Narrow-bore Tube Research Articles

Preconcentration of Cinnamic Acid Derivatives in Traditional Chinese Medicines by an Effective Dispersive Liquid-Liquid Microextraction Based on a Hydrophobic Deep Eutectic Solvent.

A dispersive liquid-liquid microextraction based on hydrophobic deep eutectic solvent (hDES) was developed for the extraction and quantification of four cinnamic acid derivatives in traditional Chinese medicines coupled with high-performance liquid chromatography-ultraviolet detection. In this method, a hDES (tetrabutylammonium chloride-hexanoic acid, molar ratio of 1:2) was prepared as the extractant. It only took 15 s to handle multiple samples simultaneously by hand-assisted dispersion. The use of a narrow-bore tube reduced the amount of the hydrophobic extractant with easier recovery. The approach was influenced by several key parameters, including the composition and consumption of the DES, sample phase pH, salt amount, extraction time, and centrifugation time, all of which had been investigated and optimized. Moreover, the formation of the DES was characterized by Fourier-transform infrared spectroscopy and differential scanning calorimetry. Under the optimal conditions, enrichment factors of the target analytes ranged from 135 to 220. Satisfactory linearities (r ≥ 0.9977), detection limits (0.2-0.4ng/mL), precision (<8.5%), and accuracy (recoveries: 90.0%-104.6%) were obtained. The method has been successfully applied to the simultaneous extraction and preconcentration of four cinnamic acid derivatives in Chinese medicinal samples with rapidness, high efficiency, and convenience.

Development of salt-induced homogeneous liquid-liquid extraction using a deep eutectic solvent performed in a narrow-bore tube for the extraction of Zn(II), Cu(II), and Cd(II) ions from honey samples.

In this study, a sample preparation procedure based on salt-induced homogeneous liquid-liquid extraction performed in a narrow-bore tube was used for the preconcentration and extraction of Zn(II), Cu(II), and Cd(II) ions from honey samples. To perform the procedure, a mixture of working solution containing sodium chloride, acetonitrile, and a synthesized deep eutectic solvent (as an extraction solvent) was transferred into a narrow tube filled with solid sodium chloride up to a specific level. As the solution flowed through the tube, tiny droplets of the extraction solvent were formed at the boundary between the solution and salt layer. The droplets moved upwards in the tube and eventually collected as a distinct layer on the top of the solution. The separated phase was removed and dispersed into ionized water. After centrifugation, tiny droplets of the extraction solvent containing the analytes were sedimented at the bottom of the tube. The concentrated analytes were measured using flame atomic absorption spectrophotometry. The linear ranges and extraction recoveries were obtained in the ranges of 1.5-100 μg kg-1 and 89.6-94.8%, respectively. The detection limits ranged from 0.35 to 0.48 μg kg-1. Low relative standard deviations (C = 10 μg L-1, n = 6) of 3.1, 2.8, and 3.4% for Zn(II), Cu(II), and Cd(II), respectively, were obtained. Finally, the optimized method was successfully used in determination of concentration of the selected heavy metal ions in various honey samples.

Preparation of a magnetic sorbent based on Tanacetum extract and its application in the extraction of Cu(II) and Pb(II) ions from milk performed in a narrow-bore tube followed by dispersive liquid–liquid microextraction

In this work, an efficient magnetic sorbent has been prepared using the extract of Tanacetum leaves and used in magnetic dispersive solid phase extraction of Cu(II) and Pb(II) ions from high volume of milk samples performed in a narrow-bore tube. For this purpose, first, the sorbent was prepared by mixing Fe3O4 magnetic nanoparticles and Tanacetum leaves extract. After precipitation of the milk proteins with trichloroacetic acid, the sedimented compounds were removed and the upper solution was filled into the narrow-bore tube. Then after that, the mg-level of the prepared sorbent was added. After doing the extraction procedure, the sorbent particles were removed from the tube in the presence of a magnetic field. The adsorbed analytes were desorbed by methanol and to achieve low detection limits, the eluent obtained from the first step was subjected to dispersive liquid-liquid microextraction. Finally, the enriched analytes were monitored by flame atomic absorption spectrometry. The important parameters affecting the method efficiency such as the sorbent amount, type and volume of elution and extraction solvents, vortex time, pH, and ionic strength were studied. Under optimized conditions, the proposed method showed linear ranges of 0.50–40 and 0.75–40 µg L−1 for Cu(II) and Pb(II) ions, respectively. Limits of detection were obtained 0.16 and 0.22 µg L−1 for Cu(II) and Pb(II), respectively. Enrichment factors of 182.5 and 173.7 and extraction recoveries of 95.8 % and 91.2 % were obtained for Cu(II) and Pb(II), respectively. The relative standard deviations (intra- and inter-day precisions) for 5 and 25 µg L−1 of each cation were between 2.4 % and 4.3 %.

Surfactant-assisted salting-out homogenous liquid–liquid extraction based on deep eutectic solvents using central composite design; application in the extraction of natamycin from fruit juices before its determination by HPLC-UV

In this study, for the first time, surfactant-assisted deep eutectic solvent-based salting-out homogenous liquid-liquid extraction performed in a narrow-bore tube has been introduced as a new sample pretreatment approach and used for the isolation of natamycin from fruit juices. In this method, firstly, tween 80 (as a surfactant) and a water-miscible ternary deep eutectic solvent composed of choline chloride: acetic acid: butanol (as an extractant) were added to the sample solution and a homogenous state was formed. This solution was transferred into a narrow-bore tube and in the following, the homogenous solution was broken by addition of sodium chloride (as a phase separation agent). By this action, the analyte was extracted into the produced tiny droplets of extractant. This phase was quantified by high–performance liquid chromatography-ultraviolet detection. Experimental conditions of the developed extraction procedure were investigated and optimized by means of central composite design with variables including surfactant and extraction solvent volume, pH, and sodium chloride amount. Under optimum conditions, low limits of determination and quantification (0.78 and 2.60 ng mL−1, respectively), acceptable repeatability (relative standard deviations of 4.9 and 7.1% for intra- and inter day precisions at a concentration of 25 ng mL−1), and satisfactory extraction recovery (76%) were obtained using the proposed method. At the end, the suggested method was effectively utilized for the analysis of natamycin in different juice samples.

Development of in-situ synthesis of lighter than water deep eutectic solvents under ultrasonic energy in a narrow tube and application in liquid–phase microextraction

ABSTRACT Evaluation of sonication energy effect on in-situ synthesis of deep eutectic solvent-based liquid phase microextraction process was performed in fresh fruit samples for extraction of five neonicotinoids insecticide including clothianidin, imidacloprid, nitenpyram, acetamiprid, and thiacloprid. A suitable amount of choline chloride was dissolved in sample solution and it was poured into a glass narrow-bore tube. Then, a sodium chloride tablet was taken and a few microlitres of hexanoic acid were penetrated into the tablet and it was released into the tube. The narrow–bore tube was located into an ultrasonic bath at controlled frequency and power. The sodium chloride tablet started to dissolve and hexanoic acid was released into the solution and hydrogen bonding was correlated between the ChCl and hexanoic acid. The formed deep eutectic solvent went up through the sample solution and analytes were extracted into the ChCl: hexanoic acid DES. Validation parameters were calculated and low limits of detection (0.04–0.31 ng mL–1) and quantification (0.13–1.03 ng mL–1), high enrichment factors (1280–1780) and extraction recoveries (64–89%), and acceptable precision (RSD ≤7.2%) were obtained. Lastly, the procedure was done on some fresh fruit samples imidacloprid and acetamiprid were detected on some samples.

Magnetic solid-phase extraction method for extraction of some pesticides in vegetable and fruit juices.

A new version of magnetic solid-phase extraction performed in a narrow-bore tube has been proposed for the extraction and preconcentration of different pesticides from various vegetable and fruit juices followed by gas chromatography. A few milligrams of C8 @SiO2 @Fe3 O4 nanoparticles are added into an aqueous sample solution placed in a narrow-bore tube. The sorbent particles move down through the tube under gravity and are collected at the end of the tube by applying an external magnetic field. The end of the tube is narrower and it is connected to a stopcock. After a predetermined time, the stopcock is opened and the solution is passed through the bed of the sorbent maintained by the magnet. Then the adsorbed analytes are desorbed using an elution solvent. To achieve high enrichment factors, a dispersive liquid-liquid microextraction method is carried out. The nanoparticles were characterized by scanning electron microscopy, X-ray diffraction, and FTIR spectroscopy. Under the optimum extraction conditions, limits of detection and quantification were in the ranges of 0.1-0.3 and 0.3-0.9μg/L, respectively. High enrichment factors (1166-1605) and good extraction recoveries (58-80%) were obtained.

Phthalic acid as complexing agent and co-disperser for analysis of zinc and cadmium at trace levels from high volumes of sample on the base of an effervescence-assisted dispersive liquid-liquid microextraction

A green effervescence-assisted dispersive liquid-liquid microextraction based on phthalic acid as complexing agent and co-disperser performed in a narrow-bore tube has been developed for the extraction and preconcentration of zinc and cadmium from high volume of aqueous sample, followed by flame atomic absorption spectrometry. Initially phthalic acid is added to the aqueous sample to form phthalate-metal complexes. Then the sample is transferred by a syringe into a home-made setup consists of a narrow-bore glass tube with its nozzle-shaped head when its bottom connected to a glass balloon containing sodium bicarbonate and an extraction solvent at μL-level. Immediately a reaction occurs between the sodium bicarbonate and the excess amount of phthalic acid, and the produced CO2 leads to the dispersion of the extractant into the sample as fine droplets which result in extraction of the complexes into the extractant. Under the optimum conditions, the calibration curves were linear in the ranges of 0.50–7.5 and 0.30–7.5 μg L−1 for cadmium and zinc, respectively. The detection limits were 0.21 and 0.14 μg L−1 for cadmium and zinc, respectively. Extraction recoveries were 89% and 100%, and enrichment factors were found to be 117 and 131, for cadmium and zinc, respectively. Finally environmental water and fruit juice samples were successfully analyzed using the developed method.

Development of a green effervescence-assisted dispersive liquid–liquid microextraction method using a home-made tablet disperser for trace analysis of Cd(II) and Pb(II)

ABSTRACTAn analytical approach for the determination of trace amounts of Cd(II) and Pb(II) has been developed using a home-made tablet-based effervescence-assisted dispersive liquid–liquid microextraction (DLLME) method which was performed in a narrow-bore tube, followed by flame atomic absorption spectrometry. In this method, a mixture of tartaric acid, sodium bicarbonate and NaCl was used to make the disperser tablet. Then, microlitre level of an extraction solvent was added in the tablet, and then, it was released into a narrow-bore tube containing sample solution and a complexing agent. An acid–base reaction immediately occurred between tartaric acid and sodium bicarbonate, and the produced CO2 led to the dispersion of the extraction solvent into the solution as tiny droplets and subsequent extraction of the analytes. The method made possible the determination of Cd(II) and Pb(II) in the ranges of 0.1–10 and 1.0–20 µg L−1, respectively. The limits of detection were obtained 0.43 and 0.05 µg L−1 for Pb(II) and Cd(II), respectively. The limits of quantifications were 0.80 and 0.09 µg L−1 for Pb(II) and Cd(II), respectively. Repeatability of the method, which is expressed as relative standard deviation, was obtained 3.1% (n = 6, C = 2 µg L−1) and 1.3% (n = 6, C = 0.2 µg L−1) for Pb(II) and Cd(II), respectively. The accuracy of the developed method was verified by analysing a certified reference material, namely SPS-WW2 Batch 108. Relative recoveries (84–107%, obtained at three fortification levels) confirmed the usefulness of the method for analysis of the analytes in the environmental water samples and fruit juices. The method was shown to be fast, reliable and environmentally friendly with low organic solvent consumption.

Magnetic solid phase extraction using Fe3O4@SiO2@C8 nanoparticles performed in a narrow-bore tube followed by dispersive liquid–liquid microextraction for extraction and preconcentration of nine pesticides

In the present work, a new magnetic solid phase extraction method performed in a narrow-bore tube using synthesized Fe3O4@SiO2@C8 magnetic nanoparticles has been developed.

Extraction and preconcentration of nickel, cadmium, cobalt, and lead cations using dispersive solid phase extraction performed in a narrow-bore tube

A new version of DSPE in a narrow-bore tube followed by HPLC-DAD was proposed for the analysis of Ni2+, Cd2+, Co2+, and Pb2+ cations. 2-Propanol is mixed with C18 sorbent and used for dispersing the sorbent into solution containing the cations oxinate complexes. The sorbent passes through the solution in a short time versus passing the solution from the cartridge which is done in the conventional SPE in a long time. In comparison to SPE, the active surface area is larger because of preventing sorbent clogging. EFs and LODs were obtained in the ranges of 831–1073 and 0.05–0.40μgL−1, respectively.

Application of Dispersive Liquid-Liquid Microextraction in Narrow-Bore Tube for Preconcentration and Spectrophotometric Determination of Cadmium in Aqueous Samples

Application of Dispersive Liquid-Liquid Microextraction in Narrow-Bore Tube for Preconcentration and Spectrophotometric Determination of Cadmium in Aqueous Samples

Flotation-assisted dispersive liquid–liquid microextraction method for preconcentration and determination of trace amounts of cobalt: Orthogonal array design

A simple, rapid, and efficient flotation-assisted dispersive liquid–liquid microextraction method was developed for preconcentration of trace amount of cobalt(II) ions. In this technique, a mixture of toluene and methanol (20: 80, v/v) was injected through the septum in the bottom of a narrow-bore tube containing cobalt solution. Afterwards, the fine droplets of extraction solvent were formed and cobalt (as 1-nitroso-2- naphtol complex) was collected on the surface of solution by aeration. The effect of different variables on the extraction efficiency of cobalt such as pH of solution, ligand concentration and injection volume was investigated using orthogonal array design. At optimum conditions, the calibration curve was linear over the range of 10–1000 μg/L. The detection limit, relative standard deviation and enrichment factor were 3 μg/L, 3.9% (n = 10) and 120, respectively. The developed method was successfully applied to the determination of cobalt in water and drug samples.

Development of a green liquid–liquid microextraction method using a solid disperser performed in a narrow-bore tube for trace analysis of some organophosphorus pesticides in fruit juices

A green analytical approach for the determination of trace amounts of organophosphorus pesticides has been proposed using solid-based disperser liquid–liquid microextraction performed in a narrow-bore tube followed by gas chromatography–flame ionization detection. In this method, a sugar cube and acetone (at μL-level) are used as solid disperser and co-disperser, respectively, to facilitate formation of a cloudy state and accelerate mass transfer of the analytes from aqueous solution into the organic phase. The proposed method made possible the determination of analytes in the range of 2–1.0×104μgL−1 with good linearity (coefficients of determination, ≥0.996) and favorable repeatability (relative standard deviation <5% for both intra-day, n=6, and inter-day, n=4, at a concentration of 50μgL−1 of each analyte). Moreover, detection limits and enrichment factors of the analytes ranged from 0.2 to 1.4μgL−1 and 466 to 616, respectively. Relative recoveries (72–102%, obtained at three fortification levels) confirmed the usefulness of the method for analysis of the analytes in fruit juices. The method was shown to be fast, reliable, and environmentally friendly with low organic solvent consumption compared to conventional dispersive liquid–liquid microextraction.

Application of In-Syringe Dispersive Liquid-Liquid Microextraction and Narrow-Bore Tube Dispersive Liquid-Liquid Microextraction for the Determination of Trace Amounts of BTEX in Water Samples.

Two new simple and effective methods based on dispersive liquid-liquid microextraction (DLLME) procedure, termed "in-syringe DLLME (IS-DLLME)" and "narrow-bore tube DLLME (NB-DLLME)", were developed and applied for rapid and simultaneous separation and preconcentration of trace amounts of benzene, toluene, ethylbenzene and xylene isomers in water samples followed by gas chromatographic analysis. Different parameters influencing the extraction efficiency of both methods such as type and volume of the extraction solvent and the disperser solvent; pH, temperature and volume of sample solution and ionic strength of samples were investigated and optimized. Under optimal condition, the limits of detection ranged from 1.7 to 2.4 µg L(-1) for IS-DLLME and 1.5 to 2.2 µg L(-1) for NB-DLLME. Precision (as relative standard deviation) of the two techniques was between 2.1 and 4.6% for IS-DLLME and between 1.5 and 4.5% for NB-DLLME. The enrichment factors found to be between 20-29 and 31-73 for IS- and NB-DLLME, respectively. The applicability of the proposed methods was investigated by analyzing real water samples.

Anesthetic Management for Laser Excision of Ball-Valving Laryngeal Masses

A 47-year-old obese woman with GERD and COPD presents for CO2-laser excision of bilateral vocal fold masses. She had a history of progressive hoarseness and difficulty in breathing. Nasopharyngeal laryngoscopy revealed large, mobile, bilateral vocal cord polyps that demonstrated dynamic occlusion of the glottis. We describe the airway and anesthetic management of this patient with a topicalized C-MAC video laryngoscopic intubation using a 4.5 mm Xomed Laser Shield II endotracheal tube. We examine the challenges of anesthetic management unique to the combined circumstances of a ball-valve lesion and the need for a narrow-bore laser compatible endotracheal tube.

Extraction and Preconcentration of Some Triazole Pesticides in Grape Juice by Salting Out Homogeneous Liquid–Liquid Extraction in a Narrow-Bore Tube Prior to Their Determination by Gas Chromatography–Flame Ionization Detection

A fast and simple extraction and preconcentration method for some triazole pesticides has been developed using a homogeneous liquid–liquid extraction method performed in a narrow-bore tube. The extraction is based on phase separation of a water-miscible organic solvent from aqueous solution in the presence of a salting out agent. In this work, the homogeneous solution of water and acetonitrile (water-soluble extraction solvent) was broken by addition of 30 %, w/v, sodium chloride (salting out agent). After sonication, a small volume of acetonitrile was collected on top of the tube and the extracted analytes in the collected phase were determined by gas chromatography–flame ionization detection. The effect of various experimental parameters including kind and volume of the water-soluble organic solvent, amount of salt, length and diameter of tube, and pH of sample solution was investigated. Under the optimum conditions, calibration graphs were linear over the range of 3–5,000 μg L−1. Relative standard deviations were less than 5.4 % for six repeated determinations (C = 100 μg L−1). Furthermore, the limits of detection (S/N = 3) and quantification (S/N = 10) were obtained in the ranges of 0.60–4.8 and 1.9–16 μg L−1, respectively. This method is very simple and rapid, requiring less than 10 min for sample preparation. It has been successfully utilized for the analysis of triazole pesticides in the grape juice samples.

Salting‐out homogeneous liquid–liquid extraction in narrow‐bore tube: Extraction and preconcentration of phthalate esters from water

In this study a simple and rapid sample preparation technique, homogeneous liquid-liquid extraction based on phase separation in the presence of a salt performed in a narrow-bore tube, followed by GC-flame ionization detection has been developed. In this work, sodium chloride and ACN were used as the salting-out agent and water-soluble extraction solvent, respectively. The homogeneous solution of water and ACN was broken by addition of the salt. Small volume of ACN was collected on top of the tube and the extracted analytes in the collected phase were determined. It has been successfully used for the analysis of five phthalate esters as model compounds in aqueous sample. Experimental parameters affecting the extraction efficiency such as kind and volume of the water-soluble organic solvent, length and diameter of the tube, and pH of the sample solution were investigated. Under the optimal conditions, the LODs were between 0.02 and 0.7 μg/L and enrichment factors were in the range of 172-309. In addition, good linearity (between 1 and 5000 μg/L) and high precision on the base of RSD (<8%, C = 600 μg/L, n = 6) were achieved.

Development of a new dispersive liquid–liquid microextraction method in a narrow-bore tube for preconcentration of triazole pesticides from aqueous samples

In the present work a new, simple, rapid and environmentally friendly dispersive liquid–liquid microextraction (DLLME) method has been developed for extraction/preconcentration of some triazole pesticides in aqueous samples and in grape juice. The extract was analyzed with gas chromatography–flame ionization detection (GC–FID) or gas chromatography–mass spectrometry (GC–MS). The DLLME method was performed in a narrow-bore tube containing aqueous sample. Acetonitrile and a mixture of n-hexanol and n-hexane (75:25, v/v) were used as disperser and extraction solvents, respectively. The effect of several factors that influence performance of the method, including the chemical nature and volume of the disperser and extraction solvents, number of extraction, pH and salt addition, were investigated and optimized. Figures of merit such as linearity ( r 2 > 0.995), enrichment factors (EFs) (263–380), limits of detection (0.3–5 μg L −1) and quantification (0.9–16.7 μg L −1), and relative standard deviations (3.2–5%) of the proposed method were satisfactory for determination of the model analytes. The method was successfully applied for determination of target pesticides in grape juice and good recoveries (74–99%) were achieved for spiked samples. As compared with the conventional DLLME, the proposed DLLME method showed higher EFs and less environmental hazards with no need for centrifuging.

Direct carbonylation of nitrobenzene to phenylisocyanate using gas–liquid slug flow in microchannel

A microreaction system was developed for non-phosgene direct isocyanate synthesis from nitrobenzene and CO gas at pressure (9.5 bar) much lower than those in conventional ones (>100 bar). A gas–liquid slug flow of the reactant mixture was formed in the microchannel for efficient mass transfer across the gas–liquid interfaces. The isocyanate yield of the microflow reaction was shown to be three to six times higher than that of the batch reaction, depending on the inner diameter (i.d.) of the microtube. Higher isocyanate yield was obtained in a narrow-bore tube (0.5 mm i.d.) than in a wide-bore tube (1.0 mm i.d.). The results were interpreted in terms of the length of the liquid slug monitored through transparent PFA tubes. The liquid slug length in the narrow-bore tube (0.6 ± 0.2 mm) was found to be shorter than that in the wide-bore tube (1.1 ± 0.1 mm). This is consistent with the higher isocyanate yield obtained in the narrow-bore tube, because the shorter liquid slug has the larger gas–liquid interfacial area per unit volume.

Development of a new microextraction method based on a dynamic single drop in a narrow-bore tube: Application in extraction and preconcentration of some organic pollutants in well water and grape juice samples

A novel sample preparation technique, the microextraction method based on a dynamic single drop in a narrow-bore tube, coupled with gas chromatography–flame ionization detection (GC–FID) is presented in this paper. The most important features of this method are simplicity and high enrichment factors. In this method, a microdrop of an extraction solvent assisted by an air bubble was repeatedly passed through a narrow-bore closed end tube containing aqueous sample. It has been successfully used for the analysis of some pesticides as model analytes in aqueous samples. Parameters affecting the method's performance such as selection of extraction solvent type and volume, number of extractions, volume of aqueous sample (tube length), and salt effect were studied and optimized. Under the optimal conditions, the enrichment factors (EFs) for triazole pesticides were in the range of 141–214 and the limits of detection (LODs) were between 2 and 112 μg L −1. The relative standard deviations ( C = 1000 μg L −1, n = 6) were obtained in the range of 2.9–4.5%. The recoveries obtained for the spiked well water and grape juice samples were between 71 and 106%. Low cost, relatively short sample preparation time and less solvent consumption are other advantages of the proposed method.