A simple and fast method for chlorsulfuron and metsulfuron methyl determination in water samples using multiwalled carbon nanotubes (MWCNTs) and capillary electrophoresis

Impact of nanotechnology on progress of flow methods in chemical analysis: A review

In evolution of instrumentation for analytical chemistry as crucial technological breakthroughs should be considered a common introduction of electronics with all its progress in integration, and then microprocessors which was followed by a widespread computerization. It is seems that a similar role can be attributed to the introduction of various elements of modern nanotechnology, observed with a fast progress since beginning of this century. It concerns all areas of the applications of analytical chemistry, including also progress in flow analysis, which are being developed since the middle of 20th century. Obviously, it should not be omitted the developed earlier and analytically applied planar structures like lipid membranes or self-assembled monolayers They had essential impact prior to discoveries of numerous extraordinary nanoparticles such as fullerenes, carbon nanotubes and graphene, or nanocrystalline semiconductors (quantum dots). Mostly, due to catalytic effects, significantly developed surface and the possibility of easy functionalization, their application in various stages of flow analytical procedures can significantly improve them. The application of new nanomaterials may be used for the development of new detection methods for flow analytical systems in macro-flow setups as well as in microfluidics and lateral flow immunoassay tests. It is also advantageous that quick flow conditions of measurements may be helpful in preventing unfavorable agglomeration of nanoparticles. A vast literature published already on this subject (e.g. almost 1000 papers about carbon nanotubes and flow-injection analytical systems) implies that for this reviews it was necessary to make an arbitrary selection of reported examples of this trend, focused mainly on achievements reported in the recent decade.

Amino functionalized magnetic covalent organic framework for magnetic solid-phase extraction of sulfonylurea herbicides in environmental samples from tobacco land

An amino-functionalized magnetic covalent organic framework composite TpBD-(NH2 )2 @Fe3 O4 (Tp=Tp1,3,5-triformylphloroglucinol, BD-(NH2 )2 is 3,3',4,4'-biphenyltetramine) was prepared by post-synthesis modification. Due to its abundant benzene rings and amino groups, large specific surface area and porous structure, the prepared TpBD-(NH2 )2 @Fe3 O4 exhibits high extraction efficiency toward sulfonylurea herbicides. Based on this, a new method of magnetic solid-phase extraction with TpBD-(NH2 )2 @Fe3 O4 as the sorbent combined with high-performance liquid chromatography and ultraviolet detection was developed for trace analysis of sulfonylurea herbicides in environmental water, soil and tobacco leaves samples from tobacco land. Under the optimized conditions, the limits of detection within 0.05-0.14 μg/L were achieved with a high enrichment factor of 217-260-fold, and the relative standard deviations were 4.9-7.5% (n = 7, c = 0.5 μg/L). The linear range was around three orders of magnitude with the square of correlation coefficient higher than 0.9936. The method was applied to analyze five sulfonylurea herbicides in the environmental water, soil, and tobacco leave samples collected from tobacco land. No sulfonylurea herbicides were detected in these samples. The recoveries of target sulfonylurea herbicides in spiked environmental water, soil, and tobacco leaf samples were found in the range of 90.7-104, 70.7-99.0, and 59.3-97.8%, respectively. The results illustrate that the established TpBD-(NH2 )2 @Fe3 O4 -magnetic solid-phase extraction- high-performance liquid chromatography-ultraviolet detection method is efficient for the analysis of trace sulfonylurea herbicides in environmental samples.

Anti-Agglomeration Behavior and Sensing Assay of Chlorsulfuron Based on Acetamiprid-Gold Nanoparticles

Monitoring of low levels of chlorsulfuron in environmental water samples is important. Although several detection methods have been developed, they all have some drawbacks, such as being time-consuming, requiring expensive instruments and experienced operators, and consuming large volumes of organic solvents. There is an urgent need for a simple, rapid, and inexpensive detection method for chlorsulfuron. Herein, such a method was developed using anti-aggregation of gold nanoparticles (AuNPs) in the presence of acetamiprid in agricultural irrigation water samples. Aggregation of the AuNPs was induced by acetamiprid, and this produced a distinct color change from Bordeaux red to blue. However, the strong hydrogen bonding interaction between chlorsulfuron and acetamiprid could inhibit AuNP aggregation. The effect of chlorsulfuron on the anti-agglomeration behavior of AuNPs was monitored by ultraviolet–visiblespectroscopy (UV-Vis) and the naked eye over a concentration range 0.1–100 mg/L. The detection limit for chlorsulfuron was 0.025 mg/L (signal-to-noise ratio of three). This colorimetric method was successfully applied to the determination of chlorsulfuron in spiked tap water and agricultural irrigation water with satisfactory recoveries (76.3%–94.2%).

Visual and Colorimetric Sensing of Metsulfuron-Methyl by Exploiting Hydrogen Bond-Induced Anti-Aggregation of Gold Nanoparticles in the Presence of Melamine

Various highly sensitive and selective analytical methods have been used to monitor metsulfuron-methyl residue in the environment. However, these methods involve costly instruments and complex, time-consuming operations performed in laboratories. Here, a rapid, convenient, and sensitive colorimetric sensor based on anti-aggregation of gold nanoparticles (AuNPs) is demonstrated for the rapid detection of metsulfuron-methyl in agricultural irrigation water. The AuNPs could be induced to aggregate in the presence of melamine and exhibited a distinct color change from wine-red to blue. The aggregation was suppressed by a strong hydrogen-bonding interaction between metsulfuron-methyl and melamine. The differences of the absorbance at 523 nm (ΔA523) and the color change was linearly related to metsulfuron-methyl concentration over the range 0.1⁻100 mg/L, as observed visually and by UV-vis (Ultraviolet-visible) spectrometry. The detection limit of the sensor was as low as 0.05 mg/L (signal/noise = 3), and was used to determine metsulfuron-methyl in spiked water and in agricultural irrigation water samples. Recoveries were in the range of 71.2⁻100.4%, suggesting that the colorimetric sensor was suitable for the determination of metsulfuron-methyl in agricultural water samples.

A simple voltammetric determination of metsulfuron-methyl in water samples using differential pulse cathodic stripping voltammetry

The voltammetric determination of metsulfuron-methyl, a type of pesticide, was investigated on a hanging mercury drop electrode using a differential pulse cathodic stripping voltammetry technique. The experimental parameters, such as the pH of the Britton-Robinson buffer, accumulation time, accumulation potential and initial potential were optimized for the metsulfuron-methyl determination. A well-defined reduction peak was observed at pH 2.0 to 4.0 in the potential range of -0.75 to -1.0 V. The pH of 2.0 was chosen as the optimum pH due to a good stripping signal of the reduction peak. There were no significant interfering ion effects on the electroanalysis of metsulfuron-methyl. The optimized parameters were then used to determine metsulfuron-methyl in the commercial pesticide Ally. The proposed method was highly sensitive due to the lower limit of determination (0.04 mg/L), being relatively selective, and consisting of good precision. The recovery values achieved were about 93% in water samples for this analysis.

Nanomaterials for sample pretreatment prior to capillary electrophoretic analysis

Nanomaterials are, in analytical science, used for a broad range of purposes, covering the area of sample pretreatment as well as separation, detection and identification of target molecules.

Recent Advances in the Determination of Pesticides in Environmental Samples by Capillary Electrophoresis

Nowadays, owing to the increasing population and the attempts to satisfy its needs, pesticides are widely applied to control the quantity and quality of agricultural products. However, the presence of pesticide residues and their metabolites in environmental samples is hazardous to the health of humans and all other living organisms. Thus, monitoring these compounds is extremely important to ensure that only permitted levels of pesticide are consumed. To this end, fast, reliable, and environmentally friendly methods that can accurately analyze dilute, complex samples containing both parent substances and their metabolites are required. Focusing primarily on research published since 2010, this review summarizes the use of various sample pretreatment techniques to extract pesticides from various matrices, combined with on-line preconcentration strategies for sensitivity improvement, and subsequent capillary electrophoresis analysis.

Determination of sulfonylureas in cereal samples with electrophoretic method using ionic liquid with dispersed carbon nanotubes as electrophoretic buffer

A capillary electrophoresis method to determine four sulfonylureas in grain samples was developed using 10mM of 1-butyl-3-methyl imidazolium tetrafluoroborate (bminBF4) as electrophoretic buffer solution. 2mgL(-1) of Surfactant Coated-Single Wall-Carbon Nanotubes (SC-SWCNTs) was added to the buffer solution to improve the resolution. In this way, the separation of nicosulfuron, ethoxysulfuron, sulfometuron methyl and chlorsulfuron was carried out in 16min without using organic solvents. A clean up-preconcentration procedure was done prior to inject the sample into the CE instrument, in order to achieve the established maximum residue limits (MRLs). So, the detection limits (LODs) for each analytes were between 16.8 and 26.6μgkg(-1). The relative standard deviations (RSDs) were in the range 1.9-6.7%. A recovery study using the so-called matrix matched calibration demonstrates that no matrix interferences were found throughout the determination. The recovery percentages were ranged between 80% and 113%.

Recent advances in enrichment techniques for trace analysis in capillary electrophoresis

CE is gaining great popularity as a well-established separation technique for many fields such as pharmaceutical research, clinical application, environmental monitoring, and food analysis, owing to its high resolving power, rapidity, and small amount of samples and reagents required. However, the sensitivity in CE analysis is still considered as being inferior to that in HPLC analysis. Diverse enrichment methods and techniques have been increasingly developed for overcoming this issue. In this review, we summarize the recent advances in enrichment techniques containing off-line preconcentration (sample preparation) and on-line concentration (sample stacking) to enhancing sensitivity in CE for trace analysis over the last 5 years. Some relatively new cleanup and preconcentration methods involving the use of dispersive liquid-liquid microextraction, supercritical fluid extraction, matrix solid-phase dispersion, etc., and the continued use and improvement of conventional SPE, have been comprehensively reviewed and proved effective preconcentration alternatives for liquid, semisolid, and solid samples. As for CE on-line stacking, we give an overview of field amplication, sweeping, pH regulation, and transient isotachophoresis, and the coupling of multiple modes. Moreover, some limitations and comparisons related to such methods/techniques are also discussed. Finally, the combined use of various enrichment techniques and some significant attempts are proposed to further promote analytical merits in CE.

Carbon nanotubes as sorbents in the analysis of pesticides

With increasing public concerns for agrochemicals and their potential movement in the ecosystem, very sensitive, selective and precise methods for the analysis of pesticides are needed. Because these substances are present usually at trace levels, the extraction and preconcentration steps are so far essential for their detection. Discoveries of novel nanomaterials with unique properties have significant impact on their use also in extraction techniques. This overview reports the recent application of carbon nanotubes in the analysis of pesticides. The largest numbers of reported applications of carbon nanotubes concern their role as a sorbent materials in solid-phase extraction and microextraction techniques.