Triazines In Water Samples Research Articles

Hydrophobic natural deep eutectic solvents based on L-menthol as supported liquid membrane for hollow fiber liquid-phase microextraction of triazines from water and urine samples

This work proposes the use of a hydrophobic natural deep eutectic solvent (NADES) as a supported liquid membrane (SLM) for hollow fiber liquid phase microextraction (HF-LPME) of triazines. NADES were prepared using L-menthol as hydrogen bond acceptor combined with different hydrogen bond donors of natural origin: carboxlylic acids, alcohols and amines. Studies were carried out to determine whether the prepared NADES met the necessary requirements to be used as a SLM, such as stability in the HF and compatibility with HPLC. Then, the ability of each prepared NADES to extract 6 triazine herbicides by HF-LPME from aqueous samples was evaluated. Among them, the mixture L-menthol: formic acid (molar ratio 1:2) provided better extraction results and was selected as SLM. The influence the different parameters on extraction efficiency such as pH of both sample and acceptor solution, salting-out effect, extraction time and stirring rate on the extraction efficiency was carefully studied and optimized. The optimized HF-LPME procedure was applied to the analysis of aqueous samples such as artificial water containing humic acids, tap water, river water and urine, with excellent clean-up ability for all samples analyzed. Relative recoveries ranged from 68 to 128 %, and the LODs and LOQs obtained for the 6 triazines were 0.75–3.1 µg/L and 2.5–10.3 µg/L, respectively, depending on the analyte and the kind of sample. Additionally, according to the AGREEprep tool assessment, the proposed method appears as a greener approach compared to other microextraction methods reported in the literature for the analysis of triazines in water samples.

Investigation of pH-switchability of hydrophobic deep eutectic solvents for the extraction and preconcentration of triazine herbicides in water samples

An environmental friendly, fast, easy, inexpensive and dispersive-solvent-free liquid–liquid microextraction (LLME) based on pH-switchable hydrophobic deep eutectic solvent (HDES) procedure was developed and combined with high performance liquid chromatography–ultraviolet (HPLC − UV) detection for the extraction and analysis of triazine herbicides in water samples. In this method, 10 different DESs were prepared and then their pH-switchability was investigated. DESs that could be switched with pH were employed for separation and preconcentration of triazine herbicides in water samples. In this method, dispersing the extractant phase in the aqueous solution and subsequent phase separation is done only by changing the pH. Important parameters affecting extraction, such as type of DES and its volume, concentration of KOH, volume of HCL, effect of salt and extraction time were investigated and optimum conditions were obtained. In optimized conditions, the values of relative standard deviations (RSDs) for intra-day and inter-day of the procedure based on seven replicate analysis of 100 μg L–1 of triazines in water samples were 1.9–4.4 and 2.7–6.2%, respectively. The calibration graphs were linear ranging from 0.5 to 350 μg L–1 with correlation coefficients (r2) better than 0.990. The limit of detections (LODs) and limit of quantifications (LOQs) were 0.2–0.5 and 0.5–1.5 μg L–1, respectively. The relative recoveries (RRs) of real water samples which have been spiked with different levels of triazines were 91–107.8%.

Vortex-assisted solid-phase extraction based on metal-organic framework/chitosan-functionalized hydrophilic sponge column for determination of triazine herbicides in environmental water by liquid chromatography-tandem mass spectrometry

In the presented work, MIL-101(Cr) and chitosan were directly embedded on the skeleton of melamine sponge material using a simple and environmentally friendly method. Chitosan acts not only as an adhesive during the preparation of functionalized sponges, but also as an adsorption adjuvant in herbicide detection. Unlike other polymers, chitosan has excellent hydrophilicity and contains numerous adsorption sites; thus, it enables the sponge material to be used for determination of contaminants in an aqueous phase. Scanning electron microscopic (SEM) analysis showed that the coating material was uniformly distributed on the skeleton of melamine sponge. The prepared material was used as a sorbent in a vortex-assisted solid-phase extraction and combined with high performance liquid phase tandem mass spectrometry for the extraction and trace determination of six triazines in water samples (Atraton, Desmetryn, Prometon, Ametryn, Prometryn and Dimethametryn). Several parameters that affect the extraction efficiencies were investigated. Under the optimal conditions (MIL-101(Cr) loading, 150 mg; sample pH, 7; salt concentration, 0%; adsorption time, 3 min; desorption solvent, 1.5 mL acetonitrile; desorption time, 4 min), the proposed method was successfully used in the determination of trace triazines in five real water samples (drinking water, tap water, lake waters and river water), satisfactory recoveries were obtained in the range of 78.9%–118.6%. The limits of detection of the proposed method in detecting triazine herbicides in spiked water samples ranged from 0.014 to 0.045 ng mL−1.

Packed in-tube solid phase microextraction with graphene oxide supported on aminopropyl silica: Determination of target triazines in water samples

ABSTRACTOn-line in-tube solid phase microextraction (in-tube SPME) coupled to high performance liquid chromatography and tandem mass spectrometry (HPLC-MS/MS) was successfully applied to the determination of selected triazines in water samples. The method based on the employment of a packed column containing graphene oxide (GO) supported on aminopropyl silica (Si) showed that the extraction phase has a high potential for triazines extraction aiming to its physical-chemical properties including ultrahigh specific surface area, good mechanical and thermal stability and high fracture strength. Injection volume and loading time were both investigated and optimized. The method validation using Si-GO to extract and concentrate the analytes showed satisfactory results, good sensitivity, good linearity (0.2–4.0 µg L−1) and low detection limits (1.1–2.9 ng L−1). The high extraction efficiency was determined with enrichment factors ranging from 1.2–2.9 for the lowest level, 1.3–4.9 intermediate level and 1.2–3.0 highest level (n = 3). Although the analytes were not detected in the real samples evaluated, the method has demonstrated to be efficient through its application in the analysis of spiked triazines in ground and mineral water samples.

Effective extraction of triazines from environmental water samples using magnetism-enhanced monolith-based in-tube solid phase microextraction

This article reports on the effective extraction of triazines from environmental water samples using magnetism-enhanced monolith-based in-tube solid phase microextraction (ME-MB/IT-SPME). Firstly, monolithic poly (octyl methacrylate-co-ethyleneglycol dimethacrylate) capillary column doped with magnetic nanoparticles was synthesized inside a fused silica. After that, the monolithic capillary column was placed inside a magnetic coil that allowed the exertion of a variable magnetic field during adsorption and desorption steps. The effects of intensity of magnetic field, adsorption and desorption flow rate, volume of sample and desorption solvent, pH value and ionic strength in sample matrix on the performance of ME-MB/IT-SPME for triazines were investigated in details. Under the optimized conditions, the developed ME-MB/IT-SPME showed satisfactory quantitative extraction efficiencies of the target analytes between 64.8% and 99.7%. At the same time, the ME-MB/IT-SPME was combined with high-performance liquid chromatography with diode array detection to detect six triazines in water samples. The limits of detection (S/N = 3) and limits of quantification (S/N = 10) were in the ranges of 0.074–0.23 μg/L and 0.24–0.68 μg/L, respectively. The precision of the proposed method was evaluated in terms of intra- and inter-assay variability calculated as relative standard deviation, and it was found that the values were all below 10%. Finally, the developed method was successfully applied for environmental water samples such as farmland, lake and river water with spiked recoveries in the range of 70.7–119%.

Development of Solid Phase Micro Extraction Technique for Determination of Triazines in Water Samples Using Experimental Design

Development of Solid Phase Micro Extraction Technique for Determination of Triazines in Water Samples Using Experimental Design

Double water compatible molecularly imprinted polymers applied as solid-phase extraction sorbent for selective preconcentration and determination of triazines in complicated water samples

In the present work, double water compatible molecularly imprinted polymers (DWC-MIPs) with water compatible core and hydrophilic polymer brushes were prepared by reversible addition–fragmentation chain transfer precipitate polymerization (RAFTPP) and applied as solid-phase extraction (SPE) sorbent for selective preconcentration and specific recognition of triazines in water samples. The DWC-MIPs employed as SPE sorbent presented much higher extraction efficiency for four triazines in aqueous media based on the double water compatible property. The validated method was also successfully applied to tap water and river water sample analysis, and satisfactory recoveries were attained, such as 69.2–95.4% with the precision of 1.59–3.94% for four triazines at 100μgL−1. The DWC-MIPs-SPE proves to be a highly effective cleanup and enrichment method for simultaneous separation and sensitive determination of triazines in complicated water samples.

A comparison between emulsification of reverse micelle-based supramolecular solvent and solidification of vesicle-based supramolecular solvent for the microextraction of triazines

Two approaches based on emulsification of reverse micelle-based supramolecular solvent microextraction (ERM-SSME) and solidification of vesicle-based supramolecular solvent microextraction (SV-SSME) were compared for the extraction and preconcentration of four triazines (cyanazine, simazine, prometon and propazine) from water samples. Different ERM-SSME and SV-SSME parameters influencing the extraction efficiency were studied and optimized. The results showed that both extraction methods exhibited good linearity, precision, enrichment factor, and detection limit. Under optimal conditions, the limits of detection were 0.3 and 0.5μgL−1 for ERM-SSME and SV-SSME, respectively. The enrichment factors were from 330 to 505 and 285 to 421 for ERM-SSME and SV-SSME, respectively. The applicability of the proposed methods was examined by analyzing triazines in water samples and good results were obtained.

On-fibre solid-phase microextraction coupled to conventional liquid chromatography versus in-tube solid-phase microextraction coupled to capillary liquid chromatography for the screening analysis of triazines in water samples

This paper compares the advantages and disadvantages of two different configurations for the extraction of triazines from water samples: (1) on-fibre solid-phase microextraction (SPME) coupled to conventional liquid chromatography (LC); and (2) in-tube SPME coupled to capillary LC. In-tube SPME has been effected either with a packed column or with an open capillary column. A critical evaluation of the main parameters affecting the performance of each method has been carried out in order to select the most suitable approach according to the requirements of the analysis. In the on-fibre SPME configuration the fibre coating was polydimethylsiloxane (PDMS)–divinylbenzene (DVB). The limits of detection (LODs) obtained with this approach under the optimized extraction and desorption conditions were between 25 and 125 μg/L. The in-tube SPME approach with a C 18 packed column (35 mm × 0.5 mm I.D., 5 μm particle size) connected to a switching micro-valve provided the best sensitivity; under such configuration the LODs were between 0.025 and 0.5 μg/L. The in-tube SPME approach with an open capillary column coated with PDMS (30 cm × 0.25 mm I.D., 0.25 μm of thickness coating) connected to the injection valve provided LODs between 0.1 and 0.5 μg/L. In all configurations UV detection at 230 nm was used. Atrazine, simazine, propazine, ametryn, prometryn and terbutryn were selected as model compounds.

Optimisation of a solid-phase microextraction procedure for the determination of triazines in water with gas chromatography–mass spectrometry detection

A procedure based on solid-phase microextraction (SPME) and gas chromatography–mass spectrometry, operating in the chemical ionisation mode, was developed and optimised in order to determine 10 triazines in water samples. Five different SPME fibers available for analysis [polydimethylsiloxane (PDMS) 100 μm, polyacrylate (PA) 80 μm, PDMS–divinylbenzene (DVB) 65 μm, Carbowax (CW)–DVB 65 μm, and Carboxen (CAR)–PDMS 75 μm] were tested, and PDMS–DVB was selected. To enhance the sensitivity of the SPME, variables affecting adsorption and desorption steps such as temperature, time, pH and ionic strength of the solution were optimised. Detection limits obtained were ranged between 2 and 17 ng l −1, and precision values were below 8% for the selected PDMS–DVB fiber. The optimised method was applied to real water samples and no triazines were detected.

Determination of chlorotriazines, methylthiotriazines and one methoxytriazine by SPE–LC–UV in water samples

Triazine herbicides form a wide group of substances that belong among the most common agrochemicals applied for pre- and post-emergence weed control. So, they can be found in the environment at trace level. In order to determine their concentrations in water samples by the usual analytical techniques, a preconcentration step is commonly necessary. In this paper, a simple analytical method for the quantification of eight triazines (three chlorotriazines, four methylthiotriazines and one methoxytriazine) in water samples by solid phase extraction-reversed phase liquid chromatography (LC) has been developed. LC shows good analytical performance for simultaneous multiple triazine analysis (repeatability <2%, reproducibility <3%), except for prometon (repeatability 5.52%, reproducibility 16%). The results, obtained by using carbograph and polymeric sorbents for solid phase extraction (SPE), have been compared. The limits of quantification achieved permit the application of the proposed SPE–LC method for the determination of eight triazines in water samples (0.0065–0.028 μg l −1).

Determination of triazines in water samples by high-performance liquid chromatography with diode-array detection.

Triazines are widely used herbicides that can be detected in the environment at trace level. A preconcentration step is necessary to determinate them before analysis. In this study, carbonaceous and polymeric adsorbents are compared with C18 for the solid-phase extraction of simazine, atrazine, and propazine in water samples in order to quantitate their levels by high-performance liquid chromatography using photodiode-array detection.

Development of a highly sensitive enzyme-immunoassay for the determination of triazine herbicides

A monoclonal antibody (Mab) with extraordinary sensitivity and high class selectivity to triazine herbicides is described. With an enzyme-linked immunosorbent assay (ELISA) using Mab 4A54 IC50 values for terbuthylazine, atrazine, propazine and simazine below 0.1 μg/L (the EU maximum admissible concentration for individual pesticides) have been obtained. Detection limits of 0.004 μg/L for terbuthylazine, 0.006 μg/L for atrazine, 0.003 μg/L for propazine, 0.01 μg/L for simazine and 0.05 μg/L for deethylterbuthylazine could be achieved. Therefore, Mab 4A54 allows a sum screening of these five triazines in a relevant concentration range. To our knowledge, this is the most sensitive antibody to terbuthylazine at all and also the most sensitive Mab to all these four triazines. Another monoclonal antibody resulting from the same immunization, clone 4A118, exhibits best sensitivity for propazine (detection limit: 0.02 μg/L) at lower cross-reactivity to terbuthylazine and atrazine compared to clone 4A54. Affinity constants of both Mabs towards several triazines have been calculated. The application of both Mabs for the analysis of triazines in water samples of different origin has been tested and their resistance towards humic acid influence could be shown. A good correlation of the analysis of water samples with GC and ELISA was observed.

On-line solid-phase extraction in liquid chromatography using restricted access pre-columns for the analysis of s-triazines in humic-containing waters

A coupled-column liquid chromatographic system using solid-phase extraction pre-columns for the seven chlorotriazines, atrazine, desethylatrazine, desisopropylatrzine (DIA), propazine, simaize, desthylterbythylazine and terbuthylazine, using photodiode-array detection (PDAD) was developed. Restricted access (RA), was investigated as a pre-column material, making use of non-adsorptive size exclusion of macromolecules and simultaneous dynamic portioning of the analytes, for the pre-concentration in environmental analysis. The RA phase was characterized and shown to solve problems with difficult matrix effects in humic-containing surface water samples. Other pre-column materials, e.g. reversed-phase C 18, mono-functional C 18, extraction disk mixture of C 18 and styrene-divinylbenzene (PS-DVB) and LiChrolut EN, a polymeric sorbent specially designed for environmental analysis, were investigated and compared for their selectivity and stability, respectively. Comparisons were made with respect to selectivity and efficiency for the SPE columns separately and in combination with analytical columns. Recovery data and matrix dependencies were studied at concentration levels ranging between 0.1–10 μg/1. The RA pre-columns showed superior stability in complex environmental matrices, such as reference humic water and river water, due to the restriction of macromolecules. Retention properties with the RA alkyl-diol-silica were not sufficient for the most polar metabolites. However, efficient sorption/desorption kinetics were found with medium-polar and non-polar compounds. LiChrolut EN was found to strongly retain these polar metabolites as well as medium and non-polar solutes, and was selected for a deeper investigation (e.g. salinity dependence and pH). For a 10×2 mm I.D. pre-column, the breakthrough volume for the polar metabolite DIA was at least 150 ml, while for the RA pre-columns it was less than 10 ml. Unfortunately, this polymeric support was strongly effected, in terms of stability, in complex matrices which lead to repeated and expensive exchanging of pre-columns. However, in order to detect even the polar metabolites these pre-columns were finally used on-line together with liquid chromatography PDAD and thermospray mass spectrometry for the determination of triazines in water samples from the Ebro river during different seasons of the year.

Validation of commercially available ELISA microtiter plates for triazines in water samples

Comparative trials were carried out on triazine microtiter plate tests distributed by Millipore, Riedel-de Haën, Transia and CIFEC. Sensitivity and reproducibility were tested with standard solutions of atrazine. Cross-reactivity was studied for hydroxyatrazine, deisopropylatrazine, deethylatrazine, simazine, hydroxysimazine, terbutylazine, hydroxyterbutylazine and deetylterbutylazine. A set of 19 surface-, 16 ground- and 6 lysimetric plate water samples were also analysed. Liquid chromatography with diode array detection or gas chromatography with nitrogen-phosphorus detection were used as validated control techniques for those natural samples. Laboratory assays developed by GEC-Marconi as part of a collaborative European Union research project (BIOPTICAS) have also been assessed. The lowest detectable dose were those of Riedel and Transia tests, 0.003 and 0.014 μg/l, respectively. The other tests also enable the detection of atrazine below 0.1 μg/l. All tests showed inter-assay coefficients of variation (C.V.) below 20%, the Transia, GEC-Marconi and Riedel tests producing the lowest inter-assay C.V.s. The mean intra-assay C.V.s were below 7% for all tests, the most homogeneous results being those of Transia and CIFEC. Except for the GEC-Marconi test which appeared very specific for atrazine, the most interfering triazines were terbutylazine, simazine and deethylatrazine. For the complete set of 41 water samples, the triazine concentrations measured by all the immunoassays and the sum of the triazines determined by gas chromatography-liquid chromatography were correlated at the 0.001 level, while for the water samples collected from lysimetric plates, the correlation coefficients were less significant, except for the Riedel test whose correlation coefficient remained significant at the 0.001 level. The laboratory-based assay from GEC-Marconi, still under development, showed promising characteristics with respect to sensitivity and specificity. The Riedel-de Haën test gave the best overall results.

Performance characteristics of a novel magnetic‐particlebased enzyme‐linked immunosorbent assay for the quantitative analysis of atrazine and related triazines in water samples

The performance characteristics of a magnetic‐particle‐based solid‐phase enzyme‐linked immunosorbent assay (ELISA) requiring no sample preparation for the quantification of atrazine and related triazines in groundwater samples is described. Water samples and HRP‐labeled atrazine are incubated with the antibody‐coupled solid phase for 15 min. A magnetic field is then applied to the solid phase to wash and remove free HRP‐labeled atrazine and to ensure the removal of potential interfering substances. After 20 min of color development using hydrogen peroxide/TMB, the reaction is stopped by the addition of acid. Photometric analysis of the final colored reaction was made using a specially designed microprocessor‐controlled photometer with extensive data reduction capability. The assay was found to be free of interferences when challenged with high concentrations of inorganic ions and a wide variation in sample pH. Sensitivity of the assay was 50 ppt based on 95% B/B0. Assay precision demonstrated coefficients...

HPLC determination of triazines in water samples in the ppt‐range by on‐column trace enrichment

HPLC determination of triazines in water samples in the ppt‐range by on‐column trace enrichment