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. 2025 Aug 25;47(10):411.
doi: 10.1007/s10653-025-02723-2.

Arsenic speciation using HPLC-ICP-MS in white and brown rice and health risk assessment

Raneesha Navaretnam  1 , Ahmad Zaharin Aris  1   2 , Muhammad Faizan A Shukor  3 , Mohd Nor Faiz Norrrahim  3 , Victor Feizal Knight  3 , Teen Teen Chin  4 , Noorain Mohd Isa  1   2 , Ley Juen Looi  5   6
Affiliations

Arsenic speciation using HPLC-ICP-MS in white and brown rice and health risk assessment

Raneesha Navaretnam et al. Environ Geochem Health. .

Abstract

Arsenic (As) contamination in rice poses significant health risks due to the toxicity of certain arsenicals. This study presents an improved, time-efficient method for quantifying arsenite (AsIII), arsenate (AsV), dimethylarsinic acid (DMA), and monomethylarsonic acid (MMA) in commercial white and brown rice using high-performance liquid chromatography coupled with inductively coupled plasma mass-spectrometry (HPLC-ICP-MS). The method incorporates chromatographic modifiers and ion-pairing agents in the mobile phase, reducing overall retention time to less than 4 minutes while enhancing peak separation. Method optimization, focusing on the solid-to-liquid ratio (g/L) and extraction time (minutes), was validated using the certified reference material (SRM 1568b Rice Flour), with measured concentrations showing good agreement with certified values. The MMA was excluded from the final analysis due to its low concentration in rice samples and minimal risk contribution. Arsenic species in rice followed the trend AsIII > DMA > AsV. No significant association was found between As levels and country of origin, but certain brown (MR 27, MR 29) and white (MR 10, MR 14) rice samples exceeded the European Commission's limit for inorganic As. Health risk assessments showed all rice samples had a target hazard quotient above 1, indicating potential non-carcinogenic risks. Additionally, estimated cancer risks exceeded the 10-3 (1 in 1000 lifetime risk) threshold under the revised cancer slope factor (CSF) value. This optimized method offers a reliable approach for detecting and quantifying As species in rice, aiding food safety monitoring and regulatory efforts.

Keywords: HPLC; ICP-MS; Inorganic arsenic; Rice; Risk assessment; Speciation analysis.

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Conflict of interest statement

Declarations. Competing interests: The authors declare no competing interests.

Figures

Fig. 1
Fig. 1
Distribution and speciation of arsenic species in rice from various rice-consuming countries. Base map courtesy of QGIS software version 3.28.5
Fig. 2
Fig. 2
Effect of pH on the retention time of different arsenic species in a mixed standard solution (10 µg/L); column C18 reversed-phase column (150 mm); flow rate: 1.2 mL/min
Fig. 3
Fig. 3
Impact of small variations in the pH on the separation of arsenic species: a pH 4.1, b pH 4.2, c pH 4.3, d pH 4.4, with a flow rate of 1.2 mL/min
Fig. 4
Fig. 4
Impact of flow rate adjustments (1.0 mL/min) on the separation of arsenic species at different pH levels: a pH 4.1 and b pH 4
Fig. 5
Fig. 5
Recovery of arsenic species (iAs, MMA, DMA) at different extraction durations and solid–liquid ratios. The solid–liquid ratios tested were 0.1 g SRM/10 mL HNO3 and 1 g SRM/10 mL HNO3, with extraction durations of 60, 90, and 120 min. The red dashed lines represent the acceptable recovery threshold range (70–120%). MMA recovery exceeded the acceptable range across all conditions
Fig. 6
Fig. 6
Concentration of arsenic species (AsIII, AsV and DMA) in white and brown rice (mg/kg) collected in this study
Fig. 7
Fig. 7
Inorganic arsenic concentration across all rice samples analysed in this study, compared with the maximum allowable limits for inorganic arsenic: 0.01 mg/kg for rice intended for infant food and snacks, 0.15 mg/kg for polished (white) rice, and 0.25 mg/kg for husked (brown) rice
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