A new concept of hollow fiber liquid-liquid-liquid microextraction compatible with gas chromatography based on two immiscible organic solvents

Arsenic speciation by using emerging sample preparation techniques: a review

Arsenic is a hazardous element that causes environmental pollution. Due to its toxicological effects, it is crucial to quantify and minimize the hazardous impact on the ecology. Despite the significant advances in analytical techniques, sample preparation is still crucial for determining target analytes in complex matrices. Several factors affect the direct analysis, such as trace-level analysis, advanced regulatory requirements, complexity of sample matrices, and incompatible with analytical instrumentation. Along with the development in the sample preparation process, microextraction methods play an essential role in the sample preparation process. Microextraction techniques (METs) are the newest green approach that replaces traditional sample preparation and preconcentration methods. METs have minimized the limitation of conventional sample preparation methods while keeping all their benefits. METs improve extraction efficacy, are fast, automated, use less amount of solvents, and are suitable for the environment. Microextraction techniques with less solvent consumption, such as solid phase microextraction (SPME) solvent-free methods, and liquid phase microextraction (LPME), are widely used in modern analytical procedures. SPME development focuses on synthesizing new sorbents and applying online sample preparation, whereas LPME research investigates the utilization of new solvents.

Deep eutectic solvent as acceptor phase in three-phase hollow fiber liquid-phase microextraction for determination of pyrethroid insecticides from environmental water samples prior to HPLC

In this study, a deep eutectic solvent as acceptor phase was applied in three-phase hollow fiber liquid-phase microextraction (DES-HF-LPME) for the microextraction of two pyrethroids (Permethrin as well as deltamethrin) from environmental water samples prior to HPLC-UV. The deep eutectic solvent was synthesized of tetrabutylammonium bromide/decanoic acid (ratio of 1:2) as an acceptor phase, and 1-decanol was applied as a supported liquid membrane. Some main variables affecting the extraction recoveries, comprising the types/content of extraction solvent and acceptor phase, stirring speed, sample phase pH, and extraction time, were checked out and became optimal. In optimum circumstances, the detection limits and limits of quantitation determined were 0.09-0.12 μgL^-1 and 0.29-0.39 μgL^-1 for deltamethrin and permethrin, respectively. The enrichment factors were 627 and 613, while the relative standard deviations (RSD%, n=5) were calculated to be 4.8% and 5.7%, for deltamethrin and permethrin, respectively. The created technique was satisfyingly assessed to ascertain the two pyrethroid poisons (permethrin and deltamethrin) in environmental water samples.

Trends in hollow fibre liquid phase microextraction for the preconcentration of pharmaceutically active compounds in aqueous solution: A case for polymer inclusion membrane

Low concentrations of pharmaceutically active compounds have been reported in samples from highly complex aqueous environments. Due to their low concentrations, efficient sample pretreatment methods are needed to clean samples and concentrate the compounds of interest prior to instrumental analysis. Hollow fibre liquid-phase microextraction (HF-LPME) is an effective alternative to conventional techniques such as liquid-liquid extraction (LLE) and solid phase extraction (SPE) because it consumes less organic solvent and is less labour intensive with a short extraction time. HF-LPME involves the preconcentration and mass transfer of target analytes from an aqueous sample into an acceptor solution in the lumen of the fibre using a supported liquid membrane (SLM) impregnated in the hollow fibre pores. However, despite the high contaminant selectivity, reproducibility, and enrichment that HF-LPME offers, this technique is limited by membrane instability. Although several advances have been made to address membrane instability, they are either too costly or not feasible for industrial application. Hence, hollow fibre polymer inclusion membrane liquid-phase microextraction (HF-PIM-LPME) was introduced to ameliorate membrane instability. This new approach uses ionic liquids (ILs) as a green solvent, and has demonstrated high membrane stability, good contaminant enrichment, and similar selectivity and reproducibility to HF-SLM-LPME. Hence, this review aims to raise awareness of HF-PIM-LPME as a viable alternative for the selectivity and preconcentration of pharmaceuticals and other contaminants in aquatic environments.

Green Approaches to Sample Preparation Based on Extraction Techniques

Preparing a sample for analysis is a crucial step of many analytical procedures. The goal of sample preparation is to provide a representative, homogenous sample that is free of interferences and compatible with the intended analytical method. Green approaches to sample preparation require that the consumption of hazardous organic solvents and energy be minimized or even eliminated in the analytical process. While no sample preparation is clearly the most environmentally friendly approach, complete elimination of this step is not always practical. In such cases, the extraction techniques which use low amounts of solvents or no solvents are considered ideal alternatives. This paper presents an overview of green extraction procedures and sample preparation methodologies, briefly introduces their theoretical principles, and describes the recent developments in food, pharmaceutical, environmental and bioanalytical chemistry applications.

Novel generation of deep eutectic solvent as an acceptor phase in three-phase hollow fiber liquid phase microextraction for extraction and preconcentration of steroidal hormones from biological fluids

In this study, a novel generation of deep eutectic solvents (DESs) was used as an acceptor phase in three-phase hollow fiber liquid phase microextraction (HF-LPME) based on two immiscible organic phases. It was compared with other common DESs for extraction and preconcentration of dydrogesterone (DYD) and cyproterone acetate (CPA) from urine and plasma samples. The extracted analytes were analyzed by high performance liquid chromatography with UV-vis detector (HPLC-UV). This phosphonium based DES due to low volatility, low price and multifunctionality introduced itself as worthy next generation of acceptor phase in HF-LPME. The factors affected on extraction efficiency of the analytes were investigated and optimized. The performance of the proposed method was studied in terms of linear ranges (LRs from 1 to 500µgL^-1 with R² ≥ 0.9946), precision (RSD% ≤ 6.3) and limits of detection (LODs in the range of 0.5-2µgL^-1). Under the optimized conditions, preconcentration factors in the range of 187-428 were obtained. Finally, the method was applied to the analysis of DYD and CPA in human urine and plasma samples and desirable results were obtained.

Microextraction in urine samples for gas chromatography: a review

Since the complexity origin of biological samples, the research trends have been directed to the development of new miniaturized sample preparation techniques. This review provides a comprehensive survey of past and present microextraction methods followed by GC analysis for preconcentration and determination of various analytes in urine samples. These techniques have been classified in three general groups, including liquid-, solid- and membrane-based techniques. The principal of different microextraction methods that are located in each general group as well as their various extraction modes and the recent developments introduced for them has been presented. Subsequently, a comparison survey has been carried out among different microextraction techniques and finally a future perspective has been predicted based on the existing literature.

Applications of liquid-phase microextraction in the sample preparation of environmental solid samples

Solvent extraction remains one of the fundamental sample preparation techniques in the analysis of environmental solid samples, but organic solvents are toxic and environmentally harmful, therefore one of the possible greening directions is its miniaturization. The present review covers the relevant research from the field of application of microextraction to the sample preparation of environmental solid samples (soil, sediments, sewage sludge, dust etc.) published in the last decade. Several innovative liquid-phase microextraction (LPME) techniques that have emerged recently have also been applied as an aid in sample preparation of these samples: single-drop microextraction (SDME), hollow fiber-liquid phase microextraction (HF-LPME), dispersive liquid-liquid microextraction (DLLME). Besides the common organic solvents, surfactants and ionic liquids are also used. However, these techniques have to be combined with another technique to release the analytes from the solid sample into an aqueous solution. In the present review, the published methods were categorized into three groups: LPME in combination with a conventional solvent extraction; LPME in combination with an environmentally friendly extraction; LPME without previous extraction. The applicability of these approaches to the sample preparation for the determination of pollutants in solid environmental samples is discussed, with emphasis on their strengths, weak points and environmental impact.

Simultaneous derivatization and extraction of nitrophenols in soil and rain samples using modified hollow-fiber liquid-phase microextraction followed by gas chromatography-mass spectrometry

A simple and sensitive method based on a modified hollow-fiber liquid-phase microextraction followed by gas chromatography-mass spectrometry has been successfully developed for the extraction and simultaneous derivatization of some nitrophenols (NPs) in soil and rain samples. Microwave-assisted solvent extraction was used for the extraction of NPs from the soil, while the rain sample was directly applied to the previously mentioned method. Briefly, in this method, the analytes were extracted from aqueous samples into a thin layer of organic solvent (dodecane + 10% tri-n-octylphosphine oxide) sustained in the pores of a porous hollow fiber. Then, they were back-extracted using a small volume of organic acceptor solution (25 μl; 10 mg/L N-methyl-N-(trimethylsilyl)trifluoroacetamide, as derivatization reagent, in acetonitrile) that was located inside the lumen of the hollow fiber. Under the optimized extraction conditions, enrichment factors of 255 to 280 and limits of detection of 0.1 to 0.2 μg/L (S/N = 3) with dynamic linear ranges of 1-100 μg/L were obtained for the analytes. The accuracy of the approach was tested by the relative recovery experiments on spiked samples, with results ranging from 93 to 113%. The method was shown to be rapid, cost-effective, and potentially interesting for screening purposes.

Effects of push/pull perfusion and ultrasonication on the extraction efficiencies of phthalate esters in sports drink samples using on-line hollow-fiber liquid-phase microextraction

In previous studies, we developed a process, on-line ultrasound-assisted push/pull perfusion hollow-fiber liquid-phase microextraction (UA-PPP-HF-LPME), combining the techniques of push/pull perfusion (PPP) and ultrasonication with hollow-fiber liquid-phase microextraction (HF-LPME), to achieve rapid extraction of acidic phenols from water samples. In this present study, we further evaluated three more-advanced and novel effects of PPP and ultrasonication on the extraction efficiencies of neutral high-molecular-weight phthalate esters (HPAEs) in sports drinks. First, we found that inner-fiber fluid leakage occurs only in push-only perfusion-based and pull-only perfusion-based HF-LPME, but not in the PPP mode. Second, we identified a significant negative interaction between ultrasonication and temperature. Third, we found that the extraction time of the newly proposed system could be shortened by more than 93%. From an investigation of the factors affecting UA-PPP-HF-LPME, we established optimal extraction conditions and achieved acceptable on-line enrichment factors of 92-146 for HPAEs with a sampling time of just 2 min.

Automated preconcentration and analysis of organic compounds by on-line hollow fiber liquid-phase microextraction-high performance liquid chromatography

The present work describes the first automated instrument, based on on-line hollow fiber liquid-phase microextraction (HF-LPME)-high performance liquid chromatography (HPLC), for the preconcentration and determination of organic compounds in various matrices. Using an automated syringe pump for loading the supported liquid membrane and acceptor solvents, a platform lift for moving the sample vial, a sampling loop for on-line injection of the extract to HPLC, along with an electronic board with an AVR microcontroller for storage of data and instrument programs, a sample preparation-HPLC method was developed that allowed sample extraction and extract injection to be carried out completely automatically. Pyridine and pyridine derivatives were chosen for the development and for testing the applicability of the automated instrument. The limits of detection (3 times the S/N) ranged from 0.5 to 1.0 μgL(-1). Effective preconcentration of the analytes was also achieved (preconcentration factors of between 40 and 220). The main advantages of the method developed are minimum sample manipulation, full automation, suitable extraction time, low solvent consumption, and ease of use. The applicability of the on-line automated HF-LPME/HPLC-UV instrument was validated for quantitative extraction and determination of pyridines in cigarette smoke.

Three-phase hollow fiber liquid-phase microextraction based on two immiscible organic solvents for determination of tramadol in urine and plasma samples

Recently, the new concept of three-phase liquid microextraction was introduced based on applying two immiscible organic solvents in lumen and wall pores of hollow fiber. In the present work, this novel microextraction technique combined with gas chromatography-mass spectrometry has been developed for determination of tramadol, an analgesic agent, in plasma and urine samples. A systematic investigation of the proposed method was applied to find optimal extraction conditions and evaluate the interaction effects between the factors by designing experiments according to the methodology of Box-Behnken response surface design. Analysis of variance (ANOVA) revealed that the important factors contributing to extraction efficiency are extraction time, stirring rate and hollow fiber length. Under the optimum conditions, the developed method provided a preconcentration factor of 546, good repeatability (RSD %=6.4), and good linearity (r(2)=0.995) for spiked plasma and urine real samples. The linear dynamic range from 0.1 to 400 μg L(-1) and limit of detection (LOD) of 0.08 μg L(-1) were obtained under selected ion monitoring mode. The results demonstrated that three-phase hollow fiber microextraction based on two immiscible solvents is a simple and accurate technique with very good preconcentration factor and clean-up for extraction of tramadol from biological samples.