Development and application of an indirect competitive enzyme-linked immunosorbent assay for the detection of p,p'-DDE in human milk and comparison of the results against GC-ECD

Antioxidant Capacity, Phytochemicals, Minerals, and Chemical Pollutants in Worker Honey Bee (Apis mellifera L.) Broods from Northern Thailand: A Safe and Sustainable Food Source

Honey bee brood (HBB) (Apis mellifera L.), a traditional protein source, has been studied for its nutritional value, but bio-functional properties and safety concerns have not been verified. This study examined the Antioxidant capacity, phytochemicals, minerals, and chemical pollutants in worker broods from several apiaries in Northern Thailand. HBB samples were lyophilized to evaluate antioxidant capacity using ABTS, DPPH, and FRAP assays, tests with water, and 70% ethanol extracts. Phytochemicals were identified using LC-QTOF-MS; pollutants were analyzed chromatographically, and minerals were determined using ICP-OES. The results showed that the evaluated antioxidant capacity of the ethanol extracts included DPPH 2.04-3.37 mg/mL, ABTS 21.22-33.91 mg/mL, and FRAP 50.07-104.15 mg AAE/100 g dry weight. Water extracts had outstanding antioxidant activities except for ABTS, with DPPH 10.67-84.97 mg/mL, ABTS 9.25-13.54 mg/mL, and FRAP 57.66-177.32 mgAAE/100 g dry weight. Total phenolics and flavonoids in ethanol extracts ranged from 488.95-508.87 GAE/100 g to 4.7-12.98 mg QE/g dry weight, respectively. Thirteen phytochemicals were detected and contained adequate mineral contents in the HBBs from different locations found, which were K, Ca, Mg, and Na, and no heavy metals or pollutants exceeded safe levels. These results imply that HBB from different apiaries in Northern Thailand is a nutritious food source with considerable antioxidants and a safe and sustainable food source.

Pesticide biosensors: trends and progresses

Pesticides, chemical substances extensively employed in agriculture to optimize crop yields, pose potential risks to human and environmental health. Consequently, regulatory frameworks are in place to restrict pesticide residue concentrations in water intended for human consumption. These regulations are implemented to safeguard consumer safety and mitigate any adverse effects on the environment and public health. Although gas chromatography- and liquid chromatography-mass spectrometry (GC-MS and LC-MS) are highly efficient techniques for pesticide quantification, their use is not suitable for real-time monitoring due to the need for sophisticated laboratory pretreatment of samples prior to analysis. Since they would enable analyte detection with selectivity and sensitivity without sample pretreatment, biosensors appear as a promising alternative. These consist of a bioreceptor allowing for specific recognition of the target and of a detection platform, which translates the biological interaction into a measurable signal. As early detection systems remain urgently needed to promptly alert and act in case of pollution, we review here the biosensors described in the literature for pesticide detection to advance their development for use in the field.

Monitoring of the Organophosphate Pesticide Chlorpyrifos in Vegetable Samples from Local Markets in Northern Thailand by Developed Immunoassay

Chlorpyrifos is an organophosphate pesticide that is wildly used among farmers for crop protection. However, there are concerns regarding its contamination in the environment and food chain. In the present study, an in-house indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) specific for detecting chlorpyrifos is developed and validated against gas chromatography–flame photometric detection (GC-FPD) as the conventional method. The developed ic-ELISA was used for detecting chlorpyrifos residue in vegetable samples. The developed ic-ELISA showed good sensitivity to chlorpyrifos at an IC₅₀ of 0.80 µg/kg, with low cross-reactivity to other organophosphate pesticides. The 160 samples were collected from local markets located in the Chiang Rai, Chiang Mai, and Nan provinces in northern Thailand. The positive rate of chlorpyrifos residues in the vegetable samples was 33.8%, with the highest levels found in cucumbers, coriander, and morning glory, at 275, 145, and 35.3 µg/kg, respectively. The highest median levels of chlorpyrifos found in the detected samples were Chinese cabbage (332 μg/kg), cucumber (146.3 μg/kg) and Chinese Kale (26.95 μg/kg). The developed ic-ELISA is suitable for the rapid quantitation of chlorpyrifos residues.

Development of a Model Immunoassay Utilizing Monoclonal Antibodies of Different Specificities for Quantitative Determination of Dieldrin and Heptachlors in Their Mixtures

The presence of dieldrin and heptachlor residues in cucurbitaceous crops at concentrations exceeding the limits set by the Japanese Food Sanitation Law constitutes a serious problem. To prevent accumulation of these residues in cucurbitaceous crops, development of high-throughput analysis methods for the detection of contaminants in the soil before cultivation is required. This study aimed to develop a model immunoassay using new monoclonal antibodies (MAbs) to quantitatively determine dieldrin and heptachlor contents in their mixtures. Three distinctive MAbs were obtained from mice immunized with the respective immunogens. MAb DrA-04 showed high reactivity toward dieldrin with ca. 20% cross-reactivity toward heptachlors. MAb DrC-02 displayed a similar reactivity toward dieldrin and heptachlors. The specificity and sensitivity of MAbs DrA-04 and DrC-02 were largely unaffected by the composition ratio of heptachlors in a mixture. Six standard mixtures with different dieldrin and heptachlor contents were prepared. Concentrations of dieldrin and heptachlors in standard mixtures, calculated on the basis of an immunoassay with MAbs DrA-04 and DrC-02, were 88.1-125 and 96.2-115% of the theoretical values, respectively, revealing excellent sensitivity and specificity of this assay. The developed method paves the way for a facile and rapid quantitative determination of chlorinated cyclodiene pesticides in soil.