This study describes the variation in residue behavior of fluopyram in soil, carrot root, and carrot leaf samples after the application of fluopyram (41.7% suspension, Bayer) by foliar spray or root ...irrigation at the standard of 250.00 g active ingredient per hectare (a.i./ha) and double-dose treatment (500.00 g a.i./ha). Fluopyram and its metabolite fluopyram-benzamide were extracted and cleaned up using the QuEChERS method and subsequently quantified with LC-QQQ-MS/MS. The LOD and LOQ of the developed method were in the range of 0.05–2.65 ug/kg and 0.16–8.82 ug/kg, respectively. After root irrigation, the final residues detected in edible parts were 0.60 and 1.80 mg/kg, respectively, when 250.00 and 500.00 g a.i./ha were applied, which is much higher than the maximum residue limit in China (0.40 mg/kg). In contrast, after spray application, most of the fluopyram dissipated from the surface of carrot leaves, and the final residues in carrot roots were both only 0.05 mg/kg. Dietary risk assessments revealed a 23–40% risk quotient for the root irrigation method, which was higher than that for the foliar spray method (8–14%). This is the first report comparing the residue behavior of fluopyram applied by root irrigation and foliar spray. This study demonstrates the difference in risk associated with the two application methods and can serve as a reference for the safe application of fluopyram.
An electrochemical sensor based on molecularly imprinted polypyrrole (MIPPy) was developed for selective and sensitive detection of the herbicide glyphosate (Gly) in cucumber and tap water samples. ...The sensor was prepared via synthesis of molecularly imprinted polymers on a gold electrode in the presence of Gly as the template molecule and pyrrole as the functional monomer by cyclic voltammetry (CV). The sensor preparation conditions including the ratio of template to functional monomers, number of CV cycles in the electropolymerization process, the method of template removal, incubation time, and pH were optimized. Under the optimal experimental conditions, the DPV peak currents of hexacyanoferrate/hexacyanoferrite changed linearly with Gly concentration in the range from 5 to 800 ng mL
−1
, with a detection limit of 0.27 ng mL
−1
(
S/N
= 3). The sensor was used to detect the concentration of Gly in cucumber and tap water samples, with recoveries ranging from 72.70 to 98.96%. The proposed sensor showed excellent selectivity, good stability and reversibility, and could detect the Gly in real samples rapidly and sensitively.
Graphical abstract
Schematic illustration of the experimental procedure to detect Gly using the MIPPy electrode
Hidden ingredients in plant protection products (PPPs) threaten public health, food trade, and the environment. In this study, we developed a high-throughput screening method of 639 hidden ...ingredients in PPPs using GC-MS/MS in multiple reaction monitoring mode. Results showed that the qualitative criteria of retention time (tR) shift and uncertainty of qualifier to quantifier ratio in the commercially available Shimadzu Smart Pesticides Database were set at < 0.17 min and < 30%, respectively, which could be used to tentatively identify compounds without standards. The limits of quantification were 0.01–0.05 mg/kg. A wide linear range of 10–1000 μg/L was observed with R2 ≥ 0.975. Recoveries from three types of PPP formulations were 62.08%− 126.3%, with relative standard deviations < 15.7%. Finally, this method was applied to screen and quantify hidden ingredients in 91 plant protection products (PPPs) samples collected from online sales in China. Only one hidden ingredient, dimethomorph (1.6 g/kg), was detected in the polyoxin formulation (15% wettable powder). The results will be helpful in assessing the potential risks of hidden ingredients in PPPs.
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•A high-throughput screening method for 639 hidden ingredients was established.•Qualitative criteria were set based on ion ratio and retention time shift.•91 plant protection products of three types of formulations were investigated.•One hidden ingredient dimethomorph was detected in biopesticide products.
Particle size distribution (PSD) is an important parameter that is relevant to many aspects of marine ecosystems, such as phytoplankton functional types, optical absorption and scattering from ...particulates, sediment fluxes, and carbon export. However, only a handful of studies have documented the PSD variability in different regions. Here, we investigate the PSD properties and variability in two shallow and semi-enclosed seas (the Bohai Sea (BS) and Yellow Sea (YS)), using in situ laser diffraction measurements (LISST-100X Type C) and other measurements at 79 stations in November 2013. The results show large variability in particle concentrations (in both volume and number concentrations), with volume concentrations varying by 57-fold. The median particle diameter (Dv50) from each of the water samples also covers a large range (22.4-307.0 mu m) and has an irregular statistical distribution, indicating complexity in the PSD. The PSD slopes (2.7-4.5), estimated from a power-law model, cover nearly the entire range reported previously for natural waters. Small mineral particles (with large PSD slopes) are characteristic of near-shore waters prone to sediment resuspension by winds and tides, while large biological particles (with small PSD slopes) dominate the total suspended particulates for waters away from the coast. For the BS and YS, this study provides the first report on the properties and spatial variability of the PSD, which may influence the optical properties of the ocean surface and remote sensing algorithms that are based on estimations of particle concentrations and sizes.
A rapid detection method is introduced for residual trace levels of triazophos in water and agricultural products using an immunoassay based on catalytic hairpin self-assembly (CHA). The gold ...nanoparticle (AuNPs) surface was modified with triazophos antibody and sulfhydryl bio-barcode, and an immune competition reaction system was established between triazophos and its ovalbumin-hapten (OVA-hapten). The bio-barcode served as a catalyst to continuously induce the CHA reaction to achieve the dual signal amplification. The method does not rely on the participation of enzymes, and the addition of fluorescent materials in the last step avoids interfering factors, such as a fluorescence burst. The emitted fluorescence was detected at 489/521 nm excitation/emission wavelengths. The detection range of the developed method was 0.01–50 ng/mL for triazophos, and the limit of detection (LOD) was 0.0048 ng/mL. The developed method correlates well with the results obtained by LC–MS/MS, with satisfactory recovery and sensitivity. In sum, the designed method is reliable and provides a new approach to detect pesticide residues rapidly and quantitatively.
Graphical Abstract
We report on a method for the determination of the herbicide atrazine in tap water samples using melamine-modified gold nanoparticles (Mel-AuNPs). If a solution containing atrazine is added to a ...solution of such NPs, a color change occurs from wine-red to blue. This is due to a transition from monodisperse to aggregated Mel-AuNPs and caused by strong hydrogen bonding between atrazine and melamine. The color change can be monitored by a UV–vis spectrophotometer or with bare eyes. The ratio of the absorbances at 640 and 523 nm is linearly related to the logarithm of the atrazine concentration in the 0.165 to 16.5 μM range, and (with different slope) in the 16.5 μM to 330 μM range. The detection limit of atrazine is as low as 16.5 nM (S/N = 3). The method was successfully applied to the determination of atrazine in spiked tap water and gave recoveries that ranged from 72.5 % to 102.3 %.
Graphical Abstract
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Suspended particles in waters play an important role in determination of optical properties and ocean color remote sensing. To link suspended particles to their optical properties and thereby remote ...sensing reflectance (Rrs(λ)), cross-sectional area is a key factor. Till now, there is still a lack of methodologies for derivation of the particle cross-sectional area concentration (AC) from satellite measurements, which consequently limits potential applications of AC. In this study, we investigated the relationship between AC and Rrs(λ) based on field measurements in the Bohai Sea (BS) and Yellow Sea (YS). Our analysis confirmed the strong dependence of Rrs(λ) on AC and that such dependence is stronger than on mass concentration. Subsequently, a remote sensing algorithm that uses the slope of Rrs(λ) between 490 and 555 nm was developed for retrieval of AC from satellite measurements of the Geostationary Ocean Color Imager (GOCI). In situ evaluations show that the algorithm displays good performance for deriving AC and is robust to uncertainties in Rrs(λ). When the algorithm was applied to satellite data, it performed well, with a coefficient of determination of 0.700, a root mean squared error of 2.126 m−1 and a mean absolute percentage error of 40.7%, and it yielded generally reasonable spatial and temporal distributions of AC in the BS and YS. The satellite-derived AC using our algorithm may offer useful information for modeling the inherent optical properties of suspended particles, deriving the water transparency, estimating the particle composition and possibly improving particle mass concentration estimations in future.
There is increasing interest for chemiluminescence (CL) detection with the characteristics of simplicity, low cost and high sensitivity, especially wide application of enhancersin CL detection to ...increased signals, prolonged luminescence time and enhanced intensity. In this review, the applications of primary enhancers and secondary enhancers were mainly described in the horseradish peroxidase-luminol system of CL enzyme immunoassay for light delay in the course of the reaction with improved sensitivity. The present review on enhancers covers the papers since 1983. Future research needs to develop novel enhancers with less interference and better performance. With wide utilization of enhancers in the CL system, the CL immunodetection technology showed a good potential and wide development prospects in food and medicine fields.
In this study, a monoclonal antibody (mAb) specific to forchlorfenuron (CPPU) with high sensitivity and specificity was produced and designated (9G9). To detect CPPU in cucumber samples, an indirect ...enzyme-linked immunosorbent assay (ic-ELISA) and a colloidal gold nanobead immunochromatographic test strip (CGN-ICTS) were established using 9G9. The half-maximal inhibitory concentration (IC
) and the LOD for the developed ic-ELISA were determined to be 0.19 ng/mL and 0.04 ng/mL in the sample dilution buffer, respectively. The results indicate that the sensitivity of the antibodies prepared in this study (9G9 mAb) was higher than those reported in the previous literature. On the other hand, in order to achieve rapid and accurate detection of CPPU, CGN-ICTS is indispensable. The IC
and the LOD for the CGN-ICTS were determined to be 27 ng/mL and 6.1 ng/mL. The average recoveries of the CGN-ICTS ranged from 68 to 82%. The CGN-ICTS and ic-ELISA quantitative results were all confirmed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) with 84-92% recoveries, which indicated the methods developed herein are appropriate for detecting CPPU in cucumber. The CGN-ICTS method is capable of both qualitative and semiquantitative analysis of CPPU, which makes it a suitable alternative complex instrument method for on-site detection of CPPU in cucumber samples since it does not require specialized equipment.
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