Ataee et al. 2016 — Pb and Cd in Kermanshah-market cereals and pulses by MA-DLLME-SFO/GFAAS

This methodological-validation study reports total Pb and Cd in seven Iranian cereal and pulse commodities — rice, wheat, barley, peas, beans, corn, and lentil — purchased from three local markets in Kermanshah province (West Iran) and quantified by graphite-furnace atomic absorption spectrometry after microwave-assisted dry ashing and a dispersive liquid–liquid microextraction step based on solidification of a floating organic drop (MA-DLLME-SFO). Pb concentrations in every rice and wheat sample across all three markets exceeded the WHO maximum allowable level for cereals (0.2 mg/kg) cited by the authors, ranging from 202 to 320 µg/kg in rice and 202 to 267 µg/kg in wheat. Cd was elevated above the WHO 0.1 mg/kg ceiling only in Market 1 rice (108 µg/kg). Method validation against two Chinese reference cereals (NCS ZC 73,008 rice and 73,009 wheat) returned recoveries within ~3 % of certified values.

Key numbers

Method figures of merit (Table 3, p. 278):

Mean ± SD concentrations across the three Kermanshah markets, µg/kg dry weight, n=3 per market×commodity (Table 4, pp. 279–280):

Spike-recovery (Market-1 only, Table 4): for each commodity-metal, two spike levels were tested at concentrations of the same order as the native level. Recoveries across all 24 spike experiments fell within 90–108 %, supporting the method’s accuracy in the cereal/pulse matrix.

Certified-reference-material accuracy (§3.9, p. 280):

The authors compare their analytical figures of merit against five prior preconcentration-AAS/ICP-MS methods (Table 5, p. 281); LOD (0.05 µg/kg), RSD (4.7–5.3 %), and enhancement factor (115–122) place the proposed method in the most-sensitive band for solid-matrix cereal Pb/Cd quantitation among the compared studies.

Methods (brief)

Sample preparation. 1.0 g of finely milled, oven-dried cereal was weighed into a porcelain crucible, dry-ashed in a muffle furnace by stepwise temperature ramp to 500 °C over 2 h and held 10 h. The residue was dissolved in 8 mL of 1 M nitric acid + 30 % hydrogen peroxide (3:1), filtered (Whatman), and brought to 25 mL with deionised water; 10.0 mL of this sample solution then underwent the MA-DLLME-SFO step.

Extraction. 1.0 mL of methanol (disperser solvent) containing 40.0 µL of 1-undecanol (extraction solvent) and 15.0 µL of DDTP (diethyldithiophosphoric acid, chelating agent) was injected rapidly into the 10.0 mL sample solution to form a cloudy suspension. The mixture was centrifuged at 5000 rpm for 3 min; the floating 1-undecanol droplet was solidified on an ice bath (melting point 13 °C) and transferred to an autosampler cup. 20.0 µL of the melted extract was injected into the GFAAS.

Instrumentation. Analytik Jena novAA 400 atomic absorption spectrometer with deuterium background correction, transversely heated graphite tube atomiser, MPE 60 autosampler; pyrolytic-graphite-coated graphite tubes with integrated product identification number platform (Analytik Jena Part No. 407-A81.026). Microwave closed-system Multiwave 3000 (Anton Paar) for digestion runs; Metrohm 692 pHmeter; Hettich Zentrifugen EBA20 centrifuge. Pd(NO₃)₂ + Mg(NO₃)₂ chemical modifiers (1000 + 300 mg/L). Wavelengths 283.3 nm (Pb) and 228.8 nm (Cd); peak-height measurement. Argon (99.999 %, Air Products UK) as purge/protective gas at 500 mL/min, gas-stop during atomisation.

Speciation. Total Pb and total Cd only. No arsenic or mercury panel. No speciation step.

Calibration & QC. External calibration over 0.1–50 µg/kg from a 1000 mg/L stock (Sigma, St. Louis MO). LODs derived as 3σ/m from seven replicate blank measurements. Calibration r² 0.992 (Pb), 0.995 (Cd). Intra-day RSD 4.7 % (Pb) and 5.3 % (Cd) at 0.5 µg/kg; inter-day RSD 6.0 % (Pb) and 6.8 % (Cd). Two Chinese CRMs (NCS ZC 73,008 rice, 73,009 wheat from China National Analysis Center for Iron and Steel, Beijing) used to verify accuracy.

Optimisation results retained from the method-development section (pp. 274–277): pH 1–4 maximises chelate recovery (the acidic DDTP solution at pH 2.4 needed no adjustment); DDTP concentration ≥ 0.15 % v/v gives complete extraction; ionic strength up to 5 % NaCl had no effect; extraction time was effectively zero because complex formation was instantaneous in the cloudy phase; sample volume above 10 mL degraded recovery (incomplete methanol dispersion).

Sampling design. Three local markets in Kermanshah province, West Iran. Seven cereal/pulse commodities per market. Iran-produced grains only. Triplicate digestions per market×commodity (n = 3 per cell). Sampling year not stated; manuscript received 30 September 2015, accepted 29 January 2016.

Implications

This source contributes Iranian-market occurrence data for total Pb and total Cd in seven bulk-grain commodities, plus a validated MA-DLLME-SFO/GFAAS analytical pipeline for ultra-trace quantitation in cereal matrices. Its principal contributions to the wiki evidence pool:

• A consistent Pb signal in Kermanshah-market rice (228–320 µg/kg across three markets) and wheat (202–267 µg/kg) that exceeds the WHO 0.2 mg/kg ceiling for cereals cited by the authors. Both commodities are Iranian-produced; contamination pathway is not investigated in this paper.
• A Cd signal in Market-1 rice (108 µg/kg) above the WHO 0.1 mg/kg ceiling, with marked between-market variability (108 → 55.3 → 13.8 µg/kg across markets 1–3). The Cd-in-corn series likewise spans an order of magnitude across markets (8.6 → 33.7 → 96.4 µg/kg).
• Below-detection Pb and Cd results across all three lentil samples and across all pea Cd samples; bean Pb measurable in two of three markets and bean Cd below detection in all three.
• A method-validation reference point: LOD 0.05 µg/kg dry weight, intra-day RSD 4.7–5.3 %, enhancement factor 115–122, and within-uncertainty agreement with NCS ZC 73,008 and 73,009 certified reference materials. Useful as a comparator for downstream methodological comparisons within the bulk-grain Pb/Cd literature.

The single-province sampling footprint (three markets in Kermanshah) and small per-cell replication (n=3) make this a B-tier contributor on its own; it should pool with other Iranian and regional cereal-survey data rather than anchor any standalone characterisation. The paper does not isolate a contamination pathway (soil, irrigation water, fertiliser, post-harvest handling, packaging) for the rice and wheat Pb exceedances.

Wiki pages this source may touch

• lead
• cadmium
• rice
• wheat
• corn
• maize
• beans
• lentils
• legumes
• cereals
• rice-bulk-grain
• other-grain-products
• legumes-pulses-other

Verification notes

• Frontmatter discipline. All ingredient and product slugs verified against the 2026-05-18 taxonomy snapshot. Barley and peas are not yet in the ingredient taxonomy; the paper-measured commodities are captured in matrices: (barley-grain, peas) and in the prose, with cereals and legumes carrying the umbrella ingredient routing. Auto-stub creation for barley/peas, if/when freq-2 is crossed by other sources, is the routing-layer’s job, not this page’s.
• Cite-key choice. ataee2016-iran-cereals-pb-cd follows the descriptive-suffix convention (first author, year, region, commodity, analytes). DOI is the canonical identity; cite-key is a human-readable handle.
• Evidence tier B. Peer-reviewed in IJEAC; method validated against two CRMs with within-uncertainty agreement; spike recoveries 90–108 %. Sampling footprint is single-province (Kermanshah) with n=3 per market×commodity cell, which is the dominant reason for B rather than A.
• WHO reference values. The paper cites WHO maximum allowable levels of 0.2 mg/kg (Pb) and 0.1 mg/kg (Cd) for cereals (reference [6], Commission Regulation (EU) Off. J. Eur. Union L 364, 5 (2006) — actually the EU Commission Regulation, which the paper labels “WHO”; this is the original wording in the paper). The wiki page reports the comparison the authors made; it does not extend the comparison to other contemporaneous limits (EU 1881/2006 cereal Pb at 0.20 mg/kg matches the cited value; EU 1881/2006 cereal Cd at 0.10 mg/kg also matches). The mismatch between the paper’s “WHO” attribution and the actual EU regulation citation in reference [6] is documented here for accuracy.
• Brand firewall (Part 12). No brand-name attribution to contamination values — the paper identifies samples only by market number (1, 2, 3) and commodity. Methods-section vendor/material names retained per the 2026-05-17 vendor-name exception: Analytik Jena, novAA, MPE 60, Anton Paar Multiwave 3000, Metrohm, Hettich Zentrifugen EBA20, Sigma, Merck, Whatman, NCS ZC 73,008 / 73,009 CRMs from China National Analysis Center for Iron and Steel, Air Products UK.
• Wiki/HMTc firewall (Part 2). No threshold proposals, no consumer-audience advisories, no synthesis claims against other papers. The Implications section reports what this paper contributes; cross-paper synthesis is the Part 9 workflow’s job.
• Speciation. Total Pb and total Cd only. No As/Hg panel, no Pb or Cd speciation. The frontmatter metals: reflects this ([Pb, Cd]).
• Basis. Dry weight as analysed (1.0 g oven-dried at 50 °C for 2 h, then dry-ashed at 500 °C for 12 h). All Table 4 values are on the dry-as-sold basis of the bulk grain commodities. No conversion to as-consumed or wet-weight basis is needed for the values reported; if downstream synthesis requires a wet-basis conversion, the paper does not provide moisture content for each commodity and a literature value would be required.
• Sampling year. Not stated; manuscript received 30 September 2015 and accepted 29 January 2016, so sampling likely occurred in 2014–2015. Left null in frontmatter.
• Data integrity. All 42 commodity×market×metal cells transcribed from Table 4 (pp. 279–280) and verified against the original PDF. Spike-recovery section (Market 1 only) and CRM results (§3.9) likewise transcribed and verified. No paper-internal contradictions identified.

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.