Overview
Al-Dhabi measured nickel, zinc, mercury, platinum, magnesium, and manganese in 25 commercial Spirulina products sold for direct human consumption. The study sampled tablets and capsules from seven declared countries of origin, digested powdered product material, and quantified elements by ICP-MS. Values are reported on a dry-weight basis in mg/kg d.w.; mercury is reported only as mercury (Hg) with no methylmercury speciation, so this page records it as total mercury (tHg).
Key numbers
Sample frame: 25 Spirulina supplement products, including 16 tablet products and 9 capsule products. The paper lists product codes, manufacturers, and countries of origin; the Key numbers below aggregate to the Spirulina supplement category and do not reproduce brand/manufacturer-linked values.
Table 2 and the abstract report the following concentration ranges in mg/kg d.w.:
| Analyte | Source label | Range | Notes |
|---|---|---|---|
| Nickel | Ni | 0.211-4.672 | Highest-abundance toxic-metal analyte in the measured panel after zinc; no nickel species split reported. |
| Zinc | Zn | 0.533-6.225 | Highest concentration range in the measured panel. |
| Mercury | Hg | 0.002-0.028 | Reported only as Hg; recorded here as tHg, not MeHg. |
| Platinum | Pt | 0.001-0.012 | The results text also says Pt concentrations were below the method’s detection limit; Table 2 nevertheless prints numeric Pt values, so the printed range is preserved with this inconsistency noted. |
| Magnesium | Mg | 0.002-0.042 | Reported as a measured element, despite the unusually low range for a nutrient mineral in Spirulina. |
| Manganese | Mn | 0.005-2.248 | The discussion identifies the maximum as 2.248 mg/kg d.w.. |
The paper states that all mercury values were <0.03 mg/kg d.w.. It also reports that the most abundant measured metals in the Spirulina samples were zinc and nickel, while mercury and platinum were the least abundant measured analytes.
Table 3 reports two statistically significant positive correlations at the paper’s stated critical r = 0.725 threshold: Hg with nickel (Ni) (r = 0.751) and Mg with Hg (r = 0.733), with P < 0.005.
Methods (brief)
The study obtained 25 Spirulina products from specialist shops. Tablet samples were ground with a mortar and pestle; capsule shells were removed and the powders used directly. Triplicate 100 mg powder portions were digested in Teflon PFA vessels with 65% HNO3 using a CEM MDS-200 microwave system. Elemental determination used ICP-MS on a Perkin Elmer Elan-6000 with certified reference materials from Merck used to prepare standard solutions. The paper reports forward power 1400 W, nickel sample and skimmer cones of 1.0 mm and 0.75 mm, sample flow 1.0 ml/min, and survey scanning from 4-245 amu.
Implications
This source adds a small, original occurrence dataset for algae-based dietary supplements, specifically Spirulina tablets and capsules. It is most useful for the supplements-algae-seaweed-based and broad dietary-supplements product rows because it measures products marketed for direct human consumption rather than cultivation biomass or environmental algae. The study did not measure arsenic, cadmium, lead, chromium, or methylmercury; it should therefore not be used to fill those analyte distributions for Spirulina supplements.
Related evidence
- Ingredient class — algae/seaweed-based
- Dietary Supplements
- Oral solids: tablets/caplets
- Oral solids: capsules
- Nickel
- Zinc
- Mercury, Total
- Platinum
- Magnesium
- Manganese
Update history
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