Detection of Inorganic Arsenic in Rice Using a Field-Deployable Method with Cola Extraction

Overview

Wehmeier et al. measured total arsenic (tAs) by ICP-MS and inorganic arsenic (iAs) by HPLC-ICP-MS in 30 rice and rice products purchased in Austria, as part of a method development study comparing a novel Cola-extraction field-deployable screening method against the reference HPLC-ICP-MS technique. This paper provides directly relevant food occurrence data for Austrian market rice. All As values are speciated: iAs was measured by HPLC-ICP-MS (Hamilton PRP-X100 anion exchange column, 40-mM ammonium carbonate mobile phase, Agilent 7700 ICP-MS). Total arsenic was measured by full acid digest + ICP-MS (Agilent 7900). CRM NIST 1568b recovery: tAs 299 ± 5 µg/kg (certified 285 ± 14); iAs 93 ± 1 µg/kg (certified 92 ± 10 µg/kg).

The iAs dataset across the 30 Austrian rice samples shows: range 60–249 µg/kg; mean 74% of total arsenic was iAs; DMA averaged 26% of total arsenic. Only one sample (an unpolished rice, R27) exceeded the applicable EU MCL for that rice type (250 µg/kg for unpolished/husked rice). If the infant rice MCL of 100 µg/kg were applied to all 30 samples, 22/30 would fail.

Key numbers

All concentrations in µg/kg (ppb) dry weight; measured by HPLC-ICP-MS (reference method) and ICP-MS (tAs). Full sample table in Table 2 of source.

Selected individual sample data (Table 2):

• Highest tAs: R2, 464 µg/kg (iAs 70 µg/kg, 16% — low iAs fraction despite high tAs)
• Highest iAs: R27, 249 ± 22 µg/kg iAs (tAs 262 µg/kg, 84% iAs — exceeded EU MCL for unpolished rice at 250 µg/kg)
• Lowest tAs: R15, 89 µg/kg (iAs 60 µg/kg, 79%)
• Infant rice products were among those with iAs >100 µg/kg (EU MCL for infant rice)

EU MCLs (2023 update): infant rice 100 µg iAs/kg, polished/parboiled rice 150 µg/kg, unpolished/husked rice 250 µg/kg, rice crackers 300 µg/kg.

Field method LOD: 39 µg iAs/kg (Cola extraction). Reference method LOD: iAs 8 µg/kg, DMA 9 µg/kg, MMA 0.4 µg/kg, tAs 41 µg/kg.

Methods (brief)

iAs speciation: HPLC-ICP-MS (Agilent HPLC 1260 Infinity + Agilent 7700 ICP-MS); Hamilton PRP-X100 anion exchange column; 40-mM ammonium carbonate mobile phase pH 9.2; 1% HNO3/1% H2O2 extraction at 99 °C for 1 h. EE 97%, chromatographic recovery 95%. tAs: full acid digest (sub-boiled HNO3, UltraClave) + ICP-MS (Agilent 7900, collision cell, He gas, m/z 75). Internal standards: Ge (m/z 74), In (m/z 115). CRM NIST 1568b recovery: tAs 105%, iAs within certified uncertainty.

Implications

Certification: Austrian market rice products (n=30): iAs range 60–249 µg/kg. Only 1/30 exceeded the applicable EU MCL; 22/30 would fail the strict 100 µg/kg infant rice MCL. This dataset confirms Austrian compliance with standard rice limits but highlights that most market rice is not safe for exclusive use as infant staple.

Courses: Illustrates the non-substitutability of iAs and tAs in compliance assessments: total arsenic (range 89–464 µg/kg) did not correlate well with iAs content (some high-tAs samples had only 16% iAs fraction). HPLC speciation is non-negotiable for regulatory and health assessment purposes.

App: Austrian market rice (n=30): iAs 60–249 µg/kg; mean iAs 74% of tAs. Infant rice products require the strictest standard (100 µg/kg iAs); most polished market rice falls in the 60–176 µg/kg range by HPLC-ICP-MS.

Wiki pages updated on ingest

• Arsenic
• Rice
• Infant Rice Cereal
• eu-iAs-rice-2023

Update history

The five most recent substantive edits to this page, classified major (evidence or structure moved), correction (a published value or statement was wrong and has been fixed), or minor (narrative rewritten without changing the underlying evidence). Each description is derived from what the edit did to this page; the linked commit is the authoritative record, routine regeneration passes are excluded, and 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.