Dyes In Water Samples Research Articles

Colorimetric and fluorometric sensing of polar E120 in juice and environmental water samples using mannitol-functionalized magnetic nanoparticles and nitrogen-doped carbon dots

In this study, mannitol-functionalized magnetic nanoparticles (MMNPs) as a unique nanosorbent and N-doped fluorescent carbon dots (N-CDs) as a cost-effective nanosensor were created and utilized, for the first time, for dispersive micro-solid-phase extraction (Dµ-SPE) to determine carmine (E120) dye in water samples and juices. The modification of the magnetic nanoparticles with mannitol was designed to enhance the responsive potential for adsorption of the polar E120 dye from complex sample matrices through electrostatic interaction. The as-fabricated N-CDs fluorescent probe exhibited a high fluorescence quantum yield (Φs) of 43.1 %, allowing for accurate fluorometric detection of E120 dye. The as-synthesized MMNPs nanosorbent and fluorescent N-CDs nanoprobe were characterized by Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Transmission electron microscopy (TEM), Energy Dispersive X-ray (EDX), Thermogravimetric analysis (TGA), and Vibrating-sample magnetometer (VSM). Density Functional Theory (DFT) studied the E120 dye structure using Gaussian 09 to explore the interactions between E 120 dye molecules and MMNPs/N-CDs. The impact of the critical adsorption and detection experimental factors was investigated and adjusted. A minimal amount of MMNPs nanosorbent (150 mg) is sufficient for E120 extraction in an acceptable time of 15 min. Furthermore, with a high determination coefficient, the adsorption characteristics fit with the models of Langmuir isotherm and first-order kinetics. The adsorption capacity (qe) of the as-fabricated MMNPs was 87.7 mg.g−1. After adsorption, E120 dye was fluorometrically analyzed using nitrogen-doped carbon dots as a fluorescent nanosensor via the inner filter effect (IFE) mechanism. Under the optimized conditions, the proposed fluorometric procedures showed a linear increase in the fluorescence ratio with increasing the E120 concentration in the range of 1.0 – 160.0 μg.mL−1 with detection (LOD) and quantitation (LOQ) limits of 0.27 and 0.83 μg.mL−1, respectively. The relative standard deviation (%RSD) did not exceed 2.34 %. The proposed methodology was successfully applied to determine E120 dye in juice and environmental water samples with % recovery ranged from 89.2-106.1 % and 92.9–107.2 %, respectively offering a reliable and environmentally friendly alternative to traditional detection methods with potential applications across various industries.

Tailoring of Novel Amorphous RuS2/ZrS2/MWCNT Nanocomposite Platform as a Dual Sensor for the Detection for Water Pollutant Indigo Carmine

The present study focuses on synthesizing amorphous nanocomposites of RuS2/ZrS2/MWCNT and exploring their potential for modifying electrodes and detecting indigo carmine dyestuff. Amorphous materials have recently garnered significant attention due to their ability to control material properties through their distinct nature. Transition metal dichalcogenides, or TMDs, are being extensively used in various applications such as catalysis, dye degradation, and so on. Amorphous transition metal sulphides, due to their heightened active sites, exhibit higher performance. This study presents the first-ever successful production of two amorphous metal sulphides that are doped with multi-walled carbon nanotubes. The resulting novel material was used to detect indigo carmine with high efficiency. The detection range was wide, spanning from 0.1 μM to 300.0 μM, and the limit of detection was 0.08 μM. These results demonstrate that the material outperforms most previously reported studies in this field. The technique employed was both simple and innovative, and it was used on both Glassy Carbon Electrode (GCE) and Screen-Printed Electrode (SPE) systems. It was effectively evaluated for the detection of the dye in water samples as well as food and pharmaceutical samples.

Dispersive micro-solid phase extraction coupled with spectrophotometric using (MgFe CLDH)/GO magnetically separable sorbent for pre-concentration of anionic food dyes in water samples

In the present study, a method was described for the extraction of Sunset Yellow (SY) and Tartrazine (TZ) as anionic food dyes in actual samples by using magnetic calcined layered double hydroxide onto graphene oxide (MgFe CLDH)/GO (called MgO/MgFe2O4/GO) sorbent. The analytes were accumulated on MgO/MgFe2O4/GO-NCs with more detail recognized by XRD, FESEM, EDS element mapping, VSM and FTIR methods. The prepared nanocomposite (NC) was employed as an extractive phase for dispersive micro-solid phase extraction (D-μ-SPE) of SY and TA from actual samples. Then, the extracted SY and TZ dyes were analyzed by UV–vis spectrophotometer. Main variables related to the extraction process including pH, nano composite mass, sonication and vortex time and eluent volume were optimized by central composite design (CCD). The optimum conditions obtained for pH, nano composite mass, sonication and vortex time and eluent volume were 6.0, 0.02 g, 16 s and 6.40 min, and 500 μL, respectively. The extraction recovery equal to 96.31 % and 97.66 % for SY and TZ, respectively obtained from the predicted model, was in agreement with the experimental data (95.32 ± 2.33 % and 96.89 ± 1.84 %). In addition, under the optimal conditions, the calibration curve was found out to be linear over the concentration range of 0.5–2.50 mg L−1 with R2 > 0.98. The LODs ranged from 0.14 to 0.16 mgL−1. Furthermore, the enrichment factors (EF) were achieved in the range of 20.65–36.66 with pre-concentration factor (PF) of 20. In the meantime, the obtained assay accuracy in the analysis of medical extract of Miranda Drink, Saffron and water samples fell within the range of 93.00%–107.00 %, whilst the precision expressed RSD lower than 3.50 %.

Removal and measurement of trace amounts of rhodamine B in aqueous samples based on the synthesis of a nanosorbent composed of Fe3O4 nanoparticles modified with SiO2 and polydopamine by magnetic solid phase extraction.

Rhodamine B (RDB) dye is generally toxic and causes problems such as carcinogenic activities, neurological disorders, and respiratory tract irritations. However, some individuals still illegally use RDB as a food additive. Therefore, a simple and accurate method is needed to determine RDB in real samples such as food or cosmetic products. In this study, the magnetic solid phase extraction (MSPE) method was used to measure very low amounts of RDB dye in water samples. The advantages of this method include simplicity, good repeatability, high preconcentration factor, higher extraction efficiency, low organic solvent volume requirement, rapid separation, low cost, high sensitivity, and interference removal compared to other methods. Within this approach, iron oxide nanoparticles were synthesised, followed by the application of tetra ethoxy silane (TEOS) and polydopamine (PDA) coatings on the nanoparticle surface, resulting in the creation of the Fe3O4@SiO2@PDA nano-sorbent. This nano-sorbent was then utilized as the magnetic solid phase in MSPE. The characteristics of the synthesized compounds were investigated by various methods such as infrared Fourier transform spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction spectroscopy (XRD), and vibrating sample magnetometry (VSM). Response surface methodology (RSM) and Box-Behnken (BB) design were used to optimize the variables affecting the adsorption process and achieved high recovery percentages. Under optimal experimental conditions, the detection limit and quantification limit of the method were found to be 0.73 and 2.42 μg L-1 for RDB, respectively, with RSDs of ±0.32% and ±0.67%. Furthermore, the linear concentration range of the proposed method for solid phase extraction of RDB was determined to be 10.0-900.0 μg L-1. Moreover, the recovery rates for tap water, lake water, and well water samples ranged from 96.9% to 98.6%.

Fabrication of a novel dual-emission fluorescence covalent organic framework and its luminescent hybrid hydrogel material: Application in the detection and adsorption of eriochrome azo anionic dyes

Herein, a novel fluorescent covalent organic framework (COF) and its luminescent sodium alginate based hybrid hydrogel were synthesized and applied to detect and adsorb eriochrome azo anionic dyes. Firstly, by optimizing a series of conditions affecting the crystallinity, a dual-emission fluorescence COF (TD-COF) with high crystallinity was synthesized at room temperature for the first time. TD-COF yielded remarkable fluorescence and adsorption properties; thus it can be employed as a dual platform for fluorescence sensing and adsorption of eriochrome black T, eriochrome blue-black R and eriochrome blue SE. The platform showed good linearity in fluorescence detection of three dyes from 0 to 100 μg mL−1 and the maximum adsorption capacities ranged from 89.28 to 228.64 mg g−1. Subsequently, TD-COF had a Thiol-ene "click" reaction with thiolated sodium alginate to produce a sort of luminescent hybrid hydrogel material (GelTSA@TD-COF), which improved the maximum adsorption capacities of eriochrome blue-black R (6410.06 mg g−1) and eriochrome blue SE (106.79 mg g−1). Due to the blocky appearance of GelTSA@TD-COF, it is more portable and practical compared to powdered TD-COF, and can be used for on-site fluorescent visualization of dyes. Finally, the detection and adsorption effect of dyes in water samples further verified the practical application value of TD-COF and GelTSA@TD-COF.

Ultrasound-assisted dispersive solid-phase extraction for the preconcentration of dyes in water samples

In this research, the magnesium ferrite/zinc oxide (MgFe2O4/ZnO) nanocomposite has been utilized as an effective adsorbent in the ultrasound-assisted dispersive solid-phase extraction (USA-DSPE) coupled to a spectrophotometric method for preconcentration of methylene blue (MB) and safranin O (SO) dyes. X-Ray diffraction (XRD), vibrating sample magnetometer (VSM), transmission electron microscopy (TEM), and field emission scanning electron microscopy (FESEM) analyses were performed to characterize and confirm the properties of the synthesized MgFe2O4/ZnO nanocomposite. Box-Behnken design (BBD) based on response surface methodology (RSM) was utilized to optimize the variables. The results of this research showed that the maximum extraction efficiency was obtained at pH = 7, eluent volume of 140 µL, adsorbent amount of 1.53 mg, and ultrasonic time of 8 min. After optimization by RSM and using the Quadratic model, the extraction efficiency for MB and SO was 98.60% and 97.23%, respectively. The analysis of variance (ANOVA) showed that the data obtained from the experiment were consistent with the predicted model. Under optimal conditions, the calibration curve was linear in the range of 5–1000 µg/L (coefficient of determination of 0.9884) for MB and 10–1100 µg/L (coefficient of determination of 0.9973) for SO. The limit of detections (LOD) of the proposed method for MB and SO were determined as 1.5 µg/L and 3 µg/L, respectively. The relative standard deviations (RSD, n = 5) for MB and SO were obtained as 1.1% and 2.1%, respectively. The results of adsorbent recovery revealed that MgFe2O4/ZnO nanocomposite could be used several times without a significant adsorbent efficiency loss. Furthermore, the findings of interference studies revealed that the presence of different ions does not cause substantial interference with the extraction of dyes. The environmental water samples analysis showed that the extraction efficiency for dyes was in the range of 93.74–99.11%.

Separation and Preconcentration of Anionic Dyes Using Magnetic Nanoparticles with Modify Polymer Ionic Liquid

In this study, functionalized magnetic nanoparticles of poly (ionic liquid) 1-allyl-3-methylimidazolium chloride were prepared through free radical copolymerization method and tested as a high efficient adsorbent for the removal of anionic dyes in water samples. The physical and chemical structure of prepared magnetic nanoparticles (MNPs) were investigated using Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Next, synthesized magnetic nanoparticles were used in magnetic solid phase extraction (MSPE) method to extract three anionic dyes (Alizarin Red S, Congo Red and Methyl Orange) in water samples. Also, the effect of several parameters such as pH, temperature, contact time and amount of adsorbent was investigated and the optimum values were determined. In addition, the adsorbent has a high ability to remove anionic dyes from water samples containing different dyes. Limit of detection (LOD), limit of quantitation (LOQ), and correlation coefficient were determined for methyl orange, Congo red and alizarin red S dyes under optimum conditions. The synthesized magnetic nanoparticles can be collected by an external magnetic field and regenerated with an alkaline solution (NaOH) and reused. The obtained results showed that the MNPs@PIL method was very efficient and successful in removing dye pollutants in water samples.

Cloud Point Extraction for Spectrophotometric Determination of Acid Blue 29 Dye in Water Samples

A simple and fast Cloud Point Extraction (CPE) preconcentration of Acid Blue 29 (AB 29) dye was developed prior to its spectrophotometric determination. The suggested procedure was successfully applied for the determination of AB 29 dye in different water samples with high recoveries. Optimization of experimental conditions such as surfactant type and volume, pH, stirring, and centrifugation conditions were studied. The effect of interfering ions was also studied. The calibration curve was in the range of 0.4-10 µgmL-1 with a limit of detection and limit of quantitation of 0.35 and 1.1 µgmL-1, respectively. Furthermore, the method is free of the interference of common ions present in water.

Quantification of twenty pharmacologically active dyes in water samples using UPLC-MS/MS

This study presents a multi-compound method for the determination of 20 pharmacologically active dyes from 5 different chemical classes in environmental water samples. These compounds, including triphenylmethane dyes (malachite green, crystal violet, brilliant green, ethyl violet, methyl violet 2B, pararosaniline, victoria blue B, victoria blue R, victoria pure blue BO), phenothiazine dyes (methylene blue, azure A, azure B, azure C, new methylene blue, thionine), phenoxazine dye (nile blue A), acridine dyes (acriflavine, proflavine) and xanthene dyes (rhodamine B, rhodamine 6G) constitute pharmacologically active substances (PASs). For the optimisation of sample preparation, different solid-phase extraction (SPE) sorbents and a wide range of pH (from 2 to 12) of water samples were tested. Finally, water samples were preconcentrated and cleaned up on diol SPE cartridges. Extracts were analysed by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) operating in the positive electrospray ionisation (ESI+) mode. The chromatographic separation of the 20 pharmacologically active dyes was achieved within 5 min by using a pentafluorophenyl (F5) analytical column and mobile phases of ammonium acetate buffer (0.05 M, pH = 3.5) and acetonitrile with gradient elution. The developed method was validated proving to be suitable for the determination of all tested compounds. Limits of quantification were 0.01–0.1 μg/l, are sensitive enough to quantify very low concentration levels of the dyes in environmental water samples. The obtained recovery values for all tested analytes were between 71.2 and 104.9% with a good RSD, less than 14 % at all fortification levels. The application of the developed method to water samples allows the detection of dyes such as crystal violet, rhodamine B, and methyl violet in two wastewater samples in concentration range from 0.017 to 0.0043 μg/l).

New fabrication of CuFe2O4/PAMAM nanocomposites by an efficient removal performance for organic dyes: Kinetic study.

Today, removing pollutants from water sources is essential because of the population increase and the growing need for safe drinking water. Dyes are one of the most critical pollutants from industrial effluents such as paper and textile industries that profoundly affect the environment. There are several ways to remove environmental contaminants. Magnetic nanoparticles have a high ability to adsorb dyes. Of course, increasing the interaction between magnetic nanomaterials and pollutants is also essential, which can be done using porous materials such as dendrimers. In this work, the synthesis of CuFe2O4 magnetite nanoparticles within the polyamidoamine dendrimers structure was used as an efficient sorbent to remove both alizarin reds (ARS) and brilliant green (BG) dyes. Moreover, various parameters for dyes removal were studied. The optimum removal conditions were obtained for ARS within 30min at a sorbent dose of 2mg per 5mL for the initial dye concentration of 7.0ppm in pH 6at 25°C, and for BG within 45min at a sorbent dose of 5mg per 5mL for the initial dye concentration of 17.0ppm in pH 8at 25°C. At the optimum values of the above parameters, both dyes' removal efficiency was more than 97%. Also, the obtained results showed that the adsorption isotherm follows the Langmuir model and Temkin model for ARS and BG, respectively. This method was successfully used for the removal of both dyes in water samples.

Analysis of Time-Resolved Plasma Jet Emissions That Drive Methylene Blue Dye Decomposition

Plasma-based water purification uses energetic electrons to induce chemical reactions that break down harmful contaminants into benign components. The chemical reactions needed to decompose organic chemicals and bacteria in water are driven by the production of the hydroxyl radical, OH. In this article, an atmospheric pressure plasma jet was used to produce OH and decompose methylene blue (MB) dye in water samples. The behavior of the plasma and the emission of excited OH* near the plasma-liquid interface were analyzed. Nanosecond-resolved measurements near the plasma-water interface were obtained using ICCD imaging and emissions spectroscopy synchronized to the pulsed dc power that drives plasma formation in the plasma jet. The plasma was observed to form along the front of ionization waves as “bullets” that locally produce reactive species. When the bullet hits the water surface, it rebounds and creates a secondary excitation of species at the water surface. The bouncing phenomenon increases the plasma interactions above the water surface and increases OH* excitation up to 192%. However, this increase in excitation and emission does not necessarily mean increased total OH. Higher discharge frequencies produced more OH* emission but did not change the rate of MB dye removal. Higher voltages do increase dye removal rate but with decreasing effectiveness. The results indicate that in steady state, most of the water in the gas channel has been dissociated to form OH, and each bullet merely re-excites the ground state OH (X) into OH* (A) state. A minimum operational frequency of 1 kHz was thus found to provide the best efficiency while maintaining OH production.

Synchronous Construction of Hierarchical Porosity and Thiol Functionalization in COFs for Selective Extraction of Cationic Dyes in Water Samples.

Pore size and functionalization are two critical factors for covalent organic frameworks (COFs) as effective adsorbents. However, due to the low crystallinity of COFs, it is a grand challenge to accomplish pore diameter adjustment and functionalization at the same time. In this work, we developed a simple and ingenious strategy, cutting off linkage, to synchronously construct hierarchical porosity and modify thiol groups in COFs under mild conditions. The hybrid COFs containing disulfide bonds were designed and synthesized, and then the disulfide bonds were cleaved by glutathione, resulting in the formation of thiol groups as well as the increase in pore size caused by skeleton defects. The pore diameter of thiol-functionalized hierarchical porous COFs (denoted as HP-TpEDA-SH) was concentrated at 2.6 and 3.5 nm. Thanks to the electrostatic attraction of thiol groups to cationic dyes and the higher number of available adsorption sites, the maximum extraction amounts of methylene blue (MB), malachite green (MG), and crystal violet (CV) by HP-TpEDA-SH were 2.6, 2.1, and 3.3 times those of microporous COFs under optimal extraction conditions, respectively. The proposed analytical method (solid-phase extraction-high-performance liquid chromatography/ultraviolet (SPE-HPLC/UV)) with HP-TpEDA-SH as the adsorbent showed low detection limits of 1.3, 0.13, and 0.12 μg·L-1 for MB, MG, and CV, respectively. The recoveries of three spiked water samples ranged from 81.5 to 113.8%, with relative standard deviations (RSDs) less than 9.7%. This work not only opened a new avenue for the preparation of functionalized hierarchical porous COFs but also established an effective method for detecting trace cationic dyes in fishery water.

Sustainable fabrication, optical properties and rapid performance of bio-engineered copper nanoparticles in removal of toxic methylene blue dye in an aqueous medium

Copper nanoparticles have obtained due to the green process in a one-pot reaction at ambient temperature using Malva Sylvesteris leaves extract. The plant extract has used as a reducing and capping agent, providing stability and avoiding oxidation of synthesized copper nanoparticles for more than eight months. Many techniques have exploited for the investigation of optical and physicochemical properties of copper nanoparticles. UV-VIS spectroscopy showed two bands at different locations for the extract and nanoparticles at 340 and 390 ​nm, respectively. Fourier transform infrared spectroscopy confirmed the role of bioactive materials in the plant extract as a reducing and capping agent. X-ray diffraction tool affirmed the crystalline nature of fabricated copper nanoparticles at average (20 ​nm) and showed a centred cubic structure. Field emission scanning electron microscope (FESEM) chart illustrated the roughly spherical shape of distributed copper nanoparticles. The copper nanoparticles showed high-efficiency removal of methylene blue dye in water samples.

Flower-like layered double hydroxide-modified stainless-steel fibers for online in-tube solid-phase microextraction of Sudan dyes.

Layered double hydroxides are a family of inorganic crystals that have gained a lot of attention due to its special structure and properties such as high porosity, large specific area, and excellent anion exchange ability. In this work, flower-like NiAl-layered double hydroxides with high specific area were in situ immobilized onto the stainless steel fibers by bioinspired polydopamine modification method and packed into poly (ether ether) ketone tube for online solid-phase microextraction with high performance liquid chromatography analysis. Thanks to the high specific surface area and excellent extraction ability of the NiAl-layered double hydroxides, the fibers showed excellent extraction performance to three Sudan dyes with enrichment factors between 260 to 650 folds. After optimization of the reaction and extraction conditions, an online solid-phase microextraction method was developed for determination of Sudan dyes in water samples and chili samples. The method has limits of detection of 0.01 to 0.02ng/mL, good linearity and good reproducibility (≤1.45%).

Determination of Sudan red contaminants at trace level from water samples by magnetic solid-phase extraction using Fe@NiAl-layered double hydroxide coupled with HPLC

BackgroundSudan red dyes are widely used as color additions in various fields. Due to their potential carcinogenicity and large consumption, they have absorbed much more attention and become a research hot topic. There have been a few of existing methods for their analysis from samples; however, it is of great importance to develop simple, sensitive, and low-cost analytical method for public health and safety. This article described a new method based on magnetic Fe@NiAl-layered double hydroxides for enrichment of Sudan red dyes in combination with high-performance liquid chromatography.ResultsThe as-prepared magnetic Fe@NiAl-layered double hydroxides (Fe@NiAl-LDHs) exhibited good adsorption capacity for Sudan red dyes, and could be used as an effective adsorbent for preconcentration of three Sudan Red dyes from environmental water samples. The proposed method provided low limits of detection in the range of 0.002–0.005 μg L−1 with magnetic solid-phase extraction in combination with high-performance liquid chromatography.ConclusionThe developed method utilized the easy to prepare magnetic materials as adsorbents and conventional analytical instrument and provided high sensitivity, which provided a robust and low consumption of toxic organic solvent alternative method. The results of present study are of great value for interested laboratories to monitor the level of Sudan red dyes in water samples or develop sensitive determination methods to monitor other pollutants at trace level in environmental waters.

Large‐volume sample stacking with polarity switching for analysis of azo dyes in water samples by capillary electrophoresis

ABSTRACTA simple, fast and efficient on-line pre-concentration method (large-volume sample stacking) by capillary electrophoresis was proposed for determination of azo dyes residues (allura red [AR], sunset yellow [SY] and tartrazine [TAR]) in water samples. Pre-concentration variables involved in the system were optimised using of a Box–Bhenken design. Under the optimal conditions: injection time 150.0 s, pre-concentration time 120.0 s and reverse potential −8.0 kV, the proposed methodology improved the analytical sensibility achieving limits of detection of 21.0–41.4 µg L−1 with enrichment factors of 82.1–210.8 fold. The large-volume sample stacking-capillary electrophoresis method was validated and applied to determine azo dyes residues in 20 water samples (bottled, spring and tap water). Two samples were positive for sunset yellow and tartrazine with a concentration of 25.3 and 30.2 µg L−1 and % RSD less than 10.0% in all cases.

Stir bar sorptive extraction with a graphene oxide framework-functionalized stainless-steel wire for the determination of Sudan dyes in water samples

A graphene oxide framework-modified stainless-steel wire was developed for stir bar sorptive extraction.

Comparison between dispersive solid-phase and dispersive liquid–liquid microextraction combined with spectrophotometric determination of malachite green in water samples based on ultrasound-assisted and preconcentration under multi-variable experimental design optimization

The ultrasound-assisted dispersive solid-phase microextraction (USA-DSPME) and the ultrasound-assisted dispersive liquid–liquid microextraction (USA-DLLME) developed for as an ultra preconcentration and/or technique for the determination of malachite green (MG) in water samples. Central composite design based on analysis of variance and desirability function guide finding best operational conditions and represent dependency of response to variables viz. volume of extraction, eluent and disperser solvent, pH, adsorbent mass and ultrasonication time has significant influence on methods efficiency. Optimum conditions was set for USA-DSPME as: 1mg CNTs/Zn:ZnO@Ni2P-NCs; 4min sonication time and 130μL eluent at pH 6.0. Meanwhile optimum point for USA-DLLME conditions were fixed at pH 6.0; 4min sonication time and 130, 650μL and 10mL of extraction solvent (CHCl3), disperser solvent (ethanol) and sample volume, respectively. Under the above specified best operational conditions, the enrichment factors for the USA-DSPME and USA-DLLME were 88.89 and 147.30, respectively. The methods has linear response in the range of 20.0 to 4000.0ngmL−1 with the correlation coefficients (r) between 0.9980 to 0.9995, while its reasonable detection limits viz. 1.386 to 2.348ngmL−1 and good relative standard deviations varied from 1.1% to 2.8% (n=10) candidate this method for successful monitoring of analyte from various media. The relative recoveries of the MG dye from water samples at spiking level of 500ngmL−1 were in the range between 94.50% and 98.86%. The proposed methods has been successfully applied to the analysis of the MG dye in water samples, and a satisfactory result was obtained.

Synthesis and evaluation of a molecularly imprinted polymer for selective adsorption and quantification of Acid Green 16 textile dye in water samples

An alternative for determining environmental pollutants, like textile dyes, is the use of molecularly imprinted polymers (MIPs) as solid phase extraction (SPE) or as sensor recognition systems. MIPs are tailor-made artificial receptor sites in a polymer, which present good affinity and selectivity. This work shows the synthesis of MIPs for the Acid Green 16 (AG16) textile dye and the results of rebinding, selectivity and application of this MIP in water samples. MIP synthesis was performed using AG16 dye (template), 1-vinylimidazole (functional monomer), ethylene-glycol-dimethacrylate (cross-link), 2,2′-azobis(2-methylpropionitrile) (initiator) and methanol (solvent) by bulk synthesis. The imprinted polymer presented excellent rebinding of 83%, an imprinted factor of 6.91 and great selectivity in comparison with other textile dyes. Additionally, the MIP showed high efficiency in the extraction of this dye in water samples, presenting a recovery rate close to 100% and a better performance when compared to commercial SPE cartridges. Due to this excellent performance for AG16, the application of this MIP to determine dyes in different matrices of environmental importance is promising.

Efficient method for determination of methylene blue dye in water samples based on a combined dispersive solid phase and cloud point extraction using Cu(OH)2 nanoflakes: central composite design optimization.

A new method was developed for the efficient spectrophotometric determination of methylene blue (MB) dye in solutions. The method is based on a combined dispersive solid phase and cloud point extraction using Cu(OH)2 nanoflakes (as an adsorbent). Cu(OH)2 nanoflakes were synthesized by facile and fast methods and characterized using various techniques. The developed method is based on the adsorption of MB on the Cu(OH)2 nanoflakes and transfer into a surfactant-rich phase using Triton X-114 as a nonionic surfactant. Subsequently, MB dye is desorbed from Cu(OH)2 nanoflakes using a mixture of nitric acid and methanol solution and determined by UV-Vis spectrophotometry. The effects of pH, amount of Cu(OH)2 nanoflakes, volume (concentration of Triton X-114), and temperature were investigated by designing experiments using response surface methodology (RSM). A quadratic model was utilized to predict the variables. Analysis of variance (ANOVA) was applied for the analysis of variables and their interactions, and optimal conditions were established. The results demonstrated logical agreement between experimental and predicted values of the response owing to high F value, low P value, and low lack-of-fit. The calibration graph was linear in the range of 2.0-350.0μgL-1 of MB dye with a correlation coefficient (R) of 0.9996. The limits of detection and quantification were found to be 0.65 and 2.05μgL-1, respectively. The developed method was successfully applied to different water samples, thereby confirming the applicability of the approach. Graphical Abstract Proposed procedure.