Surfactant modified coconut husk fiber as a green alternative sorbent for micro-solid phase extraction of triazole fungicides at trace level in environmental water, soybean milk, fruit juice and alcoholic beverage samples.

In this work, micro-solid phase extraction using surfactant modified biosorbent was investigated for trace level determination of triazole fungicides prior to their analysis by high performance liquid chromatography. Coconut husk fiber (CHF) was selected as an effective biosorbent in the extraction process. Fourier transform infrared spectrometry, scanning electron microscopy and transmission electron microscopy methods were used to characterize the modified biosorbent. Various factors affecting the extraction efficiency of the proposed method were studied including the amount of coconut husk fiber biosorbent (0.1 g), kind and concentration of surfactant as a modifier (sodium dodecyl sulfate, 10 mmol L-1), kind and volume of desorption solvent (methanol, 150 µL), and extraction period (including vortex adsorption time, centrifugation adsorption time, vortex desorption time and centrifugation adsorption time approximately 10 min). Under the selected conditions, the calibration plot was found to be linear in the range of 9-300 µg L-1 with a coefficient for determination of greater than 0.99. The limits of detection and limits of quantification for the studied triazole fungicides were 3.00 and 9.00 µg L-1, respectively. Finally, the proposed method was successfully applied to determine triazole fungicides in environmental water, soybean milk, fruit juice and alcoholic beverage samples with acceptable recoveries obtained in the range of 67.0% to 105.0%.

Preconcentration of Heterocyclic Aromatic Amines in Edible Fried Insects Using Surfactant-Assisted Hydrophobic Deep Eutectic Solvent for Homogeneous Liquid-Liquid Microextraction prior to HPLC.

Thermal processing techniques are often accompanied by the production of many harmful compounds such as heterocyclic aromatic amines (HAAs). To protect human health, an efficient and environmentally friendly method, namely, homogeneous liquid-liquid microextraction (HLLME), was investigated. This method is based on a surfactant-assisted hydrophobic deep eutectic solvent for the determination of HAAs in edible fried insect samples prior to their analysis by high-performance liquid chromatography coupled with UV detection. A hydrophobic deep eutectic solvent (as extraction solvent) was synthesized using decanoic acid as a hydrogen bond donor and tetrabutylammonium bromide (TBABr) as a hydrogen bond acceptor and then characterized by Fourier transform infrared (FTIR) spectroscopy. The surfactant was used as the emulsifier and induces mass transfer, resulting in an increasing extraction efficiency of the proposed method. Various factors affecting the extraction performance were investigated and optimized. A matrix-match calibration method was used to analyze HAAs in high heat-treated edible fried insect samples. Under optimized conditions, the proposed method showed good linearity (R2 ≥ 0.99) with satisfactory limits of detection and satisfactory reproducibility with relative standard deviation of less than 10.0%. Furthermore, the procedure greenness was assessed using the Analytical Eco-Scale. This paper represents the first application of HLLME based on a surfactant-assisted hydrophobic deep eutectic solvent to analyze HAAs in edible fried insect samples.

Trace-Level Determination of Triazole Fungicides Using Effervescence-Assisted Liquid-Liquid Microextraction Based on Ternary Deep Eutectic Solvent Prior to High-Performance Liquid Chromatography.

A simple and sensitive preconcentration method, namely, effervescence-assisted liquid-liquid microextraction based on the ternary deep eutectic solvent method, was developed for enrichment of triazole fungicide residues prior to their determination by high-performance liquid chromatography coupled with UV detection. In this method, a ternary deep eutectic solvent (as extractant) was prepared by combination of octanoic acid, decanoic acid, and dodecanoic acid. The solution was well dispersed with sodium bicarbonate (as effervescence powder) without using auxiliary devices. In order to obtain relatively high extraction efficiency, analytical parameters were investigated and optimized. Under optimum conditions, the proposed method showed good linearity within the range of 1-1000 µg L-1 with a coefficient for determination (R2) greater than 0.997. The low limits of detection (LODs) were in the range of 0.3-1.0 µg L-1. The precisions were assessed from the relative standard deviations (RSDs) of retention time and peak area obtained from intra- (n = 3) and inter-day (n = 5 × 5) experiments, which were greater than 1.21 and 4.79%, respectively. Moreover, the proposed method provided high enrichment factors ranging from 112 to 142 folds. A matrix-match calibration method was used for analysis of real samples. Finally, the developed method was successfully applied for determination of the triazole fungicide in environmental water (near agricultural area), honey, and bean samples, and it represents a promising alternative method for analysis of triazoles. The recoveries of the studied triazoles were obtained in the range of 82-106% with an RSD less than 4.89.

Efficient analyses of triazole fungicides in water, honey and soy milk samples by popping candy-generated CO2 and sugaring-out-assisted supramolecular solvent-based microextraction prior to HPLC determinations.

An enrichment method, namely popping candy-generated CO2 and sugaring-out-assisted supramolecular solvent-based microextraction (PGS-SUPRA), was investigated for the determination of triazole fungicide residues in water, honey and soy milk samples. The extraction process was carried out by adding popping candies into a centrifuge tube. Consequently, rapid dispersion and mass transfer of extractants can be achieved without using dispersants and auxiliary devices, and therefore, the extraction efficiency increased. The extraction parameters affecting the efficiency of the developed method were investigated. The presented method was then analysed by high-performance liquid chromatography. Under the selected condition, the wide linearity of triazole fungicides after preconcentration by the proposed microextraction method ranged from 30 to 1000 µg L-1 for triadimefon and from 90 to 1000 µg L-1 for myclobutanil, tebuconazole and hexaconazole, with a coefficient for determination (R 2) greater than 0.992. The limits of detection (LODs) and limits of quantitation (LOQs) were in the range of 10-30 µg L-1 and 30-90 µg L-1, respectively. The precisions were assessed from the relative standard deviations (RSDs) of the retention time and peak area obtained from intra- (n = 3) and inter-day (n = 3 × 5) experiments, and were greater than 1.66% and 13.52%, respectively. Moreover, the proposed method provided high enhancement factors (EnFs) ranging from 14 to 51 folds. This technique has been prosperously applied for the extraction of fungicide residues in water, honey and soy milk samples with a recovery within the range of 60-114%. Overall, the developed method was found to be advantageous as compared with other sample preparation methods.

Modified Peanut Shell as an Eco-Friendly Biosorbent for Effective Extraction of Triazole Fungicide Residues in Surface Water and Honey Samples before Their Determination by High-Performance Liquid Chromatography.

An eco-friendly sample preparation method that is based on the use of a modified peanut shell as an efficient biosorbent for the extraction of triazole residues before their analysis by high-performance liquid chromatography was reported. The four triazole fungicides were separated on a Purospher STAR RP-18 endcapped (4.6 × 150 mm, 5 µm) column with a mobile phase of 50% (v/v) acetonitrile at a flow rate of 1.0 mL min-1 and detection wavelength set at 220 nm. Peanut shells modified by didodecyldimethylammonium bromide were selected as an effective biosorbent material in the microextraction method. Scanning electron microscopy, transmission electron microscopy, and Fourier transform infrared spectroscopy were used to characterize the biosorbent. The effect of dominant parameters on the proposed microextraction method including the amount of sorbent, kind and concentration of surfactant, sodium hydroxide concentration, kind and amount of salt, sample volume, adsorption time, kind and volume desorption solvent, and desorption time was studied. Under the optimum condition, a good analytical performance for the proposed microextraction method was obtained with a wide linear range within the range of 9-1000 µg L-1, and low limits of detection (0.03 µg L-1 for all analytes) were obtained. Enrichment factors were achieved within the range of 30-51. The intra and interday precision values were evaluated in terms of percentage relative standard deviations (%RSD) and were less than 0.09 and 5.34% for the retention time and peak area, respectively. The proposed microextraction methods were used for extraction and analysis of triazole fungicides in water and honey samples. The recoveries in a satisfactory range of 70.0-118.8% were obtained.

Simultaneous Preconcentration of Triazole Fungicide Residues Using In-Situ Coacervative Extraction Based on a Double-Solvent Supramolecular System Prior to High Performance Liquid Chromatographic Analysis.

An in situ coacervative extraction (IS-CAE) based on a double-solvent supramolecular system coupled to liquid-liquid microextraction is investigated for extraction and enrichment of triazole fungicides. The formation of a double-solvent supramolecular system was generated by in situ formation and used as an extraction solvent for the coacervative extraction method. No disperser solvent was required. This new double-solvent supramolecular system has a higher extraction ability than any of its components alone. The different factors that could affect the extraction capability were studied and optimized, including the type of double extractant and its volume, salt addition, vortex time, and centrifugation time. Under optimum extraction conditions, this method provides high enrichment factors (EFs) of 73-318 with low limits of detection (LODs) of 0.3-1 µg L-1 and limits of quantitation (LOQs) of 1-3 µg L-1. In addition, the proposed method was prosperously applied for the determination of triazole fungicides in water, fruit juice, and soy milk samples.

An In Situ Formation of Ionic Liquid for Enrichment of Triazole Fungicides in Food Applications Followed by HPLC Determination.

An in situ formation of ionic liquid was used for preconcentration of four triazole fungicides in food samples. The microextraction method was used for the first time in the literature for preconcentration of triazole fungicides. In the developed method, tributylhexadecylphosphonium bromide ([P44412]Br) and potassium hexafluorophosphate (KPF6) were used for the formation of hydrophobic ionic liquid. After centrifugation, the fine microdroplets were produced in one step, providing the extraction step in a quick and environmentally friendly manner. The functional group of the hydrophobic ionic liquid was investigated using FT-IR. Various extraction parameters were studied and optimized. In the extraction method, 0.01 g of [P44412]Br and 0.01 g of KPF6, centrifugation at 4500 rpm for 10 min were used. The optimized technique provided a good linear range (90-1000 µg L-1) and high extraction recovery, with a low limit of detection (30-50 µg L-1). Methods for the proposed in situ formation of ionic liquid were successfully applied to honey, fruit juice, and egg matrices. The recoveries were obtained in a satisfactory range of 62-112%. The results confirmed the suitability of the proposed microextraction method for selective extraction and quantification of triazole fungicides.

In-Situ Formation of Modified Nickel-Zinc-Layered Double Hydroxide Followed by HPLC Determination of Neonicotinoid Insecticide Residues.

A single-step preconcentration procedure using the in-situ formation of modified nickel-zinc-layered double hydroxides (LDHs) prior to high-performance liquid chromatography (HPLC) is investigated for the determination of neonicotinoid insecticide residues in honey samples. The LDHs could be prepared by the sequential addition of sodium hydroxide, sodium dodecyl sulfate, nickel nitrate 6-hydrate and zinc nitrate 6-hydrate, which were added to the sample solution. The co-precipitate phase and phase separation were obtained by centrifugation, and then the precipitate phase was dissolved in formic acid (concentrate) prior to HPLC analysis. Various analytical parameters affecting extraction efficiency were studied, and the characterization of the LDHs phase was performed using Fourier-transformed infrared spectroscopy and scanning electron microscopy. Under optimum conditions, the limit of detection of the studied neonicotinoids, in real samples, were 30 µg L-1, for all analytes, lower than the maximum residue limits established by the European Union (EU). The developed method provided high enrichment, by a factor of 35. The proposed method was utilized to determine the target insecticides in honey samples, and acceptable recoveries were obtained.

An Eco-Friendly Hydrophobic Deep Eutectic Solvent-Based Dispersive Liquid-Liquid Microextraction for the Determination of Neonicotinoid Insecticide Residues in Water, Soil and Egg Yolk Samples.

A green, simple and sensitive hydrophobic DES-based dispersive liquid-liquid microextraction coupled with high-performance liquid chromatography (HPLC) was developed for the analysis of neonicotinoid insecticide residues in various samples. A hydrophobic deep eutectic solvent (DES) was synthesized using decanoic acid as a hydrogen bond donor and tetrabutylammonium bromide (TBABr) as a hydrogen bond-acceptor. DESs were synthesized and characterized by Fourier transform-infrared (FTIR) spectroscopy. Two disperser solvents were substituted with surfactants and acetonitrile, which could afford more effective emulsification and make the extraction relatively greener. The hydrophobic DES extraction phase occurred 10 min after centrifugation, being easy to be collected for analysis. Several parameters were investigated and optimized. Under the optimum condition, the calibration curve of this method was linear in the range of 0.003-1.0-µg·mL-1, with a correlation coefficient (R2) higher than 0.99 and a good repeatability, with the relative standard deviations (RSDs) were less than 5.00%. The limits of detection were in the range of 0.001-0.003 µg·mL-1; the limits of quantitation were in the range of 0.003-0.009 µg·mL·mL-1. Finally, the presented method was implemented to determine the neonicotinoid insecticide residues in water, soil, egg yolk samples and acceptable recoveries were obtained.

ß-Cyclodextrin Assisted Liquid-Liquid Microextraction Based on Solidification of the Floating Organic Droplets Method for Determination of Neonicotinoid Residues.

An efficient and environment-friendly microextraction method, namely, ß-cyclodextrin assisted liquid-liquid microextraction, based on solidification of the floating organic droplets method coupled with HPLC is investigated for the sensitive determination of trace neonicotinoid pesticide residues. In this method, ß-cyclodextrin is used as a disperser solvent, while 1-octanol is selected as an extraction solvent. ß-cyclodextrins was found to decrease interfacial tension and increase the contact area between the organic and water phases with the help of centrifugation. A cloudy solution was rapidly formed and then centrifuged to complete phase separation. Various key parameters influencing extraction efficiency were systematically investigated and optimized; they include salt addition, concentration of ß-cyclodextrin, and volume of extraction solvent (1-octanol). Under optimum conditions, good linearity was obtained with coefficient for determination (R2) greater than 0.99. A low limit of detection, high enrichment factor, and good recovery (83 - 132) were achieved. This proves that the proposed method can be applied to determine trace neonicotinoid pesticide residues in natural surface water samples.

Ultrasonically Modified Amended-Cloud Point Extraction for Simultaneous Pre-Concentration of Neonicotinoid Insecticide Residues.

An effective pre-concentration method, namely amended-cloud point extraction (CPE), has been developed for the extraction and pre-concentration of neonicotinoid insecticide residues. The studied analytes including clothianidin, imidacloprid, acetamiprid, thiamethoxam and thiacloprid were chosen as a model compound. The amended-CPE procedure included two cloud point processes. Triton™ X-114 was used to extract neonicotinoid residues into the surfactant-rich phase and then the analytes were transferred into an alkaline solution with the help of ultrasound energy. The extracts were then analyzed by high-performance liquid chromatography (HPLC) coupled with a monolithic column. Several factors influencing the extraction efficiency were studied such as kind and concentration of surfactant, type and content of salts, kind and concentration of back extraction agent, and incubation temperature and time. Enrichment factors (EFs) were found in the range of 20⁻333 folds. The limits of detection of the studied neonicotinoids were in the range of 0.0003⁻0.002 µg mL−1 which are below the maximum residue limits (MRLs) established by the European Union (EU). Good repeatability was obtained with relative standard deviations lower than 1.92% and 4.54% for retention time (tR) and peak area, respectively. The developed extraction method was successfully applied for the analysis of water samples. No detectable residues of neonicotinoids in the studied samples were found.