries of Hg spikes by ICP-MS and Hydra C.
Item | Name | ICP-MS percent recovery | Hydra C percent recovery |
---|---|---|---|
Tu-S1 | Turmeric | 106% | 110% |
Shv-S1 | Shatawari | 112% | 112% |
Shil-S1 | Shilajita | 93% | 106% |
Isotopes of Hg for ICP-MS, used with an iridium internal standard.
Element | Analyte mass | Internal standard mass |
---|---|---|
Hg | 201 | 193 |
Hg | 202 | 193 |
For the determination of Hg, a Hydra-C mercury analyzer, model IIc was used (Teledyne Leeman Labs Hudson, NH, USA) without any sample digestion. Approximately 100 mg of each dietary supplement sample (60–85 mg National Institute of Standard and Technology (NIST) Standard Reference material (SRM) 3240 (
Standard operating conditions for Hydra-C direct mercury analyzer.
Parameter | Time (s) | Temp (°C) |
---|---|---|
Dry | 50 | 250 |
Decomposition | 200 | 600 |
Catalyst | 60 | 600 |
Amalgam | 30 | 600 |
Integration | 60 | N.A. |
Oxygen flow | 300 ml/min | N.A. |
Prior to sample analysis Hydra-C instrument was calibrated using NIST traceable standards. Calibration was completed using aqueous standards prepared in 1.0% HNO3. Instrument linearity was established across two separate ranges; a low range (0 ng to 30 ng) and high range (40 ng to 600 ng). The high calibration range has a correlation coefficient (
The two methods gave very similar results for the ten samples analyzed, as shown in Table
Comparison between Hydra C and ICP-MS results, measured in duplicate.
Item | Hydra-C ( |
ICP-MS ( |
---|---|---|
Trifala Guggulu | 5.109 | 4.345 |
Trifala | 0.188 | 0.182 |
Turmeric | 0.006 | 0.004 |
Mahasudarshan | 9.519 | 10.644 |
Yograj | 8.233 | 9.766 |
Shatawari | 0.013 | 0.011 |
Hingwastika | 38.959 | 56.503 |
Shatavari | 0.007 | 0.006 |
Triphala | 0.002 | 0.005 |
Shilajita | 0.760 | 0.686 |
Trifala and Triphala are two different samples of what may be the same dietary supplement.
As a test of accuracy, Hydra C method found the amounts of Hg in standard reference materials (Table
Analysis of standard reference materials (SRMs) by the Hydra C for Hg.
QC Standards | Certified Hg content |
% recovery |
---|---|---|
SRM 3240 ephedra | 0.0167 ± 0.0005 | 101 ± 10 |
SRM tomato leaves | 0.0340 ± 0.004 | 100 ± 2 |
SRM DOLT 3 dogfish liver | 3.37 ± 0.14 | 101 ± 3 |
Comparison and practical considerations for using Hydra C versus ICP-MS.
Hydra C | ICP-MS |
---|---|
No Sample digestion |
Need sample digestion |
No Hazardous chemical or waste | Hazardous chemical or waste |
All of the Hg in each sample is collected on the amalgam prior to analysis | Hg can be lost from aqueous samples during digestion |
About 5 minutes/sample | About 30 min/sample |
All the Hg gets to the detector, so sensitivity is good. | ICP-MS system must provide very high sensitivity to compensate for Hg low degree of ionization in the plasma |
Decrease the chance of contamination | Chance of contamination during the digestion process |
No carry over effect or loss of sample (no tubing required) | Significant carry over effect and loss of sample via tubing. |
This work should not be taken as reflecting FDA policy or regulations.