Determination of toxic and potentially toxic elements in rice and rice-based products by inductively coupled plasma-mass spectrometry

Rapid simultaneous quantification of arsenic and lead in grain using improved monochromatic excitation energy dispersive X-ray fluorescence spectrometry

In most cases, conventional energy dispersive X-ray fluorescence (EDXRF) analysis of trace arsenic (As) and lead (Pb) in grains encounters technical difficulties due to sensitivity challenges and the overlapping of characteristic X-ray lines. By utilizing high-definition X-ray technology and doubly curved crystal (DCC), along with establishing interference correction models for As and Pb, we can significantly improve analytical sensitivity for specific portions of the spectrum while reducing interference. This study demonstrates that the improved monochromatic excitation energy dispersive X-ray fluorescence spectrometry (MEDXRF), combined with an algorithmic analysis of fundamental parameters (FP), exhibits higher sensitivity compared to existing EDXRF methods. This improvement is achieved by optimizing the DCC structure, device geometry layout, and detection conditions. The detection limits, precision, and accuracy of MEDXRF for As and Pb were evaluated using certified reference materials (CRMs) and actual grain samples. The test results indicate that the limits of detection (LODs) were generally better than those specified by the Codex general standard, with values of 0.02 mg/kg for As and 0.03 mg/kg for Pb. The accuracy and precision were in good agreement with ICP-MS results. Therefore, the enhanced MEDXRF method offers sufficient sensitivity, accuracy and stability for the direct determination of As and Pb in grains below food safety limits.

High Sensitivity and Selectivity of PEDOT/Carbon Sphere Composites for Pb2+ Detection

Heavy metal ions impair human health and irreversibly damage the ecosystem. As a result, it is critical to create an efficient approach for identifying heavy metal ions. The electrochemical sensor method is a type of detection method that is highly sensitive, low in cost, and allows for real-time monitoring. In this study, solid carbon spheres were made using resorcinol and formaldehyde as raw materials, followed by the formation of PEDOT/carbon sphere composites via in situ oxidative polymerization, and Pb2+ was detected utilizing them as electrode modification materials. The structure of the PEDOT/carbon spherical composites was analyzed using scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). To investigate the electrochemical properties of these composites, electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and differential pulse voltammetry (DPV) were employed. In addition, the detection mechanism of the material for Pb2⁺ was studied using CV. The PEDOT/carbon sphere sensor showcased an extensive linear detection range of 7.5 × 10-2 to 1.0 μM for Pb2+ ions, achieving a low limit of detection (LOD) of 3.5 × 10-2 nM and displaying exceptional selectivity. These results can be attributed to its large surface area, superior electrical conductivity, and outstanding electron transport properties. This study offers an effective material for detecting low concentrations of Pb2+, with potential applications in future Pb2+ detection.

Potential toxic elements in breakfast cereals in the Kurdistan region, Iraq

Potential toxic elements are substances that can accumulate in foodstuffs and pose risks to human health even at low levels, or when their levels exceed safety thresholds. A total of 78 breakfast cereals were purchased from the Kurdistan region, Iraq. Their PTE levels were analysed and associated health risks were calculated. The levels of As, Cd, Pb, Cu and Cr ranged from 0.055 ± 0.02-0.12 ± 0.05 mg/kg, 0.024 ± 0.009-0.08 ± 0.03 mg/kg, 0.015 ± 0.003-0.12 ± 0.06 mg/kg, 1.93 ± 0.5-3.9 ± 0.1 mg/kg and 0.36 ± 0.02-0.84 ± 0.1 mg/kg, respectively. The PTE levels were mostly below the Codex Alimentarius maximum limits, except in 11 samples, which exceeded the limits for As, Cd and Pb. Risk assessment data of HQ and HI (below 1) showed no non-carcinogenic health risks for both adults and children. However, due to the high levels of As, Cd and Pb in some samples, continuous monitoring is advisable to ensure the constant quality of these products.

Rice sample preparation method for ICP-MS and CV-AFS analysis: Elemental levels and estimated intakes

Eight sample digestion procedures were compared to determine 41 elements in rice samples by ICP-MS and CV-AFS. Analytical methods were evaluated using certified rice flour reference material (NIST 1568b) and recovery experiments. The microwave-assisted digestion of 0.5 g rice sample and reagent mixture of 2 mL HNO3, 0.5 mL H2O2, and 0.5 mL deionized water yielded the best recovery for all elements ranging from 90 to 120% at three different levels, bias% within 10%, and precision (coefficient of variation percent, CV% intra- and inter-day) below 15%. The best analytical method was applied to the elemental determination in nine types of rice available on the Italian market. Daily or weekly rice consumption meets the nutritional and safety requirements of EFSA and WHO. The present study allows extensive and detailed knowledge of the content of essential and non-essential/toxic elements in different types of rice produced or packaged in Italy.

The development and validation of a new method for the fast determination of Al, Ba, Ca, Cu, Fe, K, Mg, Mn, Na, Sr and Zn in rice by inductively coupled plasma optical emission spectrometry

An alternative method of rice sample preparation for measuring the total content of selected elements, i.e., Al, Ba, Ca, Cu, Fe, K, Mg, Mn, Na, Sr and Zn, by ICP OES was developed. The proposed approach is based on the ultrasound-assisted extraction (USAE) of rice samples in the presence of a small amount of concentrated HNO3. The optimal operating parameters were found using the design of experiments (DOE) approach, and the studied experimental factors were the temperature of the ultrasonic bath (A), the sonication time (B), and the volume of concentrated HNO3 added per 0.5 g of a rice sample (C). Under the optimal conditions of the USAE procedure, i.e., A = 60 °C, B = 16 min and C = 4.0 mL, the rice samples were readily solubilized, and the obtained sample solutions could be analyzed by ICP OES with the simple standard solution calibration (without matrix matching). The analysis of the certified reference material (rice flour, NIST SRM 1568b) confirmed the satisfactory trueness of the USAE-ICP OES method. Additionally, no statistically significant differences between the results obtained for the samples prepared by USAE and open-vessel wet digestion (WD, the reference method) were found. In comparison to the routinely used microwave-assisted digestion and open-vessel digestion, the USAE approach offers lower acid consumption, lower detection limits (LODs) of elements, ranging from 4.0 ng g-1 for Mn to 2.7 µg g-1 for K, and a much shorter time of sample preparation.

Elemental composition of toxic and essential elements in rice-based baby foods from the United States and other countries: A probabilistic risk analysis

Consumption of rice-based foods provides essential nutrients required for infants and toddlers' growth. However, they could contain toxic and excess essential elements that may affect human health. The study aims to determine the composition of rice-based baby foods in the USA and outside and conduct a multiple-life stages probabilistic exposure and risk assessment of toxic and essential elements in children. Elemental concentrations were measured using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) in thirty-three rice-based baby foods. This includes 2 infant formulas, 11 rice baby cereals, and 20 rice snacks produced primarily in the United States, China, and other countries. A probabilistic risk assessment was conducted to assess risks of adverse health effects. Results showed that infant formula had higher median concentrations of selenium (Se), copper (Cu), zinc (Zn), sodium (Na), magnesium (Mg), calcium (Ca), and potassium (K) compared to rice baby cereal and rice snacks. On the contrary, rice snacks had the highest median concentration of Arsenic (As) (127 μg/kg) while rice baby cereals showed the highest median concentration of Cd (7 μg/kg). A higher lifetime estimated daily intake was observed for samples manufactured in the USA compared to those from China and other countries. Hazard quotient (HQ < 1) values were suggestive of minimal adverse health effects. However, lifetime carcinogenic risk analysis based on total As indicated an unacceptable cancer risk (>1E-04). These findings show a need for ongoing monitoring of rice-based foods consumed by infants and toddlers as supplementary and substitutes for breast milk or weaning food options. This can be useful in risk reduction and mitigation of early life exposure to improve health outcomes.

Essential and Toxic Elements in Infant Cereal in Brazil: Exposure Risk Assessment

Infant cereals, one of the first solid foods introduced to infants, have been reported to pose risks to human health because they contain toxic elements and an excess of essential elements. The objective of this study was to assess the cancer and non-cancer risk of exposure to essential and toxic elements in infant cereal in Brazil. In our analyses, we included data from 18 samples of infant cereals made from different raw materials and estimated the incremental lifetime cancer risks and non-cancer hazard quotients (HQs) for their consumption. Rice cereal is particularly concerning because it is immensely popular and usually contains high levels of inorganic arsenic. In addition to arsenic, we assessed aluminum, boron, barium, cadmium, chromium, copper, lead, manganese, nickel, selenium, silver, strontium, and zinc. The cancer risk was highest for rice cereal, which was also found to have an HQ > 1 for most of the tested elements. Inorganic As was the element associated with the highest cancer risk in infant cereal. All of the infant cereals included in this research contained at least one element with an HQ > 1. The essential and non-essential elements that presented HQ > 1 more frequently were zinc and cadmium, respectively. The cancer and non-cancer risks could potentially be decreased by reducing the amount of toxic and essential elements (when in excess), and public policies could have a positive influence on risk management in this complex scenario.

Replacing manual operation with bio-automation: A high-throughput evolution strategy to construct an integrated whole-cell biosensor for the simultaneous detection of methylmercury and mercury ions without manual sample digestion

Methylmercury is primarily responsible for most food mercury pollution cases. However, most biosensors developed for mercury pollution analysis can only detect mercury ions. Although oxidative strong-acid digestion or microwave-assisted digestion can convert methylmercury into mercury ions, it is unsuitable for on-site detection. This study designed a bio-digestion gene circuit and integrated it into a mercury ion whole-cell biosensor，creating a novel on-site methylmercury detection method. Five alkyl mercury lyases from different bacterial genomes were screened via bioinformatics analysis, of which goMerB from Gordonia otitis showed the highest catalytic biological digestion efficiency. The goMerB site-specific saturation and random mutation libraries were constructed. After two rounds of high-throughput visualization screening, the catalytic activity of the mutant increased 2.5-fold. The distance between the three crucial amino acid sites and methylmercury changed in the mutant, which likely contributed to the enhanced catalytic efficiency. The optimized whole-cell biosensor showed a linear dynamic concentration range of 100 nM to 100 μM (R2 =0.991), satisfactory specificity, and interference resistance. The detection limit of the goMerBt6-MerR-RFP biosensor was 0.015 μM, while the limit of quantitation was 0.049 μM. This study demonstrated the application of synthetic biology for food safety detection and highlighted the future potential of "Lab in a Cell" for hazard analysis.

Portable smartphone-integrated AuAg nanoclusters electrospun membranes for multivariate fluorescent sensing of Hg2+, Cu2+ and l-histidine in water and food samples

Detection of heavy metals have been pivotal due to their non-biodegradability and food chain accumulation. Herein, a multivariate ratiometric sensor was developed by in situ integrating AuAg nanoclusters (NCs) into electrospun cellulose acetate nanofibrous membranes (AuAg-ENM) for visual detection of Hg²⁺, Cu²⁺ and consecutive sensing of l-histidine (His), which was integrated into a smartphone platform for quantitative on-site detection. AuAg-ENM achieved multivariate detection of Hg²⁺ and Cu²⁺ by fluorescence quenching, and subsequent selective recovery of the Cu²⁺-quenched fluorescence by His, which distinguished Hg²⁺ and Cu²⁺ and fulfilled determination of His simultaneously. Notably, AuAg-ENM achieved selective monitoring of Hg²⁺, Cu²⁺ and His in water, food and serum samples with high accuracy comparable to ICP and HPLC tests. A logic gate circuit was devised to further explain and promote the application of AuAg-ENM detection by smartphone App. This portable AuAg-ENM provides a promising reference for fabricating intelligent visual sensors for multiple detection.

Metal(loid) Analysis of Commercial Rice from Malaysia using ICP-MS: Potential Health Risk Evaluation

Rice is a predominant staple food in many countries. It is a great source of energy but can also accumulate toxic and trace metal(loid)s from the environment and pose serious health hazards to consumers if overdosed. This study aims to determine the concentration of toxic metal(loid)s [arsenic (As), cadmium (Cd), nickel (Ni)] and essential metal(loid)s [iron (Fe), selenium (Se), copper (Cu), chromium (Cr), cobalt (Co)] in various types of commercially available rice (basmati, glutinous, brown, local whites, and fragrant rice) in Malaysia, and to assess the potential human health risk. Rice samples were digested following the USEPA 3050B acid digestion method and the concentrations of metal(loid)s were analyzed using an inductively coupled plasma mass spectrometry (ICP-MS). Mean concentrations (mg/kg as dry weight) of metal(loid)s (n=45) across all rice types were found in the order of Fe (41.37)>Cu (6.51)>Cr (1.91)>Ni (0.38)>As (0.35)>Se (0.07)>Cd (0.03)>Co (0.02). Thirty-three percent and none of the rice samples surpassed, respectively, the FAO/WHO recommended limits of As and Cd. This study revealed that rice could be a primary exposure pathway to toxic metal(loid)s, leading to either noncarcinogenic or carcinogenic health problems. The non-carcinogenic health risk was mainly associated with As which contributed 63% to the hazard index followed by Cr (34%), Cd (2%), and Ni (1%). The carcinogenic risk to adults was high (>10-4) for As, Cr, Cd, and Ni. The cancer risk (CR) for each element was 5 to 8 times higher than the upper limit of cancer risk for an environmental carcinogen (<10-4). The findings from this study could provide the metal(loid)s pollution status of various types of rice which are beneficial to relevant authorities in addressing food safety and security-related issues.

Ln Based Metal-organic Framework for Fluorescence "Turn Off-On" Sensing of Hg2

A highly luminescent Ln-MOF [La₃(NDC)₄(DMF)₃(H₂O)₄]_n, (NDC = 2, 6 naphthalen dicarboxylic acid) was designed and synthesized. The structure was characterized by x-ray single structure determination, TGA, IR spectra and PXRD and fluorescence spectroscopy. The structure shows high fluorescence intensity based on the presence of lanthanide metal and ligand. In the presence of I^-, the emission can be effectively quenched introducing turn off system. Furthermore, the synthesized Ln-MOF can recognize Hg (II) by showing fluorescence turn-on signal because of the high affinity between Hg (II) and I^-. Moreover, the high selectivity and sensitivity of the synthesized Ln-MOF makes it quit qualified for determination of the low concentration of mercury (2.00 nM).

An insight into the act of iron to impede arsenic toxicity in paddy agro-system

Surplus research on the widespread arsenic (As) revealed its disturbing role in obstructing the metabolic function of plants. Also, the predilection of As towards rice has been an interesting topic. Contrary to As, iron (Fe) is an essential micronutrient for all life forms. Past findings propound about the enhanced As-resistance in rice plants during Fe supplementation. Thus, considering the severity of As contamination and resulting exposure through rice crops, as well as the studied cross-talks between As and Fe, we found this topic of relevance. Keeping these in view, we bring this review discussing the presence of As-Fe in the paddy environment, the criticality of Fe plaque in As sequestration, and the effectiveness of various Fe forms to overcome As toxicity in rice. This type of interactive analysis for As and Fe is also crucial in the context of the involvement of Fe in cellular redox activities such as oxidative stress. Also, this piece of work highlights Fe biofortification approaches for better rice varieties with optimum intrinsic Fe and limited As. Though elaborated by others, we lastly present the acquisition and transport mechanisms of both As and Fe in rice tissues. Altogether we suggest that Fe supply and Fe plaque might be a prospective agronomical tool against As poisoning and for phytostabilization, respectively.

Elemental Analysis of Solid Food Materials Using a Reliable Laser Ablation Inductively Coupled Plasma Mass Spectrometry Method

Quantification of trace and minor nutrient elements is crucial for maintaining human health. A reliable laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) method for food materials was developed by combining fine food powder (d_m < 3 μm) pellets as the external standard with an average C content as the internal standard (IS). The finer and homogeneous aerosol produced by ablating the fine powder pellets is beneficial for transportation and analyte ionization in ICP, which helps alleviate the matrix effects and improves the analytical precision and accuracy. The average C content is 39.9 ± 1.9% for plant-derived foods (n = 22) and 46.9 ± 1.1% for animal-derived foods (n = 7). The accuracy (recovery, 80-120%) and precision (RSD, 0.5-9.8%) were validated by analyzing a series of food certified reference materials. The high-throughput method is a promising alternative for routine sample analysis in food safety laboratories.

Origin of the effects of optical spectrum and flow behaviour in determining the quality of dry fig, jujube, pomegranate, date palm and concentrated grape vinegars

In this study, we focused on physical characterization and quality control of dry fig, jujube, pomegranate, date palm and concentrated grape vinegars using UV spectroscopy method and rheology technique. The optical spectra and flow behaviour of the vinegars were analysed in detail in the selected specific wavelength, shear rate and frequency ranges, respectively. It was determined that the peak values seen in the UV spectra of the vinegars were caused by the organic acid and phenolic compound concentration. The peak values in the UV spectra of the vinegars wavelength range of 190 nm to 240 nm and 250 nm to 300 nm were caused by the organic acid and phenolic compound concentration, respectively. In this context, it was predicted that concentrated grape vinegar, which has the highest absorbance value, has higher organic acid content and more antibacterial/antioxidant properties compared to the others. It is thought that the optical energy gaps of vinegars are related to the organic acid concentration and the release time. Flow properties of the vinegars were non-Newtonian thickening fluids (dilatant fluids) and compatible with the Power law model. The stable flow of the vinegars in the high shear rate region was interpreted as having a successful production process and being of good quality.

Development of a DNAzyme-based colorimetric biosensor assay for dual detection of Cd2+ and Hg2

A colorimetric biosensor assay has been developed for Cd²⁺ and Hg²⁺ detection based on Cd²⁺-dependent DNAzyme cleavage and Hg²⁺-binding-induced conformational switching of the G-quadruplex fragment. Two types of multifunctional magnetic beads (Cd-MBs and Hg-MBs) were synthesized by immobilizing two functionalized DNA sequences on magnetic beads via avidin-biotin chemistry. For Cd²⁺ detection, Cd-MBs are used as recognition probes, which are modified with a single phosphorothioate ribonucleobase (rA) substrate (PS substrate) and a Cd²⁺-specific DNAzyme (Cdzyme). In the presence of Cd²⁺, the PS substrate is cleaved by Cdzyme, and single-stranded DNA is released as the signal transduction sequence. After molecular assembly with the other two oligonucleotides, duplex DNA is produced, and it can be recognized and cleaved by FokI endonuclease. Thus, a signal output component consisting of a G-quadruplex fragment is released, which catalyzes the oxidation of ABTS with the addition of hemin and H₂O₂, inducing a remarkably amplified colorimetric signal. To rule out false-positive results and reduce interference signals, Hg-MBs modified with poly-T fragments were used as Hg²⁺ accumulation probes during the course of Cd²⁺ detection. On the other hand, Hg-MBs can perform their second function in Hg²⁺ detection by changing the catalytic activity of the G-quadruplex/hemin DNAzyme. In the presence of Hg²⁺, the G-quadruplex structure in Hg-MBs is disrupted upon Hg²⁺ binding. In the absence of Hg²⁺, an intensified color change can be observed by the naked eye for the formation of intact G-quadruplex/hemin DNAzymes. The biosensor assay exhibits excellent selectivity and high sensitivity. The detection limits for Cd²⁺ and Hg²⁺ are 1.9 nM and 19.5 nM, respectively. Moreover, the constructed sensors were used to detect environmental water samples, and the results indicate that the detection system is reliable and could be further used in environmental monitoring. The design strategy reported in this study could broadly extend the application of metal ion-specific DNAzyme-based biosensors.

Green Labelled Rice Shows a Higher Nutritional and Physiochemical Quality Than Conventional Rice in China

In China, green food refers to a wide array of certified agricultural and processed edible commodities that are produced strictly following defined standard protocols and labelled with a specified “Green Food” logo. The demand for green labelled rice is rapidly growing due to its higher quality and adherence to safety standards compared to conventional rice. Therefore, the physicochemical and nutritional quality of green rice needs to be further investigated for consumers’ benefits. Using Daohuaxiang 2, one of the most famous types of green rice, we found that green rice was significantly superior to conventional rice in terms of thousand kernel weight, chalkiness, amylose content, and rheological properties. Green rice contained lower levels of heavy metals than conventional rice due to a dramatic reduction in chemical inputs during its cultivation. The concentrations of Cr, As, Cd, Pb in green rice decreased, respectively, from 98.7 to 180.1 μg/kg, 49.8 to 62.3 μg/kg, 7.8 to 9.1 μg/kg, and 29.0 to 42.8 μg/kg on average. Gas chromatography coupled with mass spectrometry (GC–MS)-based metabolomics, in combination with multivariate analysis, revealed that 15 metabolites differentially accumulated when comparing green and conventional rice. Among these, 12 metabolites showed a high accumulation in green rice, including seven amino acids, two sugars, and three fatty acids. Overall, our results suggest the superior quality of a type of green rice that is popular in China, which may boost green rice consumption and facilitate the further expansion of green rice production in China.

Content of Toxic Elements in 12 Groups of Rice Products Available on Polish Market: Human Health Risk Assessment

Background: Rice is one of the most commonly consumed grains. It could be a good source of nutrients in a diet, but its consumption could also contribute to exposure to toxic elements. All rice products available on the Polish market are imported, which may pose a particular concern as to the safety of their consumption. The aim of our study was to estimate the content of As, Cd, Pb, and Hg in rice products and to assess the health risk indicators related to exposure to toxic elements consumed with rice products among the adult population in Poland. Methods: A total of 99 samples from 12 groups of rice products (basmati, black, brown, parboiled, red, wild, white rice and expanded rice, rice flakes, flour, pasta, and waffles) available in the Polish market were obtained. The content of Hg was determined using the atomic absorption spectrometry method (AAS). To measure As, Cd, and Pb, inductively coupled plasma-mass spectrometry (ICP-MS) was used. The health risk was assessed by calculating several indicators. Results: The average As, Cd, Pb, and Hg contents in all studied products were 123.5 ± 77.1 μg/kg, 25.7 ± 26.5 μg/kg, 37.5 ± 29.3 μg/kg, and 2.8 ± 2.6 μg/kg, respectively. Exceedance of the limit established by the Polish National Food Safety Standard was observed in one sample as regards the As content and exceedance of the European Commission standard in two samples for Hg. The samples of foods imported from European markets (n = 27) had statistically higher As content (p < 0.05) than those imported from Asian countries (n = 53). The values of health risk indicators did not show an increased risk for the Polish adult population. However, the daily intake of 55 g of rice corresponds to the benchmark dose lower confidence limit (BMDL) for Pb. Conclusion: The studied rice products could be regarded as safe for consumption by the Polish population as far as the content of As, Cd, Pb, and Hg is concerned.

Assessment of potential human health risk of trace element in wild edible mushroom species collected from Yunnan Province, China

Wild edible mushrooms are rich in nutritions and popular among people, but wild edible mushrooms easily accumulate potentially harmful trace elements, and excessive intake will harm health. The aim of this study was to investigate the potential health hazards of long-term intake of wild edible mushrooms in Yunnan Province, China. The concentrations of trace element (As, Cd, Cr, Cu, Hg, Pb, Ni, and Zn) in 19 species of wild edible mushrooms in Yunnan Province were determined by inductively coupled plasma mass spectrometry (ICP-MS). Further processing of the data, the potential health risk assessments of consumers were evaluated by the target hazard quotient (THQ), hazard index (HI), and incremental lifetime cancer risk (ILCR), respectively. Results showed that concentrations of trace element in wild edible mushrooms decreased in the order of Zn > Cu > As > Ni > Cr > Cd > Pb > Hg. Compared with the maximum standard by the WHO/China, the averages of As, Cd, Cr, Hg, and Zn were significantly greater than the standard. Among the tested wild edible mushrooms, HI values of Leccinum crocipodium, Thelephora ganbajun, Lactarius luteolus, Tricholoma matsutake, and Polyporus ellisii were more than 1. Thus, Leccinum crocipodium, Thelephora ganbajun, Lactarius luteolus, Tricholoma matsutake, and Polyporus ellisii are the main sources of risk. The value of THQ in ascending order was as follows: Pb (0.11) < Cd (0.75) < As (4.27) < Hg (6.87). Thus, Hg are the primary sources of health risk in the wild edible mushrooms in Yunnan Province. ILCR_(As) values of Thelephora ganbajun, Tricholoma matsutake, Laccaria amethystea, and Polyporus ellisii were more than 10^-4, these four samples are the primary sources of health risk. The mean values of ILCR for As in wild mushroom were 1.01 × 10^-4. The results suggest that there was potential health risk to the consumer associated with the long-term consumption of wild edible mushrooms collected from Yunnan Province. We propose that the concentrations of trace element should be periodically monitored in wild edible mushrooms.

Heavy metals and probabilistic risk assessment via rice consumption in Thailand

In this study, heavy metals including Cr, Mn, Co, Ni, Cu, Zn, As, and Cd in 55 Thai local rice (4 varieties) were measured using ICP-MS. Health risks were estimated from various Thai population groups, classified according to ages and genders. The potential impact on Thai population who consumed Thai local rice contained heavy metals was assessed by means of probabilistic approach. The hazard quotient (HQ) for non-carcinogenic risks from heavy metal exposure was below the threshold limit of 1 for all rice varieties except Mn in Pka Am Pun rice and As in Pka Am Pun rice, Jek Chuey Sao Hai rice, and Leb Nok rice. Only the hazard index (HI) for consumption of Khaowong Kalasin sticky rice was below 1. The maximum cancer probabilities over the lifetime consumption of Thai local rice were in the range of 5 in 10,000 to 3 in 1000 chances in developing cancer.

Determination of the Total Content of Arsenic, Antimony, Selenium and Mercury in Chinese Herbal Food by Chemical Vapor Generation-Four-Channel Non-dispersive Atomic Fluorescence Spectrometry

Food security is related to safe and nutritious food which meets people's dietary needs and food preferences for an active and healthy life. A simple and feasible method was proposed for the simultaneous analysis of trace arsenic (As), antimony (Sb), selenium (Se) and mercury (Hg) in Chinese herbal food by chemical vapor generation coupled non-dispersive atomic fluorescence spectrometry (CVG-NDAFS) in this paper. The operating parameters, such as observation height, carrier and shield gas flow rate, were optimized. The detection limits were obtained under optimal conditions, which were 0.051, 0.034, 0.050 and 0.0058 ng mL^-1, respectively for As, Sb, Se and Hg. The relative standard deviations were 0.42%, 0.74%, 0.97% and 1.0% (n = 7), respectively (10 ng mL^-1of As, Sb, Se and 1 ng ml^-1of Hg). The proposed method is verified to simultaneously determine As, Sb, Se and Hg for Chinese herbal food.

Tuning of the Amount of Se in Rice (Oryza sativa) Grain by Varying the Nature of the Irrigation Method: Development of an ICP-MS Analytical Protocol, Validation and Application to 26 Different Rice Genotypes

The amount of specific trace elements like selenium (Se) may be of health concern for humans if contained in too high (or low) quantities in staple foods like rice. Among the attempts aimed to optimize the Se concentration in rice, only few studies have been focused on the use of irrigation methods other than continuous flooding. Since intermittent irriguous methods, like sprinkler and saturation, have found to be effective in modifying the bioaccumulation of arsenic and cadmium in rice kernels, the main goal of this study is to measure the amount of the total Se contained in grains of 26 rice genotypes cultivated for two consecutive agrarian vintages in the same open field and with the same water, but differently irrigated with continuous flooding, sprinkler or saturation. To do this, an original and validated ICP-MS method has been developed. The validation parameters accounted for a high sensitivity and accuracy. Sprinkler irrigation is able to reduce in the average of 90% the amount of total Se in kernels in comparison to values measured in rice irrigated with continuous flooding. In conclusion, different irrigation techniques and rice genotypes seem to be valuable tools in order to allow in the future the customized modulation of the Se concentration in rice grain according to the needs of the various populations.

Versatile Sensing Platform for Cd2+ Detection in Rice Samples and Its Applications in Logic Gate Computation

A versatile sensing platform was designed for Cd²⁺ detection utilizing Mg²⁺-dependent DNAzyme as the biocatalyst and toehold-mediated strand replacement as the reaction mechanism. The Cd²⁺-aptamer interaction brings the split subunits of the Mg²⁺-dependent DNAzyme into close-enough proximity, which generates an active DNAzyme that can catalyze the cleavage reaction toward the hairpin substrate strand (H1). The trigger DNA fragment in H1 can open another hairpin probe (H2) to activate the cyclic signal amplification process. The generated numerous G-quadruplex DNAzyme structures will produce a high fluorescence response after incubation with the fluorescence dye N-methyl mesoporphyrin IX (NMM). This detection platform is ultrasensitive and the detection limit (LOD) is 2.5 pM (S/N = 3). The sensing system is robust and can work effectively even in a complex sample matrix, enabling the quantitative analysis of Cd²⁺ content in rice samples with good reliability. Showing the unique features of simple operation, label-free and enzyme-free format, high sensitivity and selectivity, and universal signal amplification mode, our proposed sensing protocol holds great promise for becoming a competitive alternative for the routine monitoring of Cd²⁺ pollution. Importantly, this flexible and versatile sensing platform was used to construct some exquisite logic gates, including AND, OR, INHIBIT, IMPLICATION, NOR, and NAND.

Rapid determination of cadmium in rice by portable dielectric barrier discharge-atomic emission spectrometer

In this work, a home-made portable dielectric barrier discharge-atomic emission spectrometer (DBD-AES) was explored to the determination of heavy metal in foodstuffs. A rapid and simple method was developed for Cd determination in rice based on this instrument. Rice was pretreated with diluted acid dissolution without complex operations and apparatus. The detection time by DBD-AES is about 3 min and the total analysis time for rice sample is within 11 min. The effects of some key experiment parameters were investigated. The limit of detection was 11.9 μg kg^-1 for Cd in rice, much lower than the maximum allowable level established by EC (200 μg kg^-1). The practical performance of this method was demonstrated by analyzing real and CRM rice samples. With the portability of DBD-AES, the method is suitable for rapid and in-field analysis of Cd in rice. It will be a useful tool for the routine analysis of rice.

Highly Selective, Aptamer-Based, Ultrasensitive Nanogold Colorimetric Smartphone Readout for Detection of Cd(II)

A highly selective and sensitive method for Cd(II) detection was developed based on aptamer and gold nanoparticles (AuNPs) combined with a colorimetric smartphone readout. The experimental conditions such as reaction time of polydiene dimethyl ammonium chloride (PDDA) and AuNPs, PDDA dose, time of aptamer and PDDA incubation, and aptamer concentration were optimized. Under the optimized conditions, the color and red(R) value of the solution was concentration-dependent on Cd(II). The proposed method exhibited a linear range of 1-400 ng/mL (r² = 0.9794) with a limit of detection (LOD) of 1 ng/mL. This method had been successfully applied to test and quantify Cd(II) in water and rice samples, and the results were in full agreement with those from the atomic absorption spectrometer. Therefore, low-cost colorimetry demonstrated its potential for practical application in visual or quantitative detection with a smartphone. This approach can be readily applied to other analytes.

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.