Simple, rapid, and sensitive determination of beta-blockers in environmental water using dispersive liquid-liquid microextraction followed by liquid chromatography with fluorescence detection

A novel method, dispersive liquid-liquid microextraction combined with liquid chromatography-fluorescence detection is proposed for the determination of three beta-blockers (metoprolol, bisoprolol, and betaxolol) in ground water, river water, and bottled mineral water. Some important parameters, such as the kind and volume of extraction and dispersive solvents, extraction time, pH, and salt effect were investigated and optimized. In the method, a suitable mixture of extraction solvent (60 μL carbon tetrachloride) and dispersive solvent (1 mL acetonitrile) were injected into the aqueous samples (5.00 mL) and the cloudy solution was observed. After centrifugation, the enriched analytes in the bottom CCl(4) phase were determined by liquid chromatography with fluorescence detection. Under the optimum conditions, the enrichment factors (EFs) for metoprolol, bisoprolol, and betaxolol were 180, 190, and 182, and the limits of detection (LODs) were 1.8, 1.4, and 1.0 ng L(-1) , respectively. A good linear relationship between the peak area and the concentration of analytes was obtained in the range of 3-150 ng L(-1) . The relative standard deviations (RSDs) for the extraction of 10 ng L(-1) of beta-blockers were in the range of 4.6-5.7% (n = 5). Compared with other methods, dispersive liquid-liquid microextraction is a very simple, rapid, sensitive (low limit of detection), and economical (only 1.06 mL volume of organic solvent) method, which is in compliance with the requirements of green analytical methodologies.     

悬浮固化分散液液微萃取-高效液相色谱法测定水体中邻苯二甲酸酯

建立了悬浮固化分散液液微萃取（SFO-DLLME）结合高效液相色谱（HPLC）快速测定水样中6种邻苯二甲酸酯（PAEs）的分析方法。通过对影响萃取效率因素的优化,确定了最佳萃取条件：十二烷醇萃取剂20 μL、萃取温度60℃、离子强度20 g/L、萃取时间1 min。6种PAEs在2~2000 μg/L范围内呈良好的线性关系,相关系数（r）为0.9995~0.9999,检出限（S/N=3）为0.3~0.6 μg/L。对自来水、湖水、江水、污水、海水、市售塑料瓶装纯净水和矿泉水进行测定,能检测到部分PAEs。对加标水样进行回收率试验（10、100和1000 μg/L）,6种PAEs的回收率为84.9%~94.5%,相对标准偏差为4.1%~6.8%（n=5）。该法环保、简单,可用于实际水样中6种PAEs的检测分析。     

Determination of triazine herbicides in environmental samples by dispersive liquid-liquid microextraction coupled with high performance liquid chromatography

A simple, rapid, efficient, and environmentally friendly method for the determination of five triazine herbicides in water and soil samples was developed by using dispersive liquid-liquid microextraction (DLLME), coupled with high performance liquid chromatography-diode array detection (HPLC-DAD). The water samples were directly used for DLLME extraction. For soil samples, the target analytes were first extracted by water-methanol (99:1, v/v). In the DLLME extraction method, chloroform was used as an extraction solvent, and acetonitrile as a dispersive solvent. Under the optimum conditions, the enrichment factors of DLLME were in the range between 183-221. The linearity of the method was obtained in the range of 0.5-200 ng/mL for the water sample analysis, and 1-200 ng/g for the soil samples, respectively. The correlation coefficients ranged from 0.9968 to 0.9999. The limits of detection were 0.05-0.1 ng/mL for the water samples, and 0.1-0.2 ng/g for the soil samples. The proposed method has been successfully applied to the analysis of target triazine herbicides (simazin, atrazine, prometon, ametryn, and prometryn) in water and soil samples with satisfactory results.     

Simple determination of some antidementia drugs in wastewater and human plasma samples by tandem dispersive liquid–liquid microextraction followed by high‐performance liquid chromatography

In this work, a simple method, namely, tandem dispersive liquid–liquid microextraction, with a high sample clean‐up is applied for the rapid determination of the antidementia drugs rivastigmine and donepezil in wastewater and human plasma samples. This method, which is based on two consecutive dispersive microextractions, is performed in 7 min. In the method, using a fast back‐extraction step, the applicability of the dispersive microextraction methods in complicated matrixes is conveniently improved. This step can be performed in less than 2 min, and very simple tools are required for this purpose. To achieve the best extraction efficiency, optimization of the variables affecting the method was carried out. Under the optimized experimental conditions, the relative standard deviations for the method were in the range of 6.9–8.7%. The calibration curves were obtained in the range of 2–1100 ng/mL with good correlation coefficients, higher than 0.995, and the limits of detection ranged between 0.5 and 1.0 ng/mL.     

Novel method for the determination of five carbamate pesticides in water samples by dispersive liquid-liquid microextraction combined with high performance liquid chromatography

A novel method for the determination of five carbamate pesticides(metolcarb,carbofuran,carbaryl,isoprocard and diethofencard)in water samples was developed by dispersive liquid-liquid microextraction(DLLME)coupled with high performance liquid chromatography-diode array detector(HPLC-DAD).Some experimental parameters that influence the extraction efficiency were studied and optimized to obtain the best extraction results.Under the optimum conditions for the method,the calibration curve was linear in the c...     

分散液-液微萃取-气相色谱法快速检测番茄中3种拟除虫菊酯类农药

建立了快速(quick)、简单(easy)、便宜(cheap)、有效(effective)、可靠(rugged)和安全(safe)(QuEChERS)的分散液-液微萃取(DLLME)-气相色谱快速测定番茄中拟除虫菊酯类农药残留的方法。样品经乙腈提取,N-丙基乙二胺(PSA)净化,采用DLLME富集,用气相色谱法分析。考察了联苯菊酯、甲氰菊酯和氟氰菊酯在番茄中的残留测定,同时考察了萃取剂种类与体积、分散剂体积以及萃取时间等因素对萃取效率的影响,以40 μL氯仿为萃取剂,1000 μL乙腈为分散剂,萃取时间为60 s。结果表明: 3种拟除虫菊酯类农药在番茄中的检出限分别为0.5、0.5、0.3 μg/kg。在1、10和50 μg/kg添加水平下,联苯菊酯、甲氰菊酯和氟氰菊酯在番茄中的平均回收率分别为89%～109%、92.5%～105%和90%～108%,相对标准偏差分别为2.5%～7.6%、2.8%～5.7%、3.8%～9.1%。该方法简便、快速、安全、价格低廉,重现性好,可用于番茄中拟除虫菊酯类农药的快速检测。     

Supramolecular-based solvent microextraction of carbaryl in water samples followed by high performance liquid chromatography determination

In this study, a simple, rapid, low cost, sensitive and environmentally friendly technique, supramolecular solvent microextraction (SM-SME) followed by high performance liquid chromatography-ultraviolet has been proposed to extract carbaryl from water samples. Parameters, affecting the SM-SME performance such as the weight of decanoic acid (DeA), volume of tetrahydrofuran (THF), pH and salt concentration, were studied and optimised. The effect of the pH on the extraction efficiency was evaluated by one–factor-at-a-time methodology, but the other variables were optimised by a face-centred cube central composite design methodology. Optimum extraction conditions were obtained: DeA: 70 mg; THF: 650 µL; salt concentration: 10% (w/v) NaCl and pH = 2–4), and the performance of the proposed method was evaluated. Under the optimum conditions, good linearity (1.0–500 µg L^?1, r² = 0.9994) was obtained. Limit of detection and limit of quantification were 0.3–1.0 µg L^?1, respectively. Also, the recoveries of the carbaryl were obtained in the ranged from 96% to 105%. Finally, proposed method was successfully applied for the determination of the carbaryl in the water samples of farms run-off and rivers and satisfactory results were obtained.     

凝固漂浮有机液滴-分散液液微萃取结合高效液相色谱法同时测定地表水中多环芳烃和酞酸酯

多环芳烃和酞酸酯是国际公认的优控污染物,因此准确快速地测定水中多环芳烃和酞酸酯非常重要。凝固漂浮有机液滴-分散液液微萃取(DLLME-SFO)是一种简便、快速、环境友好、灵敏度高的样品前处理技术。采用DLLME-SFO同时测定地表水中多环芳烃和酞酸酯的分析方法鲜有报道。该文采用凝固漂浮有机液滴-分散液液微萃取富集技术,结合高效液相色谱紫外/荧光法,建立了同时测定地表水中16种多环芳烃和6种酞酸酯的分析方法。考察优化了影响萃取效率的主要因素,包括萃取剂的种类和用量、分散剂的种类和用量、萃取时间和离子强度等。优化后的萃取实验条件为:5.0 mL水样,10μL十二醇为萃取溶剂,500μL甲醇为分散溶剂,涡旋振荡时间2 min,氯化钠用量0.2 g。目标化合物经多环芳烃专用色谱柱(SUPELCOSIL^TM LC-PAH, 150 mm×4.6 mm, 5μm)结合乙腈-水梯度洗脱分离,16种多环芳烃除苊烯外采用荧光检测,苊烯和6种酞酸酯采用紫外检测,外标法定量。结果表明,22种目标化合物的基质加标回收率为60.2%～113.5%,相对标准偏差为1.9%～14.3%;多环芳...     

Isolation, preconcentration and determination of rhamnolipids in aqueous samples by dispersive liquid-liquid microextraction and liquid chromatography with tandem mass spectrometry

An analytical method based on liquid chromatography-tandem mass spectrometry (LC-MS-MS) was developed for the determination of rhamnolipids. A dispersive liquid-liquid microextraction (DLLME) procedure was used to isolate and concentrate target compounds from aqueous samples collected from surface water, sewage treatment plant effluent and cultivation of microbial culture. Development of the DLLME procedure included optimization of several important parameters such as kind and volume of extracting and dispersing solvents as well as sample pH. Under optimized conditions a two-step extraction with sonication was used. Chloroform was applied as the extracting and acetone as the dispersing solvent. The recoveries of the analytes were 70-87%. Matrix effects investigated for the analytes revealed existence of ionization enhancement for both mono- and dirhamnolipids.     

Temperature-assisted ionic liquid dispersive liquid-liquid microextraction combined with high performance liquid chromatography for the determination of anthraquinones in Radix et Rhizoma Rhei samples

In this article, a novel method termed as temperature-assisted ionic liquid dispersive liquid-liquid microextraction (TA IL-DLLME) combining high performance liquid chromatography with diode array detection (HPLC-DAD) was developed for the determination of anthraquinones in Radix et Rhizoma Rhei samples. The ionic liquid (1-hexyl-3-methylimidazolium hexafluorophosphate) was used to replace volatile organic solvent as an extraction solvent for the extraction of anthraquinones (aloe-emodin, rhein, emodin, chrysophanol and physcion) from Radix et Rhizoma Rhei. Several important parameters influencing the extraction efficiency of TA IL-DLLME such as the type and volume of extraction solvent and disperser solvent, sample pH, extraction time, extraction temperature, centrifugation time as well as salting-out effects were optimized. Under the optimal conditions, the spiked recovery for each analyte was in the range of 95.2-108.5%. The precisions of the proposed method were varied from 1.1% to 4.4% (RSD). All the analytes exhibited good linearity with correlation coefficients (r²) ranging from 0.9986 to 0.9996. The limits of detection for all target analytes were ranged from 0.50 to 2.02 μg L⁻¹ (S/N = 3). The experimental results indicated that the proposed method was successfully applied to the analysis of anthraquinones in Radix et Rhizoma Rhei.     

Comprehensive evaluation of solvent in dispersive liquid-liquid microextraction for determination of itraconazole and hydroxy itraconazole by high performance liquid chromatography with fluorescence detection

This paper aims to propose a multicriteria decision analysis (MCDA) method to evaluate and select solvent in a dispersive liquid-liquid microextraction (DLLME) approach. The DLLME is applied to the determination of itraconazole and hydroxy itraconazole in plasma by high performance liquid chromatography with fluorescence detection (HPLC-FLD). To achieve this goal, extraction efficiency, chromatographic resolution, and greenness of solvent were identified as the three indicators in MCDA. Then, Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) was employed to evaluate and select the solvent. Weight assignment was set up by integrating the subjective scoring from experienced analysts and the objective approach using Shannon’s entropy weight method. Under chosen parameters (extraction solvent: 1-decanol 40 μL, dispersing solvent: methanol 400 μL), the method was validated satisfactorily and applied successfully to the analysis of itraconazole and hydroxy itraconazole in real human plasma samples. The results show that the comprehensive weighted TOPSIS analysis is a promising tool to choose experimental conditions toward an integrative goal. It can provide analysts with a decision making reference to maintain a balance between the analytical performance and eco-friendliness.     

Using dispersive liquid-liquid microextraction and liquid chromatography for determination of guaifenesin enantiomers in human urine

A simple, rapid, and efficient method, dispersive liquid–liquid microextraction (DLLME) coupled with high‐performance liquid chromatography‐fluorescence detector, has been developed for the determination of guaifenesin (GUA) enantiomers in human urine samples after an oral dose administration of its syrup formulation. Urine samples were collected during the time intervals 0–2, 2–4, and 4–6 h and concentration and ratio of two enantiomers was determined. The ratio of R‐(?) to S‐(+) enantiomer concentrations in urine showed an increase with time, with R/S ratios of 0.66 at 2 h and 2.23 at 6 h. For microextraction process, a mixture of extraction solvent (dichloromethane, 100 μL) and dispersive solvent (THF, 1 mL) was rapidly injected into 5.0 mL diluted urine sample for the formation of cloudy solution and extraction of enantiomers into the fine droplets of CH₂Cl₂. After optimization of HPLC enantioselective conditions, some important parameters, such as the kind and volume of extraction and dispersive solvents, extraction time, temperature, pH, and salt effect were optimized for dispersive liquid–liquid microextraction process. Under the optimum extraction condition, the method yields a linear calibration curve in the concentration range from 10 to 2000 ng/mL for target analytes. LOD was 3.00 ng/mL for both of the enantiomers.     

Determination of insecticides in water using in situ halide exchange reaction-assisted ionic liquid dispersive liquid-liquid microextraction followed by high-performance liquid chromatography

A dispersive liquid-liquid microextraction (DLLME) method using in situ halide exchange reaction to form ionic liquid (IL) extraction phase was developed to determine four insecticides (i.e. methoxyfenozide, tetrachlorvinphos, thiamethoxam, and diafenthiuron) in water samples. The preconcentration procedure, followed by high-performance liquid chromatography and variable wavelength detectors (VWD), enabled the formation of the immiscible IL extraction phase; the insecticides were transferred into the IL phase simultaneously, which enhanced the efficiency and sufficiency, greatly shortening the operation time. The experimental parameters affecting the extraction efficiency including volume of extraction IL, extraction and centrifugation times, volume of the sample solution and exchanging reagent, and addition of organic solvent and salt were investigated and optimized. Under optimized conditions, the extractions yielded recoveries of the target analytes from 82 to 102%. The calibration curves were linear, and the correlation coefficient ranged from 0.9990 to 0.9999 under the concentration levels of 5-200 μg/L. The relative standard deviation (n=6) was 2.9-4.6%. The limits of detection (LODs) for the four insecticides were between 0.98 and 2.54 μg/L.     

Temperature-assisted ionic liquid dispersive liquid-liquid microextraction combined with high performance liquid chromatography for the determination of PCBs and PBDEs in water and urine samples

We report on silver–gold core-shell nanostructures that contain Methylene Blue (MB) at the gold–silver interface. They can be used as reporter molecules in surface-enhanced Raman scattering (SERS) labels. The labels are stable and have strong SERS activity. TEM imaging revealed that these nanoparticles display bright and dark stripe structures. In addition, these labels can act as probes that can be detected and imaged through the specific Raman signatures of the reporters. We show that such SERS probes can identify cellular structures due to enhanced Raman spectra of intrinsic cellular molecules measured in the local optical fields of the core-shell nanostructures. They also provide structural information on the cellular environment as demonstrated for these nanoparticles as new SERS-active and biocompatible substrates for imaging of live cells.

Determination of formaldehyde in beverages using microwave-assisted derivatization and ionic liquid-based dispersive liquid-liquid microextraction followed by high-performance liquid chromatography

A simple method based on simultaneous microwave-assisted derivatization and ionic liquid-based dispersive liquid-liquid microextraction (IL-based DLLME) is proposed for the derivatization, extraction and preconcentration of formaldehyde in beverage samples prior to the determination by high-performance liquid chromatography (HPLC). Formaldehyde was in situ derivatized with 2,4-dinitrophenylhydrazine (DNPH) and simultaneously extracted and preconcentrated by using microwave-assisted derivatization and IL-based DLLME in a single step. Several experimental parameters, including type and volume of extraction solvent, type and volume of disperser, microwave power and irradiation time, volume of DNPH, pH of sample solution, and ionic strength were evaluated. When the microwave power was 120 W, formaldehyde could be derivatized and extracted simultaneously only within 90 s. Under optimal experimental conditions, good linearity was observed in the range of 0.5-50 ng/mL with the correlation coefficient of 0.9965, and the limit of detection was 0.12 ng/mL. The proposed method was applied to the analysis of different beverage samples, and the recoveries of formaldehyde obtained were in the range of 84.9-95.1% with the relative standard deviations lower than 8.4%. The results showed that the proposed method was a rapid, convenient and feasible method for the determination of formaldehyde in beverage samples.     

超声辅助分散液液微萃取-高效液相色谱法测定环境空气中的苯并(a)芘

建立了超声辅助分散液液微萃取样品前处理技术,结合高效液相色谱测定环境空气中苯并(a)芘的方法。样品用丙酮:水(1∶4,v/v)混合溶液提取,用氯苯萃取,超声,离心后沉积相进行HPLC测定。对分散液液微萃取的因素进行了优化,在最优条件下,苯并(a)芘的富集倍数达到400倍,检出限为0.4μg·L-1,线性范围为2~200μg·L-1,线性相关系数为0.9998,平均加标回收率为98.2%~99.2%,相对标准偏差为1.6%~2.3%。本方法具有简单便捷、准确灵敏、萃取率高、有机溶剂消耗少等特点,可满足环境空气中苯并(a)芘的快速测定。     

新型分散液液微萃取-高效液相色谱法检测盐酸利多卡因注射液中2,6-二甲基苯胺杂质

以正辛醇为萃取剂,六氟异丙醇（HFIP）为分散剂、正辛醇的自组装诱导剂和密度调节剂,建立了基于HFIP-正辛醇超分子溶剂（SUPRAS）的新型分散液液微萃取（DLLME）方法;应用该萃取方法和HPLC-UV法检测了盐酸利多卡因注射液中的2,6-二甲基苯胺（2,6-DMA）杂质。HFIP-正辛醇SUPRAS为反向胶束聚集体结构,且位于体系的下层,因此有利于萃取富集极性较大的2,6-DMA,且可简化萃取操作。在最佳萃取条件（0.4%（v/v）正辛醇,5%（v/v） HFIP,涡旋3 s,静置3 min,以3000 r/min离心3 min,样品溶液pH 9）下,2,6-DMA的富集因子约为63。在1~100 μg/L范围内方法的线性关系良好（R=0.9989）,检出限为0.33 μg/L,日内、日间精密度均不高于2.5%,回收率为93.9%~100.8%。新型DLLME方法简便、快速、高效、环保,其与HPLC-UV法结合可定量检测盐酸利多卡因注射液中的2,6-DMA。     

Emulsification liquid phase microextraction followed by on-line phase separation coupled to high performance liquid chromatography

An emulsification liquid phase microextraction followed by on-line phase separation coupled to high performance liquid chromatography (HPLC) is introduced based on a novel idea for the separation of dispersed organic phase from aqueous phase. In this method, the dispersed organic extraction phase was filtered using an in-line filter and it was separated from the water sample. The new approach is simple and, in addition to improving some limitations of the conventional emulsification liquid phase microextraction, eliminates the need for centrifugation in the phase separation step.     

漂浮液滴固化分散液液微萃取与高效液相色谱联用检测环境水样中的3种烷基苯酚

建立了漂浮液滴固化分散液液微萃取(DLLME-SFO)方法,以脂肪酸作为萃取剂,以甲醇作为分散剂,与高效液相色谱联用检测了环境水样中3种烷基苯酚。对影响前处理方法的因素进行了详细考察,在最佳萃取条件(60μL萃取剂辛酸、600μL分散剂甲醇、pH值为2.0~8.0、10 mL水样中加入0.5 g NaCl)下,3种烷基苯酚在20~1 500μg/L范围内具有良好的线性关系,相关系数不小于0.998 5,3种目标化合物的检出限为0.45~0.61μg/L,富集倍数为145~169,实际样品中3个水平的加标回收率为80.1%~109.9%。该方法将脂肪酸作为萃取剂,与HPLC联用实现了烷基苯酚的富集与检测,为环境水样中烷基苯酚的检测提供了对环境友好的前处理新方法。     

Quantitation of antioxidants in water samples using ionic liquid dispersive liquid-liquid microextraction followed by high-performance liquid chromatography-ultraviolet detection

A simple and efficient method, ionic liquid-based dispersive liquid-liquid microextraction combined with high-performance liquid chromatography-ultraviolet detection (HPLC-UV), has been applied for the extraction and determination of some antioxidants (Irganox 1010, Irganox 1076 and Irgafos 168) in water samples. The microextraction efficiency factors were investigated and optimized: 1-hexyl-3-methylimidazolium hexafluorophosphate [C(6)MIM][PF(6)] (0.06 g) as extracting solvent, methanol (0.5 mL) as disperser solvent without salt addition. Under the selected conditions, enrichment factors up to 48-fold, limits of detection (LODs) of 5.0-10.0 ng/mL and dynamic linear ranges of 25-1500 ng/mL were obtained. A reasonable repeatability (RSD≤11.8%, n=5) with satisfactory linearity (r(2)≥0.9954) of the results illustrated a good performance of the presented method. The accuracy of the method was tested by the relative recovery experiments on spiked samples, with results ranging from 85 to 118%. Finally, the method was successfully applied for determination of the analytes in several real water samples.