Inorganic Arsenic In Rice Research Articles

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)

An alternative analytical method was developed for the quantification of inorganic arsenic (iAs) in rice by ICP OES. Iron nanoparticles modified with an organophosphorus compound were used as the solid phase for MSPE of iAs from the plant matrix. The MSPE procedure was performed using 4 mL of a buffer solution with pH 4.0, 20 mg of the nanomaterial, and a 15-min extraction time. The total As (tAs) by ICP OES was also quantified using the same MSPE procedure after solubilization of the samples by a block digester. The accuracy of tAs and iAs quantification was verified using CRM NIST 1568b (97 % and 101 % recovery, respectively). The precision (RSD < 15 %) and LOD and LOQ (1.08 and 3.70 µg kg−1, respectively) of the proposed method were satisfactory. The rice samples had tAs contents between 0.090 and 0.295 mg kg−1 and iAs mass fractions between 0.055 and 0.109 mg kg−1.

Novel covalent organic frameworks based electrospun composite nanofiber membranes as pipette-tip strong anion exchange sorbent for determination of inorganic arsenic in rice

Novel covalent organic frameworks (COFs) based PAN@TpBD(NH2)2 electrospun composite nanofiber membranes (ECNMs) were fabricated as strong anion exchange sorbent by implementing electrospinning technology. The finished sorbent was characterized, and key parameters of pipette-tip solid phase extraction (PTSPE) procedures were investigated. Inorganic arsenic (iAs) was successfully separated from rice under the optimal precondition conditions, and quantified by hydride generation-atomic fluorescence spectrometry (HG-AFS). This PTSPE-HG-AFS methodology achieved 0.015 μg L-1 detection limit, 4.67 % relative standard deviation, and 86.48～99.11 % recoveries. In this work, preparation and characterization of this novel COFs-based anion exchange sorbent, PAN@TpBD(NH2)2 ECNMs, is described and its suitability for PTSPE applications is demonstrated.

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

Herein, a colorimetric sensing system based on cerium(IV) coordination polymer nanoparticles (Ce(IV)-ATP-Tris CPNs) was proposed for As(V) detection. Ce(IV)-ATP-Tris CPNs show excellent oxidase-like activity, triggering 3,3′,5,5′-tetramethylbenzidine (TMB) chromogenic reaction. With addition of ascorbic acid 2-phosphate (AAP) and acid phosphatase (ACP), ACP can hydrolyze AAP to produce antioxidative ascorbic acid (AA), inhibiting TMB chromogenic reaction. After that, introduction of As(V) can inhibit ACP, recovering TMB chromogenic reaction. Therefore, sensitive and selective As(V) detection is achieved. Moreover, Ce(IV)-ATP-Tris CPNs were transformed into cellulose nanofiber (CNF) to form test strip (Ce(IV)-ATP-Tris CPNs/CNF). Inorganic arsenic in rice can be detected by test strip, color of that can be measured by smartphone-integrated colorimetric quantitative analysis platform. Given this, rapid and convenient strip test of inorganic arsenic in rice by using this platform was achieved. Hence, this platform possesses great application potential in the field of inorganic arsenic in rice, even food safety.

Determination and uncertainty analysis of inorganic arsenic in rice by UHPLC-ICPMS

The present study arose from the need of to determine inorganic arsenic (iAs) at low levels in rice. Ultra-high performance liquid chromatography coupled with inductively coupled plasma mass spectrometry (UHPLC-ICPMS) using Kinetic Energy Discrimination (KED) mode to eliminate spectral interferences was used for analysis of iAs. Sample preparation involves extraction of inorganic arsenic (sum of As3+ and As5+) with water by heating at 90 °C for 5 min in water bath. Separation is accomplished with a reversed-phase ion pack column using a gradient chromatographic method followed by ICPMS analysis within 5 min. The method was validated in accordance with Commission Regulation (EU) No 836/2011 and performance characteristics were verified. Acceptable values were obtained for specificity, repeatability (HorRatr &lt; 0.6), within-lab reproducibility (HorRatR &lt; 0.3) with recovery 80-90%, limit of quantification (0.02 mg/kg), fitness-for-purpose and trueness (using CRM); thus, the method can be considered for official control purposes.

Associations between inorganic arsenic in rice and groundwater arsenic in the Mekong Delta

There is growing concern regarding human dietary exposure to arsenic (As) via consumption of rice. The concentration and speciation of As in rice are highly variable, and models describing rice As speciation as a function of environmental covariates remain elusive. We conducted a survey of paddy rice and soil in the Mekong Delta with the objective of linking patterns in rice As content to soil chemical variables or hydrogeological parameters. The sum of As species (ΣAs) in husked rice averaged 243 μg/kg and the average inorganic As (iAs) content was 84%. There was no relationship found between rice As concentration or speciation and As levels in soil. However, mean As concentrations in groundwater near rice sampling locations were strongly correlated with grain ΣAs and iAs over a large part of the study region, despite the fact that groundwater is not commonly used for rice paddy irrigation in this region. We hypothesize that surficial sediments with high concentrations of soluble and plant-available As also serve as sources of arsenic to downgradient shallow aquifers, explaining the observed associations between rice and groundwater As. This study suggests that shallow groundwater As concentrations may serve as a useful indicator for locations at risk of elevated iAs concentrations in rice.

Assessing inorganic arsenic in rice and its health risk to consumers in Ho Chi Minh City, Vietnam

PurposeThe consumption of rice that contains high levels of inorganic arsenic may cause human health risk. This study aims to determine As species concentrations, particularly iAs, in raw rice in Ho Chi Minh (HCM) City and its health risks.Design/methodology/approachA total of 60 polished raw composite samples of rice were purchased from traditional markets and supermarkets in HCM City. All samples were analyzed by HPLC-ICPMS for As species determination.FindingsMean concentrations of inorganic arsenic in all samples, which were purchased from supermarket and traditional market, were 88.8 µg/kg and 80.6 µg/kg, respectively. Overall, inorganic arsenic level was 84.7 µg/kg and contributed the highest proportion of arsenic species in rice with 67.7%. The proportion profiles for arsenic species were: As (III) (60 %); dimethylarsinic acid (32.2 %); As (V) (7.7 %) and methylarsonic acid (0.1 %). Inorganic arsenic level in raw rice was below the recommendation of World Health Organization. Using the benchmark dose recommended by the Joint FAO/WHO Expert Committee on Food Additives (JECFA), all exposure doses were lower than BMDL05. However, as the doses ranged from 3.0 to 8.6 of Margin of Exposure (MOE), the health risk of iAs from rice consumption remains public health concern.Originality/valueThe study results report on the surveillance data of the presence of inorganic arsenic in raw rice products, which are available in the supermarkets and traditional markets, and its health risk to consumers in a metropolitan city in Vietnam.

Inorganic arsenic in rice and rice products in New Zealand and Australia

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.

Establishment of arsenic speciation analysis method and application 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.

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

A commercial arsenic field kit designed to measure inorganic arsenic (iAs) in water was modified into a field deployable method (FDM) to measure iAs in rice. While the method has been validated to give precise and accurate results in the laboratory, its on-site field performance has not been evaluated. This study was designed to test the method on-site in Malawi in order to evaluate its accuracy and precision in determination of iAs on-site by comparing with a validated reference method and giving original data on inorganic arsenic in Malawian rice and rice-based products. The method was validated by using the established laboratory-based HPLC-ICPMS. Statistical tests indicated there were no significant differences between on-site and laboratory iAs measurements determined using the FDM (p = 0.263, ά = 0.05) and between on-site measurements and measurements determined using HPLC-ICP-MS (p = 0.299, ά = 0.05). This method allows quick (within 1 h) and efficient screening of rice containing iAs concentrations on-site.

Inorganic arsenic in rice and rice-based diets: Health risk assessment

Total and inorganic arsenic (As) content in rice and rice-based diets (n = 59) obtained from supermarkets in South Australia were studied to investigate the contamination levels and whether consumption of these products pose potential health risks to young children and adults. Results show that of the 59 rice-based products, 31 (53%) exceeded the EU recommended value (100 μg/kg) of As for young children and 13 (22%) samples had higher than maximum level of 200 μg/kg recommended for adults. Arsenic content varies as rice crackers > baby rice > rice cakes > puffed rice > other rice-based snacks > ready-to-eat rice. Of the 6 categories of rice-based products, except ready-to-eat rice, all others exceeded the EU recommended value for young children. Even manufacture recommended servings deliver significant amounts (0.56–6.87 μg) of inorganic As. These amounts are within the range of BMDL01 values indicated by the European Food Safety Authority (EFSA), which means the risk cannot be avoided for young children and adults considering the levels of total and inorganic As in rice-based products.

Speciation of Arsenic in Rice by Ion Chromatography with Online Anion Suppression and Inductively Coupled Plasma Mass Spectrometry

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.

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

We developed a new fast and selective analytical method for the determination of inorganic arsenic (iAs) in rice by a gas chromatography – tandem mass spectrometry (GC-MS/MS) in combination with one step derivatization of inorganic arsenic (iAs) with British Anti-Lewsite (BAL). Two step derivatization of iAs with BAL has been previously performed for the GC-MS analysis. In this paper, the quantitative one step derivatization condition was successfully established. The GC-MS/MS was carried out with a short nonpolar capillary column (0.25 mm × 10 m) under the conditions of fast oven temperature ramp rate (4 °C/s) and high linear velocity (108.8 cm/s) of the carrier gas. The established GC-MS/MS method showed an excellent linearity (r2 > 0.999) in a tested range (0.2–100.0 μg L−1), ultra-low limit of detection (LOD, 0.08 pg), and high precision and accuracy. The GC-MS/MS technique showed far greater selectivity (22.5 fold higher signal to noise ratio in rice sample) on iAs than GC-MS method. The gas chromatographic running time was only 2.5 min with the iAs retention time of 1.98 min. The established method was successfully applied to quantify the iAs contents in polished rice. The mean iAs content in the Korean polished rice (n = 27) was 66.1 μg kg−1 with the range of 37.5–125.0 μg kg−1. This represents the first report on the GC-tandem mass spectrometry in combination with the one step derivatization with BAL for the iAs speciation in rice. This GC-MS/MS method would be a simple, useful and reliable measure for the iAs analysis in rice in the laboratories in which the expensive and element specific HPLC-ICP-MS is not available.

Speciation and monitoring of inorganic arsenic in rice by HPLC‐ICP/MS

Inorganic arsenic (As) species are more toxic than organic arsenic. Arsenite (AsIII) and arsenate (AsV) are the major compound in rice. We have monitored 50 samples of brown rice and white rice collected around Korea. Arsenic speciation in rice was analyzed for 4 different As species (Inorganic arsenic AsIII and AsV, DMA (dimethyl arsenic acid), MMA (monomethyl arsonic acid)) by high performance liquid chromatography coupled with inductively coupled plasma/mass spectrometry (HPLC‐ICP/MS) after a wet digestion‐sonication extraction. The total arsenic was measured by ICP‐MS after microwave‐assisted digestion. We used NIST 1568‐b white rice flour certified reference materials (CRM) in order to validate the method for determining the concentration of total As and Arsenic species. For the validation of method, several parameters have been performed and evaluated, namely: linearity, the limit of detection (LOD), the limited of quantification (LOQ), recovery·accuracy, precision. Total arsenic concentration in white rice samples varied from 0.076 to 0.135 mg/kg As (n=50) in white rice samples. In brown rice samples (n=50) have total As concentration ranging from 0.089 to 0.242 mg/kg. The average concentration of inorganic arsenic was 0.064±0.017 mg/kg in white rice samples and 0.119±0.029 mg/kg in brown rice samples. The percentage of inorganic As based on total As were 62.68±7.70% in white rice and 69.80±8.78% in brown rice.

Arsenic speciation in locally grown rice grains from Hunan Province, China: Spatial distribution and potential health risk

Arsenic contaminations have been evaluated in rice grains from Hunan Province, China. Forty-three locally grown rice samples were collected from 40 counties. Arsenic species including As(III), As(V), MMA and DMA were separated and determined by HPLC-ICP-MS method. The mean concentration of total arsenic in rice samples was 129.4±49.2μg/kg, lower than the Chinese maximum contaminant levels of inorganic arsenic in rice (200μg/kg). The dominant species detected in rice samples was As(III), following DMA, As(V) and MMA. The Pearson's correlation analysis indicated significant positive relationships between As(III) and total arsenic (r=0.939, p<0.01), and DMA and total arsenic (r=0.761, p<0.01). However, the percentage of As(III) decreased with the total arsenic concentration in rice (r=−0.515, p<0.01). Spatial distribution map of total arsenic concentration in rice samples from Hunan Province was obtained using kriging interpolation. High levels of total arsenic in rice grains were observed in south and east regions associated with mining activities and urbanization process. The cancer risk and hazard quotient were employed to estimate the potential human health risk. The results suggested great carcinogenic risk and high potential non-carcinogenic risk to people consuming local rice in Hunan Province.

A low-cost and environmentally-friendly potential procedure for inorganic-As remediation based on the use of fungi isolated from rice rhizosphere

Rice, a staple food for over half of the world’s population, represents a significant dietary source of inorganic arsenic. Thus, it is of great importance to reduce the levels of inorganic arsenic in rice with minimal cost and efficiency. Based on this, the present study focused on the isolation and identification of fungi present in soil rhizosphere to be used as a low-cost and environmentally-friendly procedure for inorganic arsenic remediation. Soil samples, from rice production areas, were evaluated in matter of toxic and essential elements (Pb, Cd, Ni, Mn, Se, Co, Cr, Ba, Rb, U, Cs, V, Cu, Fe, Mg, Zn) by inductively coupled mass spectrometry (ICP-MS). The isolated and identified filamentous fungi were Penicillium sp., Aspergillus sp., Trichoderma sp., Cladosporium sp., Rhizopus sp. and Westerdykella sp. Fungi were submitted to As3+ exposure in Czapeck growth media, and the biomass and broth of each fungus were analyzed by high performance liquid chromatography coupled to ICP-MS. The results have shown capacity of arsenic biotransformation and accumulation. Arsenic-tolerance test (0–50mgl−1As3+) has shown that the most arsenic-tolerant genera were Penicillium sp. and Aspergillus sp. Our data led us to believe that filamentous fungi may influence on arsenic biogeochemistry in rice paddy soils and further these microorganisms might be potentially used for bioremediation.

Detection of Inorganic Arsenic in Rice Using a Field Test Kit: A Screening Method.

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.

Speciation of inorganic arsenic species and total inorganic arsenic in rice using microwave-assisted dispersive liquid–liquid micro-extraction and electrothermal atomic absorption spectrometry

Human exposure to inorganic arsenic (iAs) via rice consumption is of increasing concern. In the present study, microwave-assisted dispersive liquid–liquid micro-extraction (MADLLME) and electrothermal atomic absorption spectrometry (ETAAS) were developed for the speciation of iAs in rice samples. After microwave-assisted digestion, the As(III) ion reacted with diethyldithiophosphoric acid (DDTP) to form an As–DDTP complex and was extracted at the same time. Some parameters affecting digestion, complex formation, and extraction were studied and optimised. Under the optimised conditions, a detection limit of 0.2 µg kg−1 with a correlation coefficient of 0.9901 were obtained with a calibration curve in the range of 0.5–200 µg kg−1. Total iAs was determined after reduction of As(V) to As(III) with sodium thiosulfate and potassium iodide, and As(V) was calculated by difference. The proposed extraction procedure was successfully applied for the determination of iAs ions in certified reference materials (NIST CRM 1568a and NMIJ CRM 7503a) and 10 rice samples produced in Iran and other Asian countries.

Presence of arsenic in Sri Lankan rice

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.

Determination of inorganic arsenic in rice by solid phase extraction and hydride generation atomic fluorescence spectrometry

Low-cost, simple methods are needed for accurate determination of iAs in food crops. Total arsenic (As) from rice was extracted and As5+ reduced to As3+. The combined As3+ was separated then quantified. This method appears suitable for general use due to its low cost.

Hydride generation ICP-MS as a simple method for determination of inorganic arsenic in rice for routine biomonitoring

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