A smartphone-integrated colorimetric quantitative analysis platform based on oxidase-like Ce(IV)-ATP-Tris CPNs/CNF test strip for detection of inorganic arsenic in rice

Rice is a staple food eaten by more than 50% of the world's population and is a daily dietary constituent in most South East Asian countries where 70% of the rice export comes from and where there is a high level of arsenic contamination in groundwater used for irrigation. Research shows that rice can take up and store inorganic arsenic during cultivation, and rice is considered to be one of the major routes of exposure to inorganic arsenic, a class I carcinogen for humans. Here, we report the use of a screening method based on the Gutzeit methodology to detect inorganic arsenic (iAs) in rice within 1 h. After optimization, 30 rice commodities from the United Kingdom market were tested with the field method and were compared to the reference method (high-performance liquid chromatography-inductively coupled plasma-mass spectrometry, HPLC-ICP-MS). In all but three rice samples, iAs compound can be determined. The results show no bias for iAs using the field method. Results obtained show quantification limits of about 50 μg kg(-1), a good reproducibility for a field method of ±12%, and only a few false positives and negatives (<10%) could only be recorded at the 2015 European Commission (EC) guideline for baby rice of 100 μg kg(-1), while none were recorded at the maximum level suggested by the World Health Organization (WHO) and implemented by the EC for polished and white rice of 200 μg kg(-1). The method is reliable, fast, and inexpensive; hence, it is suggested to be used as a screening method in the field for preselection of rice which violates legislative guidelines.

Does the determination of inorganic arsenic in rice depend on the method?

Magnetic solid phase extraction as a nonchromatographic method for the quantification of ultratrace inorganic arsenic in rice by inductively coupled plasma-optical emission spectrometry (ICP OES)

Comparison of on-site field measured inorganic arsenic in rice with laboratory measurements using a field deployable method: Method validation

One step derivatization with British Anti-Lewsite in combination with gas chromatography coupled to triple-quadrupole tandem mass spectrometry for the fast and selective analysis of inorganic arsenic in rice

At one point during the reign of King Cotton, farmers in the south central United States controlled boll weevils with arsenic-based pesticides, and residual arsenic still contaminates the soil. Today, rice paddies cover fields where cotton once grew, and a large market basket survey published in the 1 April 2007 issue of Environmental Science & Technology now shows that rice grown in this area contains, on average, 1.76 times more arsenic than rice grown in California. With rice consumption increasing steadily in the United States, high-rice diets may be of concern, says principal investigator Andrew Meharg, chair of biogeochemistry at the University of Aberdeen, United Kingdom. Arkansas produces about half and California about 20% of the total rice grown in the United States. The rest comes from Louisiana, Mississippi, Texas, Missouri, and Florida. The total U.S. rice crop for 2004 was 6.4 million metric tons, or 1.6% of total world production, according to the USDA. USDA data further show that U.S. rice tends to be milled and packaged close to where it is grown. About 60% of the rice grown in the United States is eaten here, and this figure has been increasing by about 2–3% a year. Rice is eaten directly or processed into breakfast cereal, rice cakes, package mixes, pet food, and beer. U.S. rice also is exported to South America, Asia, and Europe. Meharg’s team purchased 134 varieties of rice, including brown, white, organic, polished, unpolished, and instant, at grocery stores across Arkansas and California. Meharg traced where the rice varieties originated from information on the packages and by performing a principal component analysis of selenium, cobalt, copper, and other minerals in the grain. “This elemental profile directly relates rice to soil on which it is grown,” says Meharg. Total arsenic levels in the 107 south central rice samples averaged 0.30 μg/g, compared to an average of 0.17 μg/g in the 27 California samples. A white rice sample from Louisiana ranked highest in total arsenic (0.66 μg/g), and an organic brown rice from California ranked lowest (0.10 μg/g). Organic growing conditions, however, do not guarantee low arsenic levels, since any rice growing in arsenic-laden soil soaks up arsenic, says Meharg. U.S. rice consumption averages about 12 grams daily, but Asian Americans average more than 115 grams daily; Hispanic and black consumers also have higher-than-average rice intakes. The U.S. EPA, which classifies inorganic arsenic as a group A human carcinogen, sets a daily limit at 10 μg/L from drinking water (the most frequent route of exposure). There is no U.S. standard for arsenic in food. However, Meharg calculated that people who eat more than 115 grams of high-arsenic rice could reach or surpass the drinking water standard. “High-arsenic” in this instance is based on the Louisiana sample that scored highest in arsenic content, assuming that the arsenic content was 42% inorganic, as measured by Meharg in a study published in the 1 August 2005 issue of Environmental Science & Technology. Rice grown in Bangladesh, the world’s hot spot for arsenic poisoning, contains about 80% inorganic arsenic, and people there eat 450 grams daily. Rice is recommended as a substitute for wheat for people with celiac disease, a condition in which the wheat protein gluten damages the intestinal lining and impairs absorption. Celiac disease afflicts 1 in 133 Americans. Gluten-free diets also are promoted for children with autistic spectrum disorders, although no clear scientific evidence supports the use of such a diet. Estimates published in the November 2001 issue of Pediatrics put the prevalence of autistic spectrum disorders at 6.7 children per 1,000, with 15% of these children on gluten-free diets. The arsenic levels in U.S. rice “are possibly cause for concern,” says John Duxbury, a soil chemist at Cornell University. He completed a market basket analysis of rice purchased in upstate New York that, like Meharg’s, found high levels of arsenic in rice grown in the south central United States. But Duxbury points out that the findings are perhaps less straightforward than they may seem. In contrast to Meharg’s calculations, the U.S. rice sample with the highest arsenic in Duxbury’s unpublished analysis contained only 22% inorganic arsenic. Moreover, Duxbury’s greenhouse experiments show that farmers could significantly reduce rice arsenic levels by applying less water to the plants. Other researchers are designing rice plants that absorb less arsenic. “Until this all gets sorted out, consumers shouldn’t be overly concerned,” Duxbury says. Nevertheless, rice fanciers might note that both Duxbury and Meharg found basmati rice imported from India and Pakistan and jasmine rice from Thailand to contain the least arsenic.

ABSTRACTArsenic speciation in rice has received attention due to its impact on food safety and human health. In this study, a sensitive method was developed for the determination of inorganic arsenic in rice using online anion suppression with ion chromatography and inductively coupled plasma mass spectrometry. HCl of 0.01 mol/L was the optimal extracting agent, and 38 mmol/L sodium carbonate and 15 mmol/L sodium acetate were used as the mobile phase to separate dimethylarsinic acid (DMA), arsenite, monomethylarsonic acid (MMA), and arsenate. The results showed that there were no significant losses or transformations with the anion suppressor and an improvement in sensitivity. The limits of quantification were 0.1 µg/L for DMA, As(III) and MMA, and 0.2 µg/L for As(V). The procedure was used to determine inorganic arsenic in rice; As(III) and DMA were the primary forms present. The reproducibility from seven measurements showed that the relative standard deviation was less than 1.68%. The recoveries were from 99.76 to 110.42%. The present work offers a new approach for the determination of inorganic arsenic in rice.

Objective: A new ion exchange column technology was used to establish an efficient and sensitive method for the detection of inorganic arsenic. Methods: Based on the new As Specia Fast Column, the pretreatment methods, liquid phase separation and mass spectrometry determination conditions of inorganic arsenic in rice were optimized. Finally, arsenic compounds were separated by As Specia Fast Column and detected by liquid chromatography inductively coupled plasma mass spectrometry. The external standard method was used for quantitative analysis. The detection limit, precision and accuracy of the method were determined by measuring the content of arsenic compounds in rice samples and rice standard samples. At the same time, three Guangdong rice samples were selected as the experimental samples of this study, and 1 g of each sample was weighed and measured in parallel three times. The method was compared with the method of liquid chromatography-atomic fluorescence spectrometry (LC-AFS) and liquid chromatography-inductively coupled plasma mass spectrometry (LC-ICP-MS) in the national standard. Results: The inorganic arsenic in rice was extracted with 0.5% nitric acid solution at 65 ℃ for 15 h, and the pH was adjusted to alkaline. The mobile phase A (8 mmol/L HNO(3), 50 mmol/L NH(3)·H(2)O) and mobile phase B (40 mmol/L HNO(3), 80 mmol/L NH(3)·H(2)O) were used as the mobile phase gradient elution (93%) . Five arsenic compounds can reach baseline separation under the conditions of RF power of 1 500 W and atomization gas flow of 0.97 L/min. The detection limits ranged from 0.114 to 0.331 μg/L, and the inorganic arsenic content in rice samples ranged from 0.063 to 0.232 mg/kg. The results of determination of arsenic compounds in rice flour reference materials were all within the uncertainty range indicated by the standard. The recoveries were 86.7%~106.7%, and the precision was 1.9%-12.5%. Compared with national standards, the results of determination of arsenate in rice were relatively close (using this method, LC-AFS, LC-ICP-MS to detect the content of arsenate in rice samples 1 was 0.231, 0.226, 0.236 mg/kg, respectively). However, due to insufficient sensitivity, the national standard method is difficult to detect low levels of arsenic compounds (Arsenobetaine was not detected in rice sample 1). The method can detect the content of arsenobetaine in rice sample 1 was 0.023 mg/kg. Conclusion: The established method can meet the requirements of inorganic arsenic determination in rice, and it is more rapid and accurate than the current national standard. It can better monitor and evaluate the content of i-As in rice, and provide accurate data for comprehensively grasping and evaluating the safety of rice consumption of residents.

Arsenic and heavy metals are implicated in causation of CKDu among farmers in dry zone of Sri Lanka. Rice has been identified as a major source of arsenic in research carried out in other countries. We analyzed 120 samples of new improved varieties (NIVs) and 50 samples of traditional varieties (TV) of rice for total arsenic content. Rice cultivated in Sri Lanka is contaminated with arsenic. Agrochemical dependent NIVs contain considerable amount (20.6 -540.4 μg/Kg) of arsenic. There is no difference between the arsenic content in NIV rice samples from areas where there is high or low prevalence of CKDu. TVs that are cultivated without using agrochemicals contain significantly less arsenic (11.6 - 64.2 μg/Kg). However, it is evident that the TVs also contain toxic metals if they are grown with fertilizers and pesticides. A high proportion of arsenic in rice exists in the inorganic form. Sri Lanka is a nation with high per capita consumption of rice. Codex Alimentarius recommends the maximum allowable limit for inorganic arsenic in rice as 200 μg/kg. Assuming that 70% of the total arsenic content exists in the inorganic form, this corresponds to a level of about 286 μg/kg of total arsenic. As such, 11.6% of the samples of NIVs exceeded this maximum recommended level in polished rice. Inorganic arsenic is a non-threshold carcinogen. Research should be focused on developing rice varieties that do not retain arsenic within the rice grain.

ABSTRACTA total of 200 rice and rice products from New Zealand and Australia were purchased from retail outlets during 2017 for inorganic arsenic analysis by ICP-MS. The survey of foods placed a particular emphasis on products marketed specifically for infants and young. A total of 159 samples (80%) gave positive results for inorganic arsenic, with a mean concentration of 0.06 mg/kg and a range of <0.01–0.14 mg/kg. Two products marketed for infants and young children age-cohort had the highest concentrations of inorganic arsenic. Both exceeded the EU maximum level for rice destined for the production of food for infants and young children of 0.1 mg/kg. The mean concentration of inorganic arsenic for only raw rice samples was 0.07 mg/kg, with a range of <0.02–0.12 mg/kg. In general, the concentration of inorganic arsenic in rice and rice products from New Zealand and Australia was low compared to concentrations reported from comparable studies overseas.

High levels of inorganic arsenic in rice in areas where arsenic-contaminated water is used for irrigation and cooking

Geographical variation of arsenic distribution in paddy soil, rice and rice-based products: A meta-analytic approach and implications to human health

Using hydride generation for the determination of inorganic arsenic in rice gives the same result as HPLC.

Rice is a staple food and known to accumulate inorganic arsenic (iAs), which is a class 1 carcinogen to humans. Arsenic field-deployable method kits, designed for water testing, are able to screen iAs in rice, to assure food safety and quick decision-making without the need for laboratory analysis. For the arsenic extraction within the field method, nitric acid is used. To make the field method on-site safer, cost-effective and easier to handle, the method was adapted using a Cola in the extraction process. The adapted field-deployable method was tested by screening a total of 30 rice and rice products from the Austrian market. To verify the results obtained by the Cola extraction field-deployable method, the obtained iAs concentration was compared to HPLC-ICP-MS results. The Cola extraction field method obtained an LOD of 39 µg iAs kg−1 rice, and with an average reproducibility of 14% RSD, the method was capable of recording no false-negative but 7% false-positive values at the 2023 updated European Commission (EC) limits for rice. All, but one, screened rice samples were within the EU limits for iAs in rice and rice products.

Arsenic is present in rice grain mainly as inorganic arsenic. Little is known about the effect of cooking on inorganic arsenic content in rice and its bioavailability. This study evaluated total arsenic and inorganic arsenic in rice cooked with arsenic-contaminated water, the bioaccessibility of As(III) and As(V) after simulated gastrointestinal digestion, and the extent of arsenic retention and transport by Caco-2 cells used as a model of intestinal epithelia. After cooking, inorganic arsenic contents increase significantly. After simulated gastrointestinal digestion, the bioaccessibility of inorganic arsenic reached 63-99%; As(V) was the main species found. In Caco-2 cells, arsenic retention, transport, and total uptake (retention + transport) varied between 0.6 and 6.4, 3.3 and 11.4, and 3.9 and 17.8%, respectively. These results show that in arsenic endemic areas with subsistence rice diets, the contribution of inorganic arsenic from cooked rice should be considered in assessments of arsenic health risk.