Trace analysis of triasulfuron and bensulfuron-methyl in water samples using a carbon nanotubes packed cartridge in combination with high-performance liquid chromatography

Extraction and determination of sulfonylurea herbicides in water and soil samples by using ultrasound-assisted surfactant-enhanced emulsification microextraction and analysis by high-performance liquid chromatography

An ultrasound-assisted surfactant-enhanced emulsification microextraction (UASEME) with low-density extraction solvents was developed for the extraction of sulfonylurea herbicides from water and soil samples prior to high-performance liquid chromatography coupled with ultraviolet detection (HPLC-UV). In this technique, a surfactant was used as emulsifier which could enhance the dispersion of water-immiscible extraction solvent into aqueous phase and was favorable for the mass-transfer of the analytes from aqueous phase to organic phase. The target analytes were extracted into an extraction phase (Aliquat-336 in 1-octanol) and dispersed in an aqueous solution. After extraction and phase separation, the organic solvent on top of the solution was withdrawn into a syringe and 20 µL of it was injected into a HPLC instrument for analysis. Influential factors in extraction were investigated and optimized. Under optimum experimental conditions, calibration curve was linear in the concentration range from 1 to 100 µg/L, with coefficients of estimation (R(2) values) varying from 0.9928 to 0.9952, and satisfactory repeatabilities (4.7<RSDs%<6.1) were attained. High preconcentration factors were achieved ranging from 103 to 153. Applicability of the method to the extraction of sulfonylurea herbicides from different types of complicated matrices, such as water and soil samples, was studied. The obtained results indicated that the proposed method is efficient, fast and inexpensive for extraction and determination of sulfonylurea herbicides in environmental aqueous and soil samples.

Biodegradation of bensulphuron-methyl by a novel Penicillium pinophilum strain, BP-H-02

A fungal strain able to rapidly degrade bensulphuron-methyl (BSM), called BP-H-02, was isolated for the first time from soil that had been contaminated with BSM for several years. BP-H-02 can use BSM as the sole carbon and energy source for growth in a mineral salt medium. Based on morphological and internal transcribed spacer (ITS) analysis, BP-H-02 was identified as Penicillium pinophilum. Under optimal conditions (pH 6.5, temperature 30 °C and 200 mg/L VSSinoculum), more than 87% of the initially added BSM (50mg/L) was degraded after 60 h. Metabolites were identified as 2-amino-4,6-dimethoxypyrimidine and 1-(4,6-dimethoxypyrimidin-2-yl) urea by liquid chromatography-mass spectrometry (LC-MS), and a possible degradation pathway was deduced. In a soil bioremediation experiment, inoculation of soil with BP-H-02 promoted the degradation of BSM more effectively than did the control. These results revealed that BP-H-02 can biodegrade bensulphuron-methyl efficiently and could potentially be used to bioremediate sulphonylurea herbicides contamination.

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.

Estimating the relevance of engineered carbonaceous nanoparticle facilitated transport of hydrophobic organic contaminants in porous media

Naturally occurring nanoparticles (NP) enhance the transport of hydrophobic organic contaminants (HOCs) in porous media. In addition, the debate on the environmental impact of engineered nanoparticles (ENP) has become increasingly important. HOC bind strongly to carbonaceous ENP. Thus, carbonaceous ENP may also act as carriers for contaminant transport and might be important when compared to existing transport processes. ENP bound transport is strongly linked to the sorption behavior, and other carbonaceous ENP-specific properties. In our analysis the HOC-ENP sorption mechanism, as well as ENP size and ENP residence time, was of major importance. Our results show that depending on ENP size, sorption kinetics and residence time in the system, the ENP bound transport can be estimated either as (1) negligible, (2) enhancing contaminant transport, or (3) should be assessed by reactive transport modeling. One major challenge to this field is the current lack of data for HOC-ENP desorption kinetics.

Occurrence, behavior and effects of nanoparticles in the environment

The increasing use of engineered nanoparticles (NP) in industrial and household applications will very likely lead to the release of such materials into the environment. Assessing the risks of these NP in the environment requires an understanding of their mobility, reactivity, ecotoxicity and persistency. This review presents an overview of the classes of NP relevant to the environment and summarizes their formation, emission, occurrence and fate in the environment. The engineered NP are thereby compared to natural products such as soot and organic colloids. To date only few quantitative analytical techniques for measuring NP in natural systems are available, which results in a serious lack of information about their occurrence in the environment. Results from ecotoxicological studies show that certain NP have effects on organisms under environmental conditions, though mostly at elevated concentrations. The next step towards an assessment of the risks of NP in the environment should therefore be to estimate the exposure to the different NP. It is also important to notice that most NP in technical applications are functionalized and therefore studies using pristine NP may not be relevant for assessing the behavior of the NP actually used.

Effect of oxidation and dimensions of multi-walled carbon nanotubes on solid phase extraction and enrichment of some pesticides from environmental waters prior to their simultaneous determination by high performance liquid chromatography

In this novel study, some factors that affect the enrichment efficiency of multi-walled carbon nanotubes (MWCNTs) towards some pesticides in environmental water samples were studied. The effect of oxidation of MWCNTs with various oxidizing agents and the effect of length and external diameter of MWCNTs were investigated. Model pesticides were selected from various common categories of pesticides, viz. Atrazine, Propoxur, Methidathion. Variables optimized included external diameter and length of the MWCNT, oxidation of the MWCNT, mass of the MWCNT, volume and pH of water sample, composition and volume of eluting solvent and washing solvent. It was found that short-nitric acid oxidized-MWCNT exhibited higher enrichment efficiency, especially for Methidathion, than non-oxidized long MWCNT. The optimized SPE procedure is capable of determining Propoxur (detection limit: 220ngL(-1), linear range: 10-50ngmL(-1), <3.0% RSD), Atrazine (detection limit: 57.5ngL(-1), linear range: 10-100ngmL(-1), <2.8% RSD) and Methidathion (detection limit: 37.5ngL(-1), linear range: 10-50ngmL(-1), <2.5% RSD). Application of the optimized SPE procedure to determine the three target pesticides in real environmental waters (tap water, reservoir water and stream water) gave spike recoveries in the range of 81.0-108%.

Oxidized multiwalled carbon nanotubes as a novel solid-phase microextraction fiber for determination of phenols in aqueous samples

A simple and environmentally friendly method for determination of seven phenols using solid-phase microextraction (SPME) coupled to high-performance liquid chromatography (HPLC) has been developed. Several materials were used as stationary phase of SPME fibers and an oxidized multiwalled carbon nanotubes material was found to be effective in carrying out simultaneous extraction of phenols in aqueous samples. Compared with the widely used commercially available SPME fibers, this proposed fiber had much lower cost, longer lifetime (over 150 times), shorter analysis time (30 min of extraction and 3 min of desorption time) and comparable or superior extraction efficiency for the investigated analytes. The extraction and desorption conditions were evaluated and the calibration curves of seven phenols were linear (R(2)> or =0.9908) in the range from 10.2 to 1585 ng mL(-1). The limits of detection at a signal-to-noise (S/N) ratio of 3 were 0.25-3.67 ng mL(-1), and the limits of quantification calculated at S/N=10 were 0.83-12.25 ng mL(-1) for these compounds. The possibility of applying the proposed method to environmental water samples analysis was validated.