Overview
da Rosa and colleagues developed a simple dilute-and-filter LC-ICP-MS method for arsenite, arsenate, DMA and MMA in rice milk and applied it to four retail rice milks, with total arsenic measured by ICP-MS after microwave digestion. Total arsenic ranged from 14.57 to 46.94 µg/L, and all four arsenic species were found across the products. The paper is mainly a methods paper, but its Table 4 results are direct measurements of a plant milk.
Key numbers
- Wholegrain (brown) rice milk: total arsenic 46.94 ± 1.96 µg/L; As(III) 12.48, As(V) 6.99, DMA 22.57, MMA 1.24 µg/L (Table 4).
- Polished-rice milk I: total arsenic 29.48 ± 1.23 µg/L; DMA 16.64 µg/L (Table 4).
- Polished-rice milk II: total arsenic 15.33 ± 1.10 µg/L; MMA below LOD (Table 4).
- Brown-rice milk with coconut: total arsenic 14.57 ± 0.96 µg/L; DMA and MMA below LOD (Table 4).
Methods (brief)
For speciation, samples were diluted 3-fold in 9.0 mmol/L ammonium phosphate mobile phase, filtered and separated on an anion-exchange column coupled to ICP-MS. Total arsenic was measured by ICP-MS after nitric acid microwave digestion. LOQs were 0.25 to 0.43 µg/L; spike recoveries 81-116%. Each product was analysed in triplicate. Results are per litre and are kept unconverted.
Evidence Fitness
Four products, each one unit analysed in triplicate, so the data show the range found rather than a market survey. No certified reference material was used. The abstract calls arsenate the main species, which Table 4 does not support, and the text’s claim that brown-rice milks carry more arsenic holds only for the wholegrain product. Inorganic arsenic is not printed as a separate total. Rice milk is a plant milk, so this is direct evidence for the plant-milk page.