Combination of isotope dilution with liquid chromatography-inductively coupled plasma mass spectrometry for the simultaneous monitoring and evaluation of cadmium and inorganic arsenic in polished rice

A new monitoring and evaluation technique for cadmium (Cd) and inorganic arsenic (i-As) in rice was developed, where the isotope dilution (ID) method was applied in combination with high performance liquid chromatography-inductively coupled plasma mass spectrometry (LC-ICP-MS), following heat-assisted extraction. Cadmium and i-As in a rice sample were extracted using the HNO3-H2O2 extractant, and an appropriate amount of enriched 111Cd was spiked into it. Cadmium and As species were measured simultaneously by LC-ICP-MS. The cadmium concentration was calculated from the isotope dilution analysis, and i-As was determined by the comparison (1 point calibration) method using additional 111Cd as an internal standard. The proposed method provides accurate and precise determination of Cd based on the isotope dilution analysis. Moreover, it can be applied to a rapid screening test to find contaminated rice samples, by means of monitoring the intensity ratios of natural 111Cd and i-As to the additional 111Cd. The developed technique was applied to analyzing multiple rice reference materials, and the measurement results of Cd and i-As agreed with the certified values within the uncertainty range. It is noted that the grain size of rice samples does not affect the extraction data, when the rice sample is crushed into powder less than 850 μm. The proposed method was very useful for the monitoring and evaluation of Cd and i-As in rice as a precise analytical method as well as a screening method.

ICP-OES analysis of total As and Cd in Columbian Oryza sativa L. rice

Arsenic (As) and cadmium (Cd) are considered toxic elements, even at trace levels. Their accurate quantification in crops can be complex at low levels and due to interference with other elements. The aim of this work was to develop and validate an analytical method for As and Cd quantification in rice stem and grains from the production systems "Irrigated Rice Ecosystems" (IRE) and "Rainfed Rice Ecosystems" (RRE) in Colombia. Mineralisation was carried out by acid digestion using an open system with a heating plate. Metal detection was performed by inductively coupled plasma optical emission spectrometry (ICP-OES). Method adjustment, calibration, and validation were performed in accordance with AOAC standards, considering sensitivity, precision, accuracy, and selectivity parameters. The obtained method was applied to quantify levels in 259 rice stem and 443 grain samples from IRE and RRE.

Effects of CuO nanoparticles in composted sewage sludge on rice-soil systems and their potential human health risks

The release of metal-based nanoparticles (MNPs) into sewage systems is worrisome due to their potential impact on crop-soil systems that are amended with sewage sludge. This study aimed to investigate the effects of copper oxide nanoparticles (CuO NPs) in composted sewage sludge (CSS) on rice-soil systems and to assess the health risks associated with consuming CuO NP-contaminated rice produced by CSS amendment. CSS was treated with three doses of CuO NPs, resulting in Cu levels below the sludge limits (1500 mg Cu kg-1) for reuse as a soil amendment. Results showed that CuO NPs in CSS at environmentally acceptable levels had no negative effect on rice growth and yield. In fact, they enhanced biomass production, tillering capacity, and soil fertility by increasing N and K levels in the soil. In addition, CuO NPs in CSS (450-1450 mg Cu kg-1) promoted the accumulation of macro- and micro-minerals in rice grains, thereby improving the nutritional value of rice. However, Cu contamination in CSS led to elevated levels of toxic metals, especially As, in rice grains, posing potential health risks to both adults and children. In the presence of higher CuO NPs contamination in CSS, the hazard quotient of As exceeded one, indicating an increased risks of toxic metal exposure via rice consumption. This study raises concerns about potential long-term threats to human health posed by MNPs contamination in CSS and highlights the need to reevaluate the permissible limits of hazardous elements in sludge to ensure its safe reuse in agriculture.

Genotoxicity and mutagenicity in blood and drinking water induced by arsenic in an impacted gold mining region in Colombia

Arsenic (As) is one of the most dangerous substances that can affect human health and long-term exposure to As in drinking water can even cause cancer. The objective of this study was to investigate the concentrations of total As in the blood of inhabitants of a Colombian region impacted by gold mining and to evaluate its genotoxic effect through DNA damage by means of the comet assay. Additionally, the concentration of As in the water consumed by the population as well as the mutagenic activity of drinking water (n = 34) in individuals were determined by hydride generator atomic absorption spectrometry and the Ames test, respectively. In the monitoring, the study population was made up of a group of 112 people, including inhabitants of four municipalities: Guaranda, Sucre, Majagual, and San Marcos from the Mojana region as the exposed group, and Montería as a control group. The results showed DNA damage related to the presence of As in blood (p < 0.05) in the exposed population, and blood As concentrations were above the maximum allowable limit of 1 μg/L established by the ATSDR. A mutagenic activity of the drinking water was observed, and regarding the concentrations of As in water, only one sample exceeded the maximum permissible value of 10 μg/L established by the WHO. The intake of water and/or food containing As is potentially generating DNA damage in the inhabitants of the Mojana region, which requires surveillance and control by health entities to mitigate these effects.

Concentrations of essential and toxic elements and health risk assessment in brown rice from Qatari market

Twenty-two brown rice varieties available in the Qatari market were analyzed for essential and toxic elements by ICP-MS. Found concentrations (µg/kg) were: As: 171 ± 78 (62-343), Cd: 42 ± 60 (4-253), Cr: 515 ± 69 (401-639), Pb: 6 ± 7 (<MDL-26), and U: 0.1 ± 0.5 (<MDL-2). One third of the samples contained high levels of arsenic. Significant differences (p < 0.008) in concentrations were observed for many elements based on both the grains' country of origin and size. Calculated carcinogenic risk according to published speciation data of inorganic arsenic and chromium(VI) available in the literature for rice is > 1 in million, may possibly be > 1 in 10,000 based on conservatively high brown rice consumption rates of 200 g/d or 400 g/d in Qatar. These elevated risks may be applicable to specific population subgroups with diabetic conditions who consume only brown rice. Non-cancer risks are mainly derived from Mn, V, Se, and Cd with a hazard index > 1 from some brown rice samples.

A Simple and Effective Method for Speciation Analysis of 13 Arsenic Species Using HPLC on a Fluorocarbon Stationary Phase Coupled to ICP-MS

The separation properties of arsenic species was investigated using HPLC-ICP-MS with several commercially available fluorocarbon stationary phases and no ion-pair reagents in HPLC. One pentafluorophenyl column showed the highest potential for the separation of a larger number of arsenic species when using simple acid-based mobile phases. After modification of the operational parameters in HPLC, the speciation analysis of 13 representative arsenic species: arsenite, arsenate, methylarsonic acid, dimethylarsinic acid, trimethylarsine oxide, tetramethylarsonium, arsenobetaine, arsenocholine, thio-dimethylarsinic acid, oxo-arsenosugar-glycerol, oxo-arsenosugar-phosphate, oxo-arsenosugar-sulfonate, and oxo-arsenosugar-sulfate, was achieved by HPLC-ICP-MS with the column along with a mobile phase of 0.05% heptafluorobutyric acid-methanol (99:1, volume per volume).

Distribution of nutrient and toxic elements in brown and polished rice

Rice is a staple food in many countries around the world and it is a source of not only the nutrients, but also toxic elements. In this study, we evaluated four degrees of polishing and determined the elemental content (P, S, K, Mn, Fe, Ni, Cu, Zn, As, Se, Mo, Cd, Hg, Pb) in brown rice, rice bran and the resulting white rice using microwave assisted decomposition followed by inductively coupled plasma mass spectrometry (ICP-MS) detection. Additionally, individual rice grains at every polishing step were analyzed by laser ablation ICP-MS to generate elemental distribution maps. While P, K, Mn and Fe were predominantly located in bran layer, S, Cu, Zn, As, Se, Mo, Cd, and Hg were present in both the bran and endosperm. As the elemental distribution in the grain varies, polishing to produce white rice results in removal of different amounts of nutrient and toxic elements.

Determination of total arsenic content and arsenic speciation in different types of rice

The objectives of this study was to examine the amount of total arsenic and arsenic speciation in different types of rice from two areas in Korea using inductively coupled plasma/mass spectrometer (ICP-MS) and high performance liquid chromatography-ICP/MS (HPLC-ICP/MS) and estimate the potential health risk from rice consumption. Brown rice (0% of degree of polishing, DOP%) contained the highest amount of total arsenic followed by 5, 7 and 10 DOP% white rice. Among the arsenic species, As(III) was predominantly detected in brown (0 DOP%) and white rice (10 DOP%), with concentrations ranging from 28.51±0.71 to 51.91±1.13 μg/kg in region A and from 62.1 to 130.4 μg/kg in region B. While estimating the daily arsenic exposure from consumption of polished rice, the expected daily exposure of inorganic arsenic from brown and 10 DOP% white rice was found to be below benchmark dose modeling value for a 0.5% increased incidence of lung cancer (BMDL0.5) (3.0 μg/kg bw per day). Therefore, arsenic in rice, particularly, As(III), tends to accumulate in the outer layer of rice.

Inorganic Arsenic Determination in Food: A Review of Analytical Proposals and Quality Assessment Over the Last Six Years

Here we review recent developments in analytical proposals for the assessment of inorganic arsenic (iAs) content in food products. Interest in the determination of iAs in products for human consumption such as food commodities, wine, and seaweed among others is fueled by the wide recognition of its toxic effects on humans, even at low concentrations. Currently, the need for robust and reliable analytical methods is recognized by various international safety and health agencies, and by organizations in charge of establishing acceptable tolerance levels of iAs in food. This review summarizes the state of the art of analytical methods while highlighting tools for the assessment of quality assessment of the results, such as the production and evaluation of certified reference materials (CRMs) and the availability of specific proficiency testing (PT) programmes. Because the number of studies dedicated to the subject of this review has increased considerably over recent years, the sources consulted and cited here are limited to those from 2010 to the end of 2015.

Arsenic Speciation and Cadmium Determination in Tobacco Leaves, Ash and Smoke

The concentrations of arsenic (As) and cadmium (Cd) in the tobacco leaves, ash and smoke of 10 kinds of cigarettes collected from different countries worldwide were determined by ICP-MS after microwave-assisted digestion. Total As and Cd concentrations in the tobacco leaves ranged from 0.20 to 0.63 and 1.8 to 9.9 mg kg(-1), respectively. By the speciation analysis of As in tobacco leaves and ash by HPLC-ICP-MS following acid extraction, arsenite [As(III)] and arsenate [As(V)] were determined and trace amounts of monomethylarsonic acid (MMAA), dimethylarsinic acid (DMAA), trimethylarsine oxide (TMAO), tetramethylarsonium (TeMA) and some unidentified As species were also found. Arsenic speciation for smoke absorbed in an aqueous solution was carried out. The sum of the As species in tobacco leaves, ash and smoke was in good agreement with the result of total As determination in each sample, and the recoveries of speciation were 100 ± 10%. The distributions and the behaviors of As species were clarified.

Total Arsenic, Cadmium, and Lead Determination in Brazilian Rice Samples Using ICP-MS

This study is aimed at investigating a suitable method for rice sample preparation as well as validating and applying the method for monitoring the concentration of total arsenic, cadmium, and lead in rice by using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Various rice sample preparation procedures were evaluated. The analytical method was validated by measuring several parameters including limit of detection (LOD), limit of quantification (LOQ), linearity, relative bias, and repeatability. Regarding the sample preparation, recoveries of spiked samples were within the acceptable range from 89.3 to 98.2% for muffle furnace, 94.2 to 103.3% for heating block, 81.0 to 115.0% for hot plate, and 92.8 to 108.2% for microwave. Validation parameters showed that the method fits for its purpose, being the total arsenic, cadmium, and lead within the Brazilian Legislation limits. The method was applied for analyzing 37 rice samples (including polished, brown, and parboiled), consumed by the Brazilian population. The total arsenic, cadmium, and lead contents were lower than the established legislative values, except for total arsenic in one brown rice sample. This study indicated the need to establish monitoring programs for emphasizing the study on this type of cereal, aiming at promoting the Public Health.

Expression of a vacuole-localized BURP-domain protein from soybean (SALI3-2) enhances tolerance to cadmium and copper stresses

The plant-specific BURP family proteins play diverse roles in plant development and stress responses, but the function mechanism of these proteins is still poorly understood. Proteins in this family are characterized by a highly conserved BURP domain with four conserved Cys-His repeats and two other Cys, indicating that these proteins potentially interacts with metal ions. In this paper, an immobilized metal affinity chromatography (IMAC) assay showed that the soybean BURP protein SALI3-2 could bind soft transition metal ions (Cd(2+), Co(2+), Ni(2+), Zn(2+) and Cu(2+)) but not hard metal ions (Ca(2+) and Mg(2+)) in vitro. A subcellular localization analysis by confocal laser scanning microscopy revealed that the SALI3-2-GFP fusion protein was localized to the vacuoles. Physiological indexes assay showed that Sali3-2-transgenic Arabidopsis thaliana seedlings were more tolerant to Cu(2+) or Cd(2+) stresses than the wild type. An inductively coupled plasma optical emission spectrometry (ICP-OES) analysis illustrated that, compared to the wild type seedlings the Sali3-2-transgenic seedlings accumulated more cadmium or copper in the roots but less in the upper ground tissues when the seedlings were exposed to excessive CuCl2 or CdCl2 stress. Therefore, our findings suggest that the SALI3-2 protein may confer cadmium (Cd(2+)) and copper (Cu(2+)) tolerance to plants by helping plants to sequester Cd(2+) or Cu(2+) in the root and reduce the amount of heavy metals transported to the shoots.