Maize Samples Research Articles

Machine Learning-Mediated Ultrasensitive Detection of Citrinin and Associated Mycotoxins in Real Food Samples Discerned from a Photoluminescent Carbon Dot Barcode Array.

Economically viable remote sensing of foodborne contaminants using minimalistic chemical reagents and simultaneous automation calls for a concrete integration of a chemical detection strategy with artificial intelligence. In a first of its kind, we report the ultrasensitive detection of citrinin and associated mycotoxins like aflatoxin B1 and ochratoxin A using an Alizarin Red S (ARS) and cystamine-derived carbon dot (CD) that aptly amalgamate with machine learning algorithms for automation. The photoluminescence response of the CD as a function of various solvents and pH is used to generate array channels that are further modulated in the presence of the mycotoxins whose digital images were acquired to determine pixelation, essentially creating a barcode. The barcode was fed to machine learning algorithms that actualize and intertwine convoluted databases, demonstrating Extreme Gradient Boosting (XGBoost) as the optimized model out of eight algorithms tested. Spiked samples of wheat, rice, gram, maize, coffee, and milk were used to evaluate the testing model where an exemplary accuracy of 100% even at 10 pmol of mycotoxin concentration was achieved. Most importantly, the coexistence of mycotoxins could also be detected through the CD array and XGBoost synergy hinting toward a broader scope of the developed methodology for smart detection of foodborne contaminants.

Visual Measurement of Fumonisin B1 with Bipolar Electrodes Array-Based Electrochemiluminescence Biosensor

Fumonisin B1 (FB1) is a toxin produced by the metabolism of Fusarium oxysporum, which can cause serious effects on the nervous, respiratory, digestive, and reproductive systems of humans or animals; it is known as one of the highly toxic epidemic contaminants. Herein, we report the visual inspection of FB1 using bipolar electrodes (BPEs) with an array-based electrochemiluminescence (ECL) platform. The sensor consists of a PDMS cover and a glass substrate containing an array of 10 ITO electrodes. A specific sensing interface was constructed on the cathode of the BPE, which could modulate the ECL reactions that occurred at the anode of BPEs. To amplify the ECL signal, methylene blue (MB)-encapsulated Zr-MOFs (MB@Zr-MOFs) were synthesized and immobilized on the cathode of the BPE, which could amplify the ECL signal at the anode. By coupling the cyclic amplification effect of the DNA walker and nicking endonuclease (Nb.BbvCI), the biosensor can realize the visual measurement of FB1 in the range of 5 × 10−5~0.5 ng/mL. In addition, the developed biosensor was used to monitor the concentration of FB1 in maize and peanut samples. The recoveries were in the range of 99.2%~110.6%, which demonstrated the good accuracy of the designed BPE-ECL biosensor for FB1 assay in food samples.

Multispectral Sorting Based on Visibly High-Risk Kernels Sourced from Another Country Reduces Fumonisin and Toxigenic Fusarium on Maize Kernels

Fusarium species infect maize crops leading to the production of fumonisin by their toxigenic members. Elimination of microbes is critical in mitigating further postharvest spoilage and toxin accumulation. The current study investigates the efficacy of a previously described multispectral sorting technique to analyze the reduction of fumonisin and toxigenic Fusarium species found contaminating maize kernels in Kenya. Maize samples (n = 99) were collected from six mycotoxin hotspot counties in Kenya (Embu, Meru, Tharaka Nithi, Machakos, Makueni, and Kitui County) and analyzed for aflatoxin and fumonisin using commercial ELISA kits. Aflatoxin levels in majority (91%) of the samples were below the 10 ng/g threshold set by the Kenya Bureau of Standards and therefore not studied further. The 23/99 samples that had >2,000 ng/g of fumonisin were selected for sorting. The sorter was calibrated using kernels sourced from Ghana to reject visibly high-risk kernels for fumonisin contamination using reflectance at nine distinct wavelengths (470–1,550 nm). Accepted and rejected streams were tested for fumonisin using ELISA, and the presence of toxigenic Fusarium using qPCR. After sorting, there was a significant (p < 0.001) reduction of fumonisin, by an average of 1.8 log ng/g (98%) and ranging between 0.14 and 2.7 log ng/g reduction (28–99.8%) with a median mass rejection rate of 1.9% (ranged 0% to 48%). The fumonisin rejection rate ranged between 0 and 99.8% with a median of 77%. There was also a significant reduction (p = 0.005) in the proportion of DNA represented by toxigenic Fusarium, from a mean of 30–1.4%. This study demonstrates the use of multispectral sorting as a potential postharvest intervention tool for the reduction of Fusarium species and preformed fumonisin. The spectral sorting approach of this study suggests that classification algorithms based on high-risk visual features associated with mycotoxin can be applied across different sources of maize to reduce fumonisin.

Development and validation of a QuEChERS-LC-MS/MS method for determination of multiple mycotoxins in maize and sorghum from Botswana.

Climatic conditions such as drought, high temperatures, and pre-harvest rainfalls promote the occurrence of mycotoxins in grains. Contamination of staple food sources such as maize and sorghum means that many populations are at risk of being poisoned by mycotoxins. Hence the need for sensitive methods for their simultaneous analysis. Herein, a quick, easy, cheap, effective, rugged, and safe liquid chromatography tandem mass spectrometry (QuEChERS-LC-MS/MS) method for the simultaneous determination of ten mycotoxins in maize and sorghum is presented. The QuEChERS extraction procedure was optimized to maximize extraction recovery and minimize matrix effects while using relatively small quantities of organic solvents and acids. This method was validated according to Commission Implementing Regulation (EU) 2021/808, Commission Regulation (EC) No 1881/2006, and Regulation (EC) no. 401/2006. The developed method met the specified requirements. Recoveries of 80.77% to 109.83% and CVs below 15% were obtained. The correlation coefficient values (R2) were all above 0.98, and low limits of quantification ranging from 0.53 to 89.28 µg/Kg were recorded. The method was applied to 10 maize and 10 sorghum samples collected from markets in Botswana. Half of the samples had detectable mycotoxins, Aflatoxins, Fumonisins, T2-toxin, HT2-toxin, and Zearalenone. Two maize samples had levels of aflatoxin B1 above the maximum permitted level (2.55, 4.07 µg/Kg). These findings point to the necessity of more stringent monitoring of mycotoxins, particularly AFB1 in maize, as well as the value of regular assessment using LC-MS/MS.

Visual and Super-Sensitive Detection of Maize Chlorotic Mottle Virus by Dot-ELISA and Au Nanoparticle-Based Immunochromatographic Test Strip.

Maize chlorotic mottle virus (MCMV) is the only species in the Mahromovirus genus and is often co-infected with one or several viruses of the Potyvirus genus, posing a great threat to the global maize industry. Effective viral integrated management measures are dependent on the timely and proper detection of the causal agent of the disease. In this work, six super-sensitive and specific monoclonal antibodies (mAbs) against MCMV were first prepared using purified MCMV virions as the immunogen. Then, the Dot enzyme-linked immunosorbent assay (Dot-ELISA) was established based on the obtained mAbs, and it can detect MCMV in infected maize leaf crude extracts diluted up to 1:10,240-fold (w/v, g/mL). Furthermore, a rapid and user-friendly Au nanoparticle-based immunochromatographic test strip (AuNP-ICTS) based on paired mAbs 7B12 and 17C4 was created for monitoring MCMV in point-of-care tests, and it can detect the virus in a 25,600-fold dilution (w/v, g/mL) of MCMV-infected maize leaf crude extracts. The whole test process for ICTS was completed in 10 min. Compared with conventional reverse transcription-polymerase chain reaction (RT-PCR), the detection endpoint of both serological methods is higher than that of RT-PCR, especially the Dot-ELISA, which is 12.1 times more sensitive than that of RT-PCR. In addition, the detection results of 20 blinded maize samples by the two serological assays were consistent with those of RT-PCR. Therefore, the newly created Dot-ELISA and AuNP-ICTS exhibit favorable application potential for the detection of MCMV in plant samples.

Development of an ultrasensitive SERS aptasensor for determination of aflatoxin B1 by modifying magnetic beads with UiO-66-NH2 for enhanced signal probe capturing

A versatile Surface-enhanced Raman Spectroscopy (SERS) aptasensor was fabricated for ultrasensitive and stable aflatoxin B1 (AFB1) detection using complementary DNA strands (cDNA) modified Fe3O4@UiO-66-NH2 as capture probe and aptamer modified Au@ 4-MBA@AgNPs as signal probe. The surface of the Fe3O4 beads was functionalized with UiO-66-NH2 to improve the surface area and content of reactive amino groups for stable immobilization of cDNA and capture of more signal probes. Raman tag (4-mercaptobenzoic acid, 4-MBA) embedded Au@AgNPs nanoparticles (Au@4-MBA@AgNPs) was used as signal probes to achieve strong SERS intensity and protect the tag molecules from external interference. When no AFB1 existed, a strong SERS intensity of the signal probe was observed due to the DNA hybridization reaction between the capture and signal probe. While, the addition of AFB1 led to the dissociation of signal probes from the capture probes, leading to a decreased Raman intensity. As a result, a low limit of detection of 1.47 × 10−7 ng/mL and wide linear range from 10−6 to 102 ng/mL were obtained for determination of AFB1 based on the fabricated aptasensor. Moreover, an excellent selectivity and desirable recoveries from 94.3 % to 103.3 % in real maize samples were obtained, demonstrating the fabricated SERS aptasensor is promising in practical applications.

Rapid Detection of Single- and Co-Contaminant Aflatoxins and Fumonisins in Ground Maize Using Hyperspectral Imaging Techniques

Aflatoxins and fumonisins, commonly found in maize and maize-derived products, frequently co-occur and can cause dangerous illness in humans and animals if ingested in large amounts. Efforts are being made to develop suitable analytical methods for screening that can rapidly detect mycotoxins in order to prevent illness through early detection. A method for classifying contaminated maize by applying hyperspectral imaging techniques including reflectance in the visible and near-infrared (VNIR) and short-wave infrared (SWIR) regions, and fluorescence was investigated. Machine learning classification models in combination with different preprocessing methods were applied to screen ground maize samples for naturally occurring aflatoxin and fumonisin as single contaminants and as co-contaminants. Partial least squares–discriminant analysis (PLS-DA) and support vector machine (SVM) with the radial basis function (RBF) kernel were employed as classification models using cut-off values of each mycotoxin. The classification performance of the SVM was better than that of PLS-DA, and the highest classification accuracies for fluorescence, VNIR, and SWIR were 89.1%, 71.7%, and 95.7%, respectively. SWIR imaging with the SVM model resulted in higher classification accuracies compared to the fluorescence and VNIR models, suggesting that as an alternative to conventional wet chemical methods, the hyperspectral SWIR imaging detection model may be the more effective and efficient analytical tool for mycotoxin analysis compared to fluorescence or VNIR imaging models. These methods represent a food safety screening tool capable of rapidly detecting mycotoxins in maize or other food ingredients consumed by animals or humans.

Aflatoxin levels and Aspergillus species in maize in the Province of Isabela, Philippines

AbstractThe province of Isabela is the top maize producer in the Philippines. The intensive cultivation and the tropical climate in the region may favour fungal growth and aflatoxin contamination in maize grains. Thus, the study aimed to determine the occurrence of aflatoxin and mycotoxigenic Aspergillus species in maize varieties in this region. Samples were obtained in six municipalities from hybrid (Bt) maize (n = 101) and open‐pollinated varieties (n = 6) during the dry season (March and April) of 2019. Aflatoxin levels were quantified through enzyme‐linked immunosorbent assay, and Aspergillus species were identified through cultural and molecular methods. Aflatoxin was detected in 50.5% of maize samples; 49.5% of samples were less than the limit of detection (3 μg/kg), 16.8% with 3–20 μg/kg, 10.9% with 21–50 μg/kg and 22.8% above 50 μg/kg. Samples within the acceptable level were 66.3% for food (&lt;20 μg/kg) and 77.2% for animal feed (&lt;50 μg/kg), while 22.8% of samples were above the acceptable level of the Philippine National Standard for raw maize grains. More than 90% of Aspergillus species detected were A. flavus. Other species identified were A. tamarii and A. terreus. Despite the dry production season in the province with low relative humidity during harvesting, inadequate post‐harvest practices and the presence of A. flavus elevated the level of aflatoxin in sample grains. Additional work involving multi‐year surveys is needed to confirm the results and conclusions of this study.

A novel dual-channel immunochromatographic strip using up-conversion nanoparticles for simultaneous detection of AFB1 and ZEN in maize.

Due to universal contamination and synergistic toxicity of multiple mycotoxins in foodstuff, reliable and high-throughput detection methods for multiple mycotoxins are urgently needed in corn products. In this study, a novel dual-channel immunochromatographic assay (ICA) based on improved up-conversion nanoparticles (IUCNPs) was developed for rapidly detecting aflatoxin B1 (AFB1) and zearalenone (ZEN). The synthesized IUCNPs doped by 30% Lu3+ showed alarger size, more regular structure, and brighter fluorescence intensity than conventional UCNPs. The limits of detection (LODs) of single-channel ICA test strips for AFB1 and ZEN detection were 0.01 and 0.1ng/mL, respectively. After the optimization, the dual-channel ICA of AFB1 and ZEN in 10min was conducted, resulting in low detection limits of 0.025 and 0.1ng/mL, respectively. Moreover, the built assay was revealed to behighly specific for sixother food-contaminated mycotoxins, and exhibited excellent accuracy, with corresponding R2 of 0.9931 and 0.9982 in calibration curves, respectively. Long-term storage experiments indicated that the dual-channel test strips had superior stability and precision. The LODs of AFB1 and ZEN in spiked maize were 0.025 and 0.25μg/kg, demonstrating great sensitivity and matrix tolerance. Furthermore, the IUNCP-ICA was validated by high-performance liquid chromatography (HPLC) analyses, and a satisfactory consistency was obtained in 15 natural maize samples. Thus, the IUCNPs-ICA proposed in this work realized rapid and sensitive detection of AFB1 and ZEN, providing broad application potential in on-site screening for multiple mycotoxins in agricultural products.

Major Fusarium species and mycotoxins associated with freshly harvested maize grain in Uruguay.

Fusarium species are common fungal pathogens of maize. Fusarium graminearum and Fusarium verticillioides, among others, can cause maize ear rot, and they are also mycotoxin producers. The aims of this work were to determine the frequency and diversity of Fusarium species in Uruguayan maize kernels, evaluate the toxigenic potential of the isolates, determine toxin contamination levels on freshly harvested grain, and assess the sensitivity of main Fusarium species against fungicides. Fusarium verticillioides was the most frequent species isolated, followed by Fusarium graminearum sensu stricto. Of F. verticillioides isolates studied for fumonisin production, 72% produced fumonisin B1 and 32% fumonisin B2. Considering in vitro toxin production by F. graminearum sensu stricto isolates, deoxynivalenol was the main toxin produced, followed by zearalenone and nivalenol. Fumonisins were the most frequently found toxins on freshly harvested maize samples (98% in 2018 and 86% in 2019), and also, fumonisin B1 was the toxin with highest concentration in both years studied (4860µg/kg in 2018 and 1453µg/kg in 2019). Deoxynivalenol and zearalenone were also found as contaminants. Metconazole and epoxiconazole were the most effective fungicides tested on F. verticillioides isolates. Fusarium graminearum sensu stricto isolates also were more sensitive to metconazole compared to other fungicides; nevertheless, epoxiconazole was less efficient in controlling this species. This is the first study that reports Fusarium species and mycotoxin contamination levels associated with maize grain in Uruguay. Its detection is the main step to develop management strategies in order to minimize fungal infection in maize crops.

CRISPR/Cas12a and G-quadruplex DNAzyme-driven multimodal biosensor for visual detection of Aflatoxin B1

Aflatoxin B1 (AFB1) contamination severely threatens human and animal health, it is thus critical to construct a strategy for its rapid, accurate, and visual detection. Herein, a multimodal biosensor was proposed based on CRISPR/Cas12a cleaved G-quadruplex (G4) for AFB1 detection. Briefly, specific binding of AFB1 to the aptamer occupied the binding site of the complementary DNA (cDNA), and cDNA then activated Cas12a to cleave G4 into fragments. Meanwhile, the intact G4-DNAzyme could catalyze 3, 3′, 5, 5′-tetramethylbenzidine (TMB) to form colourimetric/SERS/fluorescent signal-enhanced TMBox, and the yellow solution produced by TMBox under acidic conditions could be integrated with a smartphone application for visual detection. The colourimetric/SERS/fluorescent biosensor yielded detection limits of 0.85, 0.79, and 1.65 pg·mL−1, respectively, and was applied for detecting AFB1 in peanut, maize, and badam samples. The method is suitable for visual detection in naturally contaminated peanut samples and has prospective applications in the food industry.

Analysis and Health Risk Evaluation of Aflatoxin B1 Levels in Groundnut (Arachis hypogea ) and Maize (Zea mays ) Samples from Wukari, Nigeria

Aflatoxin B1 (AFB1) is a secondary fungal metabolite which is considered a public health concern worldwide due to its genotoxicity and carcinogenicity. In this study, we evaluated the levels and potential health effects of AFB1 in Groundnut and Maize samples from Wukari, Nigeria. Ten samples (each) of maize and groundnuts were collected randomly from local markets and analysed for AFB1. Our findings revealed the presence of AFB1 in all the samples investigated with concentrations ranging between 7.79 – 14.08 μg/kg in groundnuts and 1.48 -15.50 μg/kg in maize samples. Overall, 90% of the analysed samples contained aflatoxin B1 above the allowed limit of 5 μg/kg. The assessment of chronic exposure and probalistic health risk from consumption of AFB1 in the investigated food samples was done via chronic daily intake (CDI) and margin of exposure (MOE) evaluations. Obtained CDI values for groundnut ranged between 14.96 – 28.74 ng·kg−1 BW day−1 for children and 3.20 – 6.15 ng·kg−1 BW day−1 for adults while for maize the values were in the range of 5.38 – 56.42 ng·kg−1 BW day−1 for children and 1.15 – 12.09 ng·kg−1 BW day−1 for adults. MOE values ranged between 3.01 – 31.60 for children and 14.06 – 147.83 for adults. The obtained MOE values are by far lower that the recommended ≥10,000 value thus indicating high carcinogenic risks to consumers of the food items. There is need to create more awareness and interventions on aflatoxin contamination of food sources in Nigeria.

Study on Selected Metals and Nutritional Status of Maize (Zea mays L.) Grown under Different Rates of Fertilizers in Wolaita Zone, Southern Ethiopia

Background: The main aim of this study was to investigate the nutritional value of maize samples grown under the different rates of blended fertilizer in Wolaita Zone, southern Ethiopia. Methods: Maize samples that were grown under combined application of the two fertilizers (K and NPSB) with ratio rates of (0:0, 25:50, 50:100, 75:150 and 100:200) kg ha-1 were used as treatment. The content of nutrients from the maize was determined by flame atomic absorption spectrometry. Result: The mean concentration of metal in the maize sample ranged as (mg/kg): Ca (512.48-725.86), K (786.62-901.907), Mg (440.23-618.61), Fe (31.52-39.63), Zn (29.45-35.58), Pb (0.005-0.034), Cd (0.014-0.13). The study also revealed that the proximate analysis of the maize sample grown under different rates of blended fertilizer ranged as moisture (5.57-9.56%), ash (0.76-2.29%), fat (2.83-5.95%), fiber (0.93-2.25), 6.83-11.86% and Carbohydrate (68.08-83.07%). For most metals and nutritional values, the highest content was obtained in maize samples grown under the application of 100 K and 200 NPSB kg per hectare.

Assessment of Maize Silage Quality under Different Pre-Ensiling Conditions

Maize silage suffers from several factors that affect the final quality and, to some extent, pre-ensiled conditions that can be potentially tuned during harvesting. After assessing new indices for silage quality under lab-scale conditions, several trials have been conducted to find associations between fresh maize characteristics and silage features. Among the first, we included field input levels, FAO class, maturity stage, use of bacterial inoculants, sealing delay and chemical traits, whereas, among the latter, we assessed density and porosity, pH, fermentative profile, dry matter loss and aerobic stability. The trials were conducted using vacuum bags or mini silo buckets. More than 1500 maize samples harvested in Northeast Italy were analysed during the 2016–2022 period. Moreover, to evaluate silage aerobic stability, the fermentative profile and temperature were measured 14 days after the opening of the silo. The association between silage quality and aerobic stability was assessed, and a prognostic risk score was used to calculate the probability of aerobic instability. The dataset could provide baseline information to promote the continuous improvement of maize silage management from different botanical and crop fields, thus improving agronomic and animal farm resource allocation from a precision agriculture perspective.

Local and Regional Dynamics of Native Maize Seed Lot Use by Small-Scale Producers and Their Impact on Transgene Presence in Three Mexican States.

Mexico harbors over 50% of maize's genetic diversity in the Americas. Native maize varieties are actively managed by small-scale producers within a diverse array of cultivation systems. Seed lot use, exchange and admixture has consequences for the in situ conservation of such varieties. Here we analyze native maize seed management dynamics from 906 small-scale producers surveyed in three Mexican states: Mexico City, Oaxaca and Chiapas. Furthermore, we analyze how their management practices can relate to transgene presence, which was experimentally documented for maize samples associated with the applied surveys. Through a data mining approach, we investigated which practices might be related with a higher probability of transgene presence. The variables found to have a strong spatial association with transgene presence were: for Mexico City, maize producers with larger parcels; for Oaxaca, producer's age (43-46 years) and the sale of seed; for Chiapas, the use of agricultural machinery and younger producers (37-43 years). Additionally, transgene presence and frequency within the socioeconomic regions of Oaxaca and Chiapas was analyzed. In Oaxaca, higher transgene frequencies occurred in regions where transgene presence had been previously reported. In Chiapas, the border regions with Guatemala as well as a region where reproduction of improved seed takes place, the highest proportion of positive samples were found. A detailed mapping of regional seed markets and seed exchange sites together with deployment of national and local biosecurity measures, could help prevent the further spread of transgenes into native maize varieties, as well as improve conservation efforts.

Deposition, Dietary Exposure and Human Health Risks of Heavy Metals in Mechanically Milled Maize Flours in Mbarara City, Uganda.

Consumption of maize and maize-based products contributes a significant percentage to the total food energy intake in Uganda. However, the production of maize-derived foodstuffs is performed traditionally or by small- and medium-scale processors using different processing techniques. This can lead to differences in the quality of these products from processors, raising food safety concerns. In this study, the effects of mechanical processing (milling) methods on deposition of heavy metals into milled maize flour and the associated consumption health risks were assessed. Atomic absorption spectrophotometry was used to quantitatively establish the concentration of iron (Fe), manganese (Mn), zinc (Zn), cadmium (Cd), lead (Pb), chromium (Cr), copper (Cu), cobalt (Co) and nickel (Ni) in 100 samples of maize milled using a wooden mortar (n = 2), a metallic mortar (n = 2), diesel engine-powered mills (n = 48) and electric motor-powered mills (n = 48). Results showed that the mean concentrations of heavy metals in mg/kg were Fe (11.60-34.45), Cu (0.50-8.10), Ni (0.50-1.60), Mn (0.70-25.40), Zn (4.40-15.90), Pb (0.53-10.20), Cd (0.51-0.85), Cr (0.50-1.53) and Co (0.50-1.51). The highest concentrations were found in flour milled using a traditional metallic mortar while the lowest levels were in those samples milled using a wooden mortar. The Fe, Pb and Cd contents of flours produced using the metallic mortar and some commercial mills was found to be higher than the permissible limits set by WHO/FAO. Human health risk assessment showed that there are potential carcinogenic health risks from adults' intake of heavy metals in maize flour milled using a metallic mortar. Therefore, processing of maize flour needs to be monitored by the relevant statutory bodies in Uganda to minimize the possibility of heavy metal contamination of food products and animal feeds.

Analysis of tetrabromobisphenol A and bisphenol A in plant sample-method optimization and identification of the derivatives.

Tetrabromobisphenol A (TBBPA) is the most abundant brominated flame retardant and bisphenol A (BPA) is often identified as the metabolic product of TBBPA. Both of them are highly bioconcentrated and show serious biological toxicity. In this study, an analytical method was optimized to simultaneously determine TBBPA and BPA in plant samples. Moreover, the uptake and metabolism of TBBPA in maize were investigated through hydroponic exposure experiment. The whole analysis procedure included ultrasonic extraction, lipid removal, purification by solid-phase extraction cartridge, derivatization, and detection by GC/MS. Optimizations were conducted for each pretreatment step above. After improvement, methyl tert-butyl ether (MTBE) was chosen as the extraction solvent; the lipid removal was conducted by repartition between organic solvent and alkaline solution. The best suitable pH condition is 2-2.5 for the inorganic solvent before used for further purification by HLB and silica column with the optimized elute solvent of acetone and mixtures of acetone and hexane (1:1), respectively. The recoveries of TBBPA and BPA spiked in maize samples were 69±4% and 66±4% with the relative standard deviation less than 5%, respectively, for the entire treatment procedure. Limits of detections were 4.10 ng/g and 0.13 ng/g for TBBPA and BPA in plant samples, respectively. In the hydroponic exposure experiment (100 μg/L, 15 d), the concentrations of TBBPA in maize cultivated in pH 5.8 and pH 7.0 Hoagland solutions were 1.45 and 0.89 μg/g in roots and 8.45 and 6.34 ng/g in stems, while they were all below the detection limit for leaves, respectively. The distribution of TBBPA in different tissues was as the following order: root>>stem>leaf, illustrating the accumulation in the root and the translocation to the stem. The uptake variations under different pH conditions were attributed to the change of TBBPA species, now that it shows greater hydrophobicity at lower pH condition as a kind of ionic organic contaminant. Monobromobisphenol A and dibromobisphenol A were identified as metabolisms products of TBBPA in maize. The efficiency and simplicity of the method that we proposed characterize its potential application as a screening tool for environmental monitoring and contribute to a comprehensive study of the environmental behavior of TBBPA.

Detection Aflatoxin on the Imported Maize (Zea mays L) Using HPLC in the Areas of Baghdad

This study was conducted in the laboratory of fungi of the Department of biology of the collage of Science in Mustansiriyah University to investigate the contamination of grain (maize ) displayed in the markets of the city of Baghdad mycotoxins type aflatoxin, was isolated the fungi associated with contamination of maize and the number of 10 isolates where the record Aspergillus flavus isolates the most isolates occur 7 Aspergillus niger isolates followed by 2 isolates and one isolated Penicillium sp. ، Aspergillus flavus isolates done Pathogenicity test to identify the isolates of the study. Four isolates were identified (Afla1, Afla2, Afla3, Afla4). The results of the aflatoxin detection in four different samples of positive yellow maize samples showed that all samples tested were contaminated with Aflatoxin, sampled from different regions, Adhamiya, Al-shaab and Palestine Street, had the highest pollution rate of 2149μg/g for Afla 1, while Afla 2 recorded the lowest pollution rate of 114μg/g.

Magnetic relaxation switching immunoassay based on “limited-magnitude” particles for sensitive quantification of aflatoxin B1

Aflatoxin B1 (AFB1) is a highly toxic and carcinogenic chemical substance that endangers food safety and human health. Magnetic relaxation switching (MRS) immunosensors are utilized in a variety of applications in food analysis due to its resistance to matrix interferences, but they often suffer from magnetic separation-based multi-washing steps and low sensitivity. Herein, we propose novel MRS strategy for the sensitive detection of AFB1 using “Limited-Magnitude” size particles: a single millimeter sized polystyrene spheres (PSmm) and 150 nm superparamagnetic nanoparticles (MNP150). Only a single PSmm is used as the microreactor to enhance all of the magnetic signal on its surface in high concentration by an immune competitive response, successfully preventing signal dilution, which can be transferred by pipette, simplifying the process of separation and washing. The established single polystyrene sphere magnetic relaxation switch biosensor (SMRS) was able to quantify AFB1 from 0.02 to 200 ng/mL with a detection limit of 14.3 pg/mL. SMRS biosensor has been successfully used for the detection of AFB1 in wheat and maize samples, and the results in agreement with high performance liquid chromatography-tandem mass spectrometry (HPLC-MS). Benefiting from high sensitivity and convenient operation, the simple and enzyme-free method is promising in trace small molecules applications.

Influence of macronutrients and micronutrients on maize hybrids for biogas production

Important in the cultivation of corn for biogas production is the selection of appropriate hybrids, macro- and micronutrient dozing and the evaluation of energy and economic efficiency of their use. Therefore, this article presents the results of 3-year field research (2019–2021) on the yield of maize hybrids of different maturity groups grown for silage. The influence of the application of macronutrients and micronutrients on fresh and dry mass yield, chemical composition, methane yield, energy, and economic efficiency was analysed. It was established that depending on the maize hybrid, the application of macro- and micro-fertilizers increased the yield of the fresh mass of maize by 1.4–24.0% compared to options without their use. The evaluation of the theoretical yield of CH4 based on the content of fats, protein, cellulose, and hemicellulose is also presented in different samples of maize. The findings show that the application of macro-and micro-fertilizers is suitable from the energy and economic points of view — profitability begins to appear at the price of biomethane of 0.3–0.4 euros per 1 m3.