Olafisoye et al. 2020 — Metallic elements in Nigerian virgin palm oil

Olafisoye and colleagues measured synthetic antioxidants and twelve metallic elements in virgin palm oil sampled from fifteen plantation locations in southern Nigeria. The antioxidant screen found no detectable BHA, BHT, EEMC, or propyl gallate, while ICP-OES detected Al, Co, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Se, Sn, and Zn in the oil matrix. Lead, cadmium, and tin are the most relevant HMI signals: Pb ranged from 0.006 to 0.847 in the authors’ table units, Cd from 0.127 to 0.762, and Sn from 0.090 to 161.576, with the paper warning that most samples exceeded cited WHO vegetable-oil limits for several metals.

Key numbers

• Sample set: 15 virgin palm oil samples from Abak, Acharu, Agbarho, Ago-Emokpae, Apoje, Badagry, Benin City, Igede-Ekiti, Ikire, Iresaapa, Nsukka, Okitipupa, Onishere, Ubiaja, and Umuabi plantations or sampling areas.
• Metal scope: Al, Co, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Se, Sn, and Zn by ICP-OES after oil-water micro-emulsion preparation.
• Pb in oil, Table 3b: 0.006 ± 0.001 at Ubiaja to 0.847 ± 0.001 at Onishere. The paper states a WHO vegetable-oil limit of 0.01 for Pb and says most samples exceeded that limit, with Ubiaja as the exception.
• Cd in oil, Table 3a: 0.127 ± 0.001 at Abak and Badagry to 0.762 ± 0.002 at Igede-Ekiti. The discussion states all sampled plantations exceeded the cited WHO vegetable-oil limit of 0.005 for Cd.
• Sn in oil, Table 3b: 0.090 ± 0.004 at Agbarho to 161.576 ± 3.907 at Benin City. The abstract identifies tin as the highest-concentration element in Benin City plantation oil.
• Ni in oil, Table 3b: 0.068 ± 0.001 at Abak to 0.786 ± 0.001 at Apoje.
• Other reported ranges in oil, Tables 3a-3b: Al 0.018-0.833; Co 0.091-0.887; Cr 0.011-0.998; Cu 0.022-0.446; Fe 0.033-0.673; Mn 0.023-0.672; Se 0.011-0.926; Zn 0.053-1.621.
• Synthetic antioxidant validation: LODs were 0.041 mg/L for BHA, 0.057 mg/L for BHT, 0.006 mg/L for EEMC, and 0.003 mg/L for propyl gallate; none of these antioxidants was detected in the sampled oils.

Methods (brief)

For metals, the authors weighed 0.5 g oil into polypropylene tubes, added hydrochloric acid and propan-2-ol to a 10 mL final volume, shook the mixture for 30 minutes, refrigerated the micro-emulsion, and analyzed elements by radial-view ICP-OES. For antioxidants, they extracted 0.5 g oil with acetonitrile:hexane and analyzed BHA, BHT, EEMC, and propyl gallate by RP-HPLC with UV/Vis detection at 280 nm. The source reports location-specific oil values with mean ± error terms and states that the real samples were analyzed in triplicate.

Implications

Certification: The paper is direct occurrence evidence for virgin palm oil and broader edible cooking-oil rows, especially for Pb, Cd, Ni, and Sn. Because the tables label oil values in mg/L while the abstract describes a mg/kg range, HMTc pooling should preserve the source unit until a basis conversion is explicitly adjudicated.

Courses: The source is a useful example of plantation-location variability and of why edible oils can carry metals from environmental contamination, processing, or local agricultural conditions.

App: Palm oil can be flagged as having direct literature evidence for Pb, Cd, Ni, and Sn occurrence, with Nigeria-specific geographic context rather than a global palm-oil estimate.

Microbiome: No direct microbiome endpoint.

Wiki pages this source may touch

• palm-oil
• cooking-oils-other
• lead
• cadmium
• nickel
• tin

Verification notes

• The paper’s abstract says metallic-element concentrations ranged from 0.006 mg/kg to 161.576 mg/kg, but Tables 3a, 3b, and 4a-4c label the oil concentration columns as mg/L. This source page preserves the table values and flags the unit discrepancy rather than converting between volume and mass basis.
• The antioxidant LODs are also internally inconsistent: Table 2 reports EEMC and propyl gallate LODs as 0.006 and 0.003 mg/L, while the abstract reports 0.06 and 0.03 mg/L. The Key numbers section uses Table 2 because it is the method-validation table, but the discrepancy should remain visible for audit.
• The table text contains minor formatting defects from the PDF extraction, including “0239±0.001” for Agbarho Co, “0.020±±0.003” for Ikire Pb, and “0006±0.001” for Ubiaja Pb in Table 4b; values were read against Tables 3a-3b where possible.
• Matrix labels virgin-palm-oil, edible-oil, and vegetable-oil are source-specific routing descriptors for this source page; the ingredient and product routing slugs are [[ingredients/palm-oil]] and [[products/cooking-oils-other]].
• The source is not brand-specific and does not identify consumer brands; it reports plantation/location-level samples.

Page history

The five most recent substantive edits to this page. The full version history lives in git; when DOI minting comes online (see schema docs), each entry below will also link to a version-pinned DataCite DOI.